Catalytic degradation of peroxide-based explosives

Abstract

There is a significant gap in capability of EOD personnel to deal with organic peroxide explosives where convention EOD techniques such as "blow in place" are unavailable. With a growing threat of terrorism around the world, a method of destruction of organic peroxide explosives such as TATP that provides a safe, rapid, and logistically simple option for EOD personnel is required. The present invention relates to a method and associated kit of parts for the non-explosive chemical degradation of one or more organic peroxides, the method comprising treating the one or more organic peroxides with one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids.

Description

CATALYTIC DEGRADATION OF PEROXIDE-BASED EXPLOSIVESRelated Application

[0001] The present application claims convention priority to Australian Provisional Patent Application No. 2023903650, filed 14 November 2023. The content of AU’650 is incorporated herein in its entirety.Field of the Invention

[0002] The present invention relates to the safe degradation of peroxide -based explosives that are often prepared for nefarious use.

[0003] In particular, the invention relates to a method for the non-explosive chemical degradation of one or more organic peroxides, the method comprising treating the one or more organic peroxides with one or more Lewis acids and one or more aldehyde-containing solvents.

[0004] Although the present invention will be described hereinafter with reference to its preferred embodiment, it will be appreciated by those of skill in the art that the invention may be embodied in many other forms.Background of the Invention

[0005] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0006] An explosive is a substance which can sustain a rapid chemical reaction in which the initial material is converted into a large amount of gas and heat in a short space of time. This rapid reaction is propagated through the material with a shock wave. For something to explode, this shock wave must be initiated through detonation. Most explosives available, especially to a potential terrorist, on a destructive scale are not sensitive enough to be reliably detonated in isolation. For detonation, they require a highly sensitive explosive to translate a shock wave into the bulk of material, called a primary explosive. The acquisition of these primary explosives is a key aspect of terrorist bombing operations.

[0007] Peroxide-based explosives are often prepared for nefarious use. Some of the better- known examples include Jakarta, in May 2018, where motorcycles delivered peroxide-based bombs to a Catholic church, and Manchester, in May 2017, in which a local stadium was targeted by a suicide -bomber using a peroxide -based explosive inside a pressure cooker. Closerto home, in Perth, in July 2013, 3 kilograms of white powder was discovered in a bag in fishing estuary area. Thinking the materials were drugs, Police threw them into the back of squad cars and took them to the station for further testing. Luckily, none of the bags detonated as they were later confirmed to contain a highly explosive organic peroxide.

[0008] Such peroxide -based explosives include any cyclic or acyclic peroxides. Nonlimiting examples include triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD), methylethylketone peroxide (MEKP) and similar. These monomolecular explosives share the characteristics of extreme sensitivity to heat and shock, with TATP and HMTD also having extreme sensitivity to friction (being crystalline powders) and static electricity.

[0009] TATP is extremely dangerous to handle, posing significant hazards for Explosive Ordinance Disposal (EOD). There are several ways in which EOD operators may encounter TATP. It can be encountered as a detonator of another main charge, in which case there are often more immediate concerns for harm mitigation and disposal. However, when found acting as the main charge, the sensitivity of TATP poses a challenge to conventional EOD methods and equipment. This risk is also regularly encountered when improvised laboratories with bulk TATP in production are found - in fact the unknown state of the explosive in these situations can be more problematic.

[0010] The safest method of dealing with any explosive disposal is to detonate the charge, called “blow- in-place”. This is typically done using a counter charge or by remotely triggering the device that has been found. However, there are many situations where blow-in-place procedures are not viable including potential damage to critical infrastructure - a common terrorist target. In these situations, render safe procedures differ depending on the country or even particular organisations. One common technique is to dissolve the bulk organic explosive in a solvent such as diesel fuel. This method poses several significant risks and has not been subject to rigorous testing. It is unknown if the dissolution process is exothermic, posing the risk that sufficient localised heat of dissolution may cause detonation or fire. Another risk that this process poses is that during the transportation of this bulk solvent, some TATP may crystallise and be available for detonation. In theory, this could act as a primary charge for the bulk explosive- solvent mixture, creating a more significant explosive threat.

[0011] To solve this problem, a means of destruction of TATP is required that provides more flexibility in dealing with situations where blow-in-place render safe procedures are unsuitable. For this to be effective, the procedure needs to be relatively safe, rapid, and logistically simple, i.e., not requiring large volumes of solvent or hazardous materials.

[0012] Law enforcement and military organisations around the world face great risk whendealing with these explosives due to their sensitivity and instability. With the ability to reduce or remove these risks comes an increase to public safety and a lower threat to first responders. Currently, there are no products on the market that can safely degrade peroxide explosives chemically. The current best practice is to either blow the material up, destroy it by fire, or to desensitise it with a surfactant (e.g., soapy water, WD40) before moving to safe disposal area. Often, these methods are not suitable for the location or surrounding environment.

[0013] US 3,076,852, to Wacker-Chemie GmbH and entitled “Process for manufacturing organic peroxide compounds” describes a process for the manufacture of a peroxide compound selected from cyclohexanone, benzaldehyde, acetone, and methylethyl ketone, which comprises reacting the compound with an organic peracid selected from peracetic acid and perpropionic acid in the presence of a condensing agent such as sulfuric acid, perchloric acid, and pyridine. However, this document teaches only preparation of organic peroxides and not their degradation.

[0014] US 4,057,442, to Thiokol Corporation, and entitled “Method of disposal of pyrotechnic compositions”, describes a method for the safe, relatively pollution free disposal of pyrotechnic compositions. High percentage recoveries of the inorganic oxidizer and metallic fuel are achieved, resulting in significant cost benefits, while using a minimum of energy. Lewis acids (and Lewis bases) are used as depolymerisation agents to disrupt the matrix structure of the pyrotechnic composition. However, the document discloses little other than the general concept of a Lewis acid being used as a degradation agent.

[0015] US 4,758,387, to the United States Government, and entitled “Disposal of solid propellants”, teaches a method for the disposal of solid propellants comprising the steps of placing solid propellant and a solution of water and detergent in a closed container with the solution covering the solid propellant; adding compressed air in superheated steam into the solution so that the solution and solid propellant are under up to 10 atmospheres, and so that the temperature of the solution is raised sufficiently to break down the solid propellant into constituents and thereby create a water slurry; and removing of the constituents. The document describes a physical rather than a chemical degradation and the solid propellants are not organic peroxides.

[0016] US 4,231,822, also to the United States Government, and entitled “Non-polluting process for desensitising explosives”, teaches a method for desensitizing an explosive organic material comprising preparing a slurry of the explosive material in an aqueous solution of a reductant containing no elements besides those contained in the explosive material, the reductant being selected from acetaldehyde, citric acid, formaldehyde, formic acid, lactic acid, maleic acid, malic acid, malonic acid, oxalic acid, tartaric acid and glucose, wherein the explosive material ispresent essentially in solid, particulate form, and reacting the explosive material and the reductant in the slurry for a period of time sufficient to achieve desensitisation of the explosive material. The method described is particular to organic explosives such as TNT, RDX, nitroglycerine, nitroguanidine and nitrocellulose. However, there is no teaching or suggestion that the method is applicable to organic peroxides.

[0017] US 2015 / 004710, to Massachusetts Institute of Technology, and entitled “Reagents for oxidiser-based chemical detection”, describes reagents and methods for detection of oxidisers and inorganic salts and other analytes. The reagents can interact with their target analytes, especially oxidiser compositions or oxidiser-based explosives, to selectively enhance their ionisation yield, interacting by chemical reaction or by forming an associative adduct which facilitates their detection. Paragraph

[0011] mentions TATP, DADP and HMTD. However, the disclosure is directed to a method of detecting such compounds rather than a method of remediating them.

[0018] Bali [Bali, M.; Novel Strategies for the safe degradation of organic peroxide explosives: A mechanistic investigation. PhD Dissertation, University of New South Wales, 2014] investigated Lewis acids as a novel class of catalyst for triacetone triperoxide (TATP) degradation. TiCL was found to be highly effective, with degradation resulting in a mix of ester and ketone products. For this reason, it was proposed that the mechanism involved a Baeyer- Villiger (BV) rearrangement. At higher ratios, TiCL lead to a high rate of decomposition, however a dramatic reduction in reaction rate at lower ratios was observed. The author suggested that TiCL is rapidly converted to a different and less active Ti species (TiA). TiA was the result of product-binding which reduced its oxophilicity and prevented it from promoting the characteristic BV methyl migration, leading to an alternate pathway. The BV rearrangement which results in an ester is significant as it interrupts the equilibrium between TATP and DADP. The denial of an equilibrium is a significant advantage of this mechanism, as given the wrong environmental conditions, explosive products will be reformed. However, TiCL requires strict anhydrous conditions and its tendency to hydrolyse was found to be a barrier to its use in the field, confining its use to the laboratory.

[0019] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0020] A relatively safe method of chemically degrading organic peroxide compounds may reduce or remove the risk to first responders and increase public safety. Such a method or product could be allocated to numerous locations within law enforcement or military communities, in dozens of countries facing threats from peroxide explosives. Hotspots right nowinclude Indonesia, Thailand, India, Vietnam, Pakistan, Philippines, Malaysia, etc., and across Europe.

[0021] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0022] Although the invention will be described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.Summary of the Invention

[0023] With the goal of finding a catalytic breakdown mechanism of cyclic peroxides such as TATP, previous studies have identified potential pathways of chemical degradation through Baeyer-Villiger-type mechanisms using Lewis acids. Initial work reviewed the applicability of water-tolerant metal triflate Lewis acids identified in previous research as potential catalysts for the degradation of tripentanone triperoxide (TPTP) - a safer analog molecule of TATP. Through degradation experiments monitored by NMR and ABTS assays, it was found that these Lewis acids can catalyse ring opening of TPTP and some slow degradation. With these catalysts, a new method of TPTP degradation was developed utilising the oxidation of aromatic aldehydes. Through NMR, GCMS, and DSC tracked degradation experiments, a unique Dakin oxidationtype mechanism of reaction is proposed, and partially optimised reaction conditions are developed. The reaction is shown to effectively translate to TATP, producing rapid chemical degradation with the potential for field relevant application. By identifying a unique method of degradation of TATP, the present invention provides a foundation for the development of a vitally important capability for EOD personnel in their response to explosive threats.

[0024] According to a first aspect of the present invention there is provided a field-relevant method for the non-explosive chemical degradation of one or more organic peroxides, the method comprising:

[0025] treating the one or more organic peroxides with one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ring-open and thereby degrade the one or more organic peroxides.

[0026] The one or more organic peroxides may be any organic peroxide, but particularly those exhibiting explosive characteristic and even more particularly those prepared synthetically for nefarious use.

[0027] In an embodiment, the one or more organic peroxides are selected from any cyclic or acyclic peroxides. Preferably, the one or more organic peroxides are selected from tripentanone triperoxide (TPTP), triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0028] In an embodiment, the one or more organic peroxides are selected from triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0029] In an embodiment, the one or more organic peroxides comprise triacetonetriperoxide (TATP).

[0030] The one or more aromatic aldehydes may comprise any aromatic aldehydes, pure or crude, a single aromatic aldehyde or a mixture of more than one aromatic aldehyde.

[0031] In an embodiment, the one or more aromatic aldehydes comprise benzaldehyde.

[0032] In an embodiment, the one or more aromatic aldehydes are selected from benzaldehydes substituted at the ortho- and / or para-positions by one or more electron-donating functional groups.

[0033] In an embodiment, the one or more electron-donating functional groups is methoxy.

[0034] In an embodiment, the one or more aromatic aldehydes are selected from o- anisaldehyde and p-anisaldehyde.

[0035] In an embodiment, the one or more aromatic aldehydes comprise p-anisaldehyde.

[0036] The one or more Lewis acids may comprise any Lewis acids, but more particularly, water-tolerant Lewis acids or those exhibiting low sensitivity to moisture, given the practical requirement that the inventive method is field-relevant, which will often require the Lewis acids to work in the presence of water.

[0037] In an embodiment, the one or more Lewis acids are selected from metal triflates.

[0038] In an embodiment, the metal triflates are selected from Y(OTf)3, Bi(OTf)3, In(OTf)3,Sc(OTf)3, or triflates of other transition metals such as iron, copper, etc.

[0039] In an embodiment, the metal triflates are selected from Bi(OTf)3, In(OTf)3, and Sc(OTf)3.

[0040] In an embodiment, the metal triflates comprise Bi(OTf)3.

[0041] The organic peroxide and the catalyst (z.e., the one or more metal triflates) may be present in any applicable weight ratio. A moderate catalytic ratio is about 5: 1, however, the inventive method has been shown to have efficacy at other weight ratios.

[0042] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 50: 1 and about 1: 1.

[0043] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 30: 1 and about 2:1.

[0044] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 20: 1 and about 3: 1.

[0045] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 10: 1 and about 4: 1.

[0046] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of about 5: 1.

[0047] The aromatic aldehyde is provided in molar excess with respect to both the one or more organic peroxides and the one or more metal triflates.

[0048] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:50 and about 1:5.

[0049] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:25 and about 1:5.

[0050] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1: 15 and about 1:5.

[0051] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of about 1: 10.

[0052] In an especially preferred embodiment, the one or more aromatic aldehydes comprises p-anisaldehyde, and the one or more Lewis acids comprises Bi(OTf)s. Preferably, the p-anisaldehyde, and the Bi(OTf)3 are present in a weight ratio of about 250:1.

[0053] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 10 min to about 10 h.

[0054] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 30 min to about 4 h.

[0055] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 1 h.

[0056] In an embodiment, the method is performed under ambient conditions.

[0057] In an embodiment, the one or more aromatic aldehydes and the one or more Lewis acids are combined prior to treating the one or more organic peroxides.

[0058] In an embodiment, the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides sequentially.

[0059] In an embodiment, the sequential addition of the one or more aromatic aldehydes and the one or more Lewis acids to the one or more organic peroxides is performed with the one ormore aromatic aldehydes added first.

[0060] In an embodiment, the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides by spraying, misting, deluging, or dropwise.

[0061] In an embodiment, the method further comprises an initial step of determining the presence of the one or more organic peroxides. This may be performed by conventional means, for example, through use of ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), or by remote instrumental methods such as Raman spectroscopy.

[0062] In an embodiment, the method further comprises the step of determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation. Such a step is preferably given that the catalyst may be moisture- sensitive above a certain level.

[0063] According to a second aspect of the present invention there is provided the use of one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ring-open and thereby chemically degrade one or more organic peroxides.

[0064] In an embodiment, the one or more organic peroxides are selected from tripentanone triperoxide (TPTP), triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0065] In an embodiment, the one or more organic peroxides are selected from triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0066] In an embodiment, the one or more organic peroxides comprise triacetonetriperoxide (TATP).

[0067] In an embodiment, the one or more aromatic aldehydes comprise benzaldehyde.

[0068] In an embodiment, the one or more aromatic aldehydes are selected from benzaldehydes substituted at the ortho- and / or para-positions by one or more electron-donating functional groups.

[0069] In an embodiment, the one or more electron-donating functional groups is methoxy.

[0070] In an embodiment, the one or more aromatic aldehydes are selected from o- anisaldehyde and p-anisaldehyde.

[0071] In an embodiment, the one or more aromatic aldehydes comprise p-anisaldehyde.

[0072] In an embodiment, the one or more Lewis acids are selected from metal triflates.

[0073] In an embodiment, the metal triflates are selected from post-transition metal or pnictogen metal triflates.

[0074] In an embodiment, the metal triflates are selected from Y(OTf)3, Bi(OTf)3, In(OTf)3,and Sc(OTf)3.

[0075] In an embodiment, the metal tritiates are selected from Bi(0Tf)3, In(OTf)s, andSc(OTf)3.

[0076] In an embodiment, the metal tritiates comprise BiiOTfj -

[0077] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 50: 1 and about 1: 1.

[0078] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 30: 1 and about 2: 1.

[0079] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 20: 1 and about 3: 1.

[0080] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of between about 10: 1 and about 4: 1.

[0081] In an embodiment, the organic peroxide and the catalyst are present in a weight ratio of about 5: 1.

[0082] In an embodiment, the aromatic aldehyde is provided in molar excess.

[0083] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:50 and about 1:5.

[0084] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:25 and about 1:5.

[0085] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1: 15 and about 1:5.

[0086] In an embodiment, the organic peroxide and the aromatic aldehyde are present in a weight ratio of about 1: 10.

[0087] In an especially preferred embodiment, the one or more aromatic aldehydes comprises p-anisaldehyde, and the one or more Lewis acids comprises Bi(OTf)s. Preferably, the p-anisaldehyde, and the Bi(OTf)3 are present in a weight ratio of about 250:1.

[0088] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 10 min to about 10 h.

[0089] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 30 min to about 4 h.

[0090] In an embodiment, the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 1 h.

[0091] In an embodiment, the method is performed under ambient conditions.

[0092] In an embodiment, the one or more aromatic aldehydes and the one or more Lewisacids are combined prior to treating the one or more organic peroxides.

[0093] In an embodiment, the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides sequentially.

[0094] In an embodiment, the sequential addition of the one or more aromatic aldehydes and the one or more Lewis acids to the one or more organic peroxides is performed with the one or more aromatic aldehydes added first.

[0095] In an embodiment, the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides by spraying, misting, deluging, or dropwise.

[0096] According to a third aspect of the present invention there is provided a kit of parts for performing a field-relevant method for the non-explosive chemical degradation of one or more organic peroxides, the kit comprising:

[0097] one or more aromatic aldehydes;

[0098] one or more Lewis acids; and

[0099] instructions for their deployment to ring-open and thereby degrade the one or more organic peroxides. In an embodiment, the kit further comprises a means of detecting or confirming the presence of the one or more organic peroxides. This may be performed by conventional means, for example, through use of ABTS (2,2’-azino-bis(3-ethylbenzothiazoline- 6-sulfonic acid), or by remote instrumental methods such as Raman spectroscopy.

[0100] In an embodiment, the kit further comprises a means of determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation. Such means are preferably given that the catalyst may be moisture- sensitive above a certain level.

[0101] In an embodiment, the one or more aromatic aldehydes and one or more Lewis acids are present in a weight ratio of between about 1:25 and about 1:5.

[0102] In an embodiment, the kit further comprises one or more mixing and / or delivery apparatus for deploying the kit.Definitions

[0103] In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skillin the art to which the invention pertains.

[0104] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0105] As used herein, the phrase “consisting of’ excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of’ (or variations thereof) appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole. As used herein, the phrase “consisting essentially of’ limits the scope of a claim to the specified elements or method steps, plus those that do not materially affect the basis and novel characteristic(s) of the claimed subject matter.

[0106] With respect to the terms “comprising”, “consisting of’, and “consisting essentially of’, where one of these three terms is used herein, the presently disclosed and claimed subject matter may include the use of either of the other two terms. Thus, in some embodiments not otherwise explicitly recited, any instance of “comprising” may be replaced by “consisting of’ or, alternatively, by “consisting essentially of’.

[0107] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term “about”, having regard to normal tolerances in the art. The examples are not intended to limit the scope of the invention. In what follows, or where otherwise indicated, “%” will mean “weight %”, “ratio” will mean “weight ratio” and “parts” will mean “weight parts”.

[0108] The term “substantially” as used herein shall mean comprising more than 50% by weight, where relevant, unless otherwise indicated.

[0109] The term “about” should be construed by the skilled addressee having regard to normal tolerances in the relevant art.

[0110] The recitation of a numerical range using endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0111] The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

[0112] It must also be noted that, as used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0113] The prior art referred to herein is fully incorporated herein by reference unless specifically disclaimed.

[0114] Although example embodiments of the disclosed technology are explained in detail herein, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the disclosed technology be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways.

[0115] This specification is prepared having regard to the principles of general application. As such, where the specification discloses a principle of general application, the claims may be drafted in correspondingly general terms (Biogen v Medeva

[1997] RPC 1 at 48). A “principle of general application” is a general principle that can be practically applied in making a class of products, or in working a process, including where the claims define the products or process(es) in terms of the result to be achieved.

[0116] A feature in the claims stated in general terms will represent a principle of general application, where it is reasonable to expect (reasonable to predict) that the claimed invention will work with anything that falls within the general term. Such a feature defined in general terms may be a major part of the claim, or it may be a simple descriptive word. In either case, a feature in the claims expressed in general terms will be sufficiently enabled if the disclosure enables at least one form of, or one application of, a general principle in respect of the feature, and the person skilled in the art would reasonably expect the invention to work with anything that falls within the general term. (Kirin- Amgen Inc. v Hoechst Marion Roussel Ltd

[2005] RPC 9 at

[0112] ).

[0117] Where the claims are more broadly drafted they may be considered enabled if, prima facie: a) the disclosure teaches a principle that the person skilled in the art would need to follow in order to achieve each and every embodiment falling within a claim; and b) the specification discloses at least one application of the principle and provides sufficient information for the person skilled in the art to perform alternative applications of the principle in a way that, while not explicitly disclosed, would nevertheless be obvious to the person skilled in the art (T 484 / 92).

[0118] As rationalised herein, a principle of general application applies from the testing ofTPTP as a proxy for organic peroxides, per se. It will be understood that the practical difficulties associated with testing highly explosive materials suggest that the present Applicant is entitled to rely upon testing with a substantially less dangerous analog.Brief Description of the Drawings

[0119] A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:

[0120] Figure 1 shows the1H-NMR tracked reaction progression of Bi(OTf)3 catalysed degradation of TPTP. The Bi(OTf)s reaction as progressed over 12 hours at 25 °C with TPTP:Bi(OTf)3 at 10: 1 mol ratio. The major product of the reaction is observed to be 3P (1H- NMR (CDC13) 6 1.06 (t, 4H, CH3), 52.44 (q, 6H, CH3) as shown with “star”.

[0121] Figure 2 is an annotated ’ H-NMR spectrum for catalytic breakdown of TPTP by Bi(OTf)3, In(OTf)3, and Sc(OTf)3 after 2 hours. Labels: “square” is grease contamination, “circle” is water, “EP” is ethyl propanoate, “3P” is 3-pentanone, “DPDP” is dipentanone diperoxide (ring contraction product of TPTP). Open rings likely suggest structures similar to DPPDHP (3,3'-dihydroperoxy-3,3'-dipentyl peroxide; a potential degradation intermediate of TPTP).

[0122] Figure 3 shows a ’ H-NMR tracked progression of the catalytic breakdown of TPTP by Bi(OTf)3 after 64 hours. The relative amount of TPTP present is similar to that shown in Figure 2.

[0123] Figure 4 shows the ABTS assay results of TPTP degradation by Bi(OTf)3 at 30, 60 and 90 min intervals in the absence of an aromatic aldehyde. The growth of hydroperoxides shows relatively linear growth over this time period, supporting the suggestion that the degradation mechanism produces hydroperoxides with the possibility of recyclising into explosive products.

[0124] Figure 5 shows TPTP degradation tracking using ' H-NMR at 20 min and 4 h of Bi(OTf)3, In(OTf)3, and Sc(OTf)3. The graphic shows that all catalysts acted to significantly degrade the TPTP in the 4 h time period. Catalysts were prepared at 1:5 mol ratio catalyst:TPTP. Benzaldehyde was added at an approximate mol ratio of 50:1 benzaldehyde:TPTP. 20 min and 4 h were chosen as an example of the general feasibility of the reaction. Labels: “circle” is TPTP and “square” is 3-pentanone.

[0125] Figure 6 shows the 'H-NMR tracked 24 h degradation of TPTP by Bi(OTf)3 and benzaldehyde (6.9-10.1 ppm). Bi(OTf)3 was prepared at 1:5 mol ratio (catalyst:TPTP). Benzaldehyde was added at an approximate mol ratio of 50:1 benzaldehyde:TPTP. 24 h waschosen to demonstrate a completed degradation reaction. Labels: “circle” is benzaldehyde; “square” is suspected benzoic acid; “diamond” is suspected phenyl formate; and “triangle” is suspected phenol.

[0126] Figure 7 shows the1H-NMR tracked 24 h degradation of TPTP by Bi(OTfh and benzaldehyde (0.6-2.8 ppm). Labels: “3P” is 3-pentanone.

[0127] Figure 8 shows the proposed mechanism of degradation for TPTP by aromatic aldehydes and Bi(OTfh. From each point in the reaction which reaches the intermediate most like a Criegee intermediate of a BV reaction, there are two possible pathways. Reactions progressing to acid products are shown in the right hand pathway (originally in blue) and those progressing to formate products are shown in the left hand pathway (originally in red). One important note is that formate products shown can undergo hydrolysis or thermolysis to form phenol products that are observed through1H-NMR and GCMS.

[0128] Figure 9 shows TPTP degradation over 90 min comparing reaction rates of metal tritiates. ’ H-NMR spectra were taken with M(OTfh. 1:5 Catalyst:TPTP and benzaldehyde 50: 1 benzaldehyde:TPTP. The integral of TPTP, compared to a DCM reference peak, was tracked for 90 min as shown. Sc(OTfh showed the fastest reaction rate and most complete degradation by 90 min.

[0129] Figure 10 shows TPTP degradation over 120 min comparing reaction rates of aromatic aldehydes. ’ H-NMR spectra were taken with Bi(OTf)3 1:5 Catalyst:TPTP, 50:1 aromatic aldehyde:TPTP. The integral of TPTP, compared to a dichloromethane reference peak, was tracked for 120 min. p-Anisaldehyde was found to produce a faster rate of reaction.

[0130] Figure 11 is an overlay of TATP Peaks from 0 to 15 min for control versus Bi(OTf)3 catalysed testing. The top graphic shows the overlay of TATP peaks from degradation progression of 0 to 15 min in the control test without a Lewis acid catalyst. This demonstrates the lack of degradation with no catalyst, suggesting that the GCMS method is not skewing to false levels of degradation. The bottom graphic shows the overlay of TATP peak from degradation progression of 0 to 15 min in the Bi(OTf)3 catalysed testing. This demonstrates rapid degradation of TATP by the proposed mechanism.

[0131] Figure 12 shows the degradation of TATP by p-anisaldehyde and Bi(OTfh. This graphic shows the degradation of TATP based on area of the TATP peak from GCMS (Figure 11, 15 min and onwards shows no peak for TATP, i.e., complete degradation).Detailed Description of the Invention

[0132] It has been unexpectedly discovered that Lewis acid metal tritiates such as Bi(OTfh,In(0Tf)3, and Sc(OTf)s can act on cyclic peroxides to open the ring. When this reaction occurs between the Lewis acid and the organic peroxide, the ring opening is observed in a series of equilibrium reactions that are unsuitable for field relevant degradation. However, the ring opening that these Lewis acids catalyse provides an opportunity for a more optimised method of degradation.

[0133] In this work, simple aromatic aldehydes were chosen as they have known activity in Bayer-Villiger and Dakin oxidation reactions with hydrogen peroxide, low molecular weight and relatively low toxicity, making them attractive for field relevant application. Accordingly, the present invention relates to reactions of organic peroxides (specifically triacetone triperoxide (TPTP) as a non-explosive proxy for TATP) with aromatic aldehydes, catalysed by Lewis acid metal triflates.

[0134] Accordingly, the present invention relates to the use of one or more Lewis acids (particularly Bi(OTf)3, In(OTf)3, and Sc(OTf)3) to catalyse the degradation of one or more organic peroxides (particularly triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP)) by one or more aromatic aldehydes (particularly benzaldehyde or p-anisaldehyde).

[0135] Catalysts were selected based on their established use as a Lewis acid catalyst. Their performance at room temperature and ability to tolerate water were also examined. These characteristics are important for use in a field environment where conditions cannot be controlled

[0136] Rare-earth metal triflates (OTf; e.g., (1), below) have been widely researched due to their low toxicity, recoverability and potential for reuse. Low toxicity is an important characteristic as it reduces the risk to responders and bystanders and several triflate catalysts were selected for this study. Research has also been conducted on the use of ligands and polymer scaffolds to improve their water tolerance. Such modified triflate catalysts present an avenue for future research.

[0137] Triflates of bismuth, yttrium, scandium and indium were selected for the present study. ZrCh.SHiO, ZrCL has been identified as “green” Lewis acids and is thereby an attractive alternative candidates due to their low toxicity and moisture stability.

[0138] TATP is the cyclic trimer of acetone peroxide. It is the product of the reaction of hydrogen peroxide and acetone in an acid-catalysed nucleophilic addition reaction. There are several reaction conditions which influence the composition of the product of this reaction as there are several competing pathways for reaction. Under different conditions, the cyclic trimer (TATP), two dimers, one cyclic and one open chain, as well as an open chain monomer, can be formed as shown below.

[0139] Compound (1) is the cyclic trimer known as triacetone triperoxide (TATP), (2) is the cyclic dimer known as diacetone diperoxide (DADP), (3) is an open chain dimer named 2,2’ - dihydroperoxyl-2, 2’ -diisopropyl peroxide, (4) is a monomer called 2,2-dihydroperoxypropane.

[0140] The cyclic peroxides are only produced by the reaction under acidic conditions and the type of acid, its concentration and reaction temperature have very little influence on the product composition. The proportion of DADP increases with the concentration and strength of the acid with DADP not observed with formic or acetic acid catalysts. TATP spontaneously transforms to DADP in concentrated, strong mineral acid environments.

[0141] To date, it is known that four methods of destroying TATP are of interest where blow-in-place options are unavailable: acid protocol decomposition, thermal decomposition, dilution and subsequent burning, and catalytic decomposition.

[0142] Acid based degradation of TATP is the best understood method of neutralisation as it closely follows the mechanism of synthesis. By using strong acids to rebalance the equilibrium of the synthesis reaction, TATP can be broken down into acetone and peroxide.

[0143] An unfortunate consequence of this method is that it allows for the generation of DADP and reformation of TATP. DADP is less susceptible to acid-catalysed ring opening than TATP, so any method utilising strong acids needs to deal with its production in another way. One proposition is that a species which is readily oxidised by hydroperoxides could be introduced to inhibit DADP formation. Some acids such as HC1 can achieve this aim. However, the by-products are halogenated acetones which are very toxic and challenging to dispose of.

[0144] Acid-catalysed TATP degradation is also very exothermic and application of acid without causing detonation can be very challenging. In a field setting, it would be very dangerous to attempt acid catalysed degradation as concentrated strong acids are likely to lead to detonation and degradation takes an unpractically long time with dilute or weak acids.

[0145] Another commonly proposed mechanism to break down TATP is through thermolysis. Primarily driven by TATP’s lack of thermal stability, some research has proposed that TATP may be destroyed through burning or heating whilst in solution. The challenge lies in striking a balance between excess evaporation of any solvent and subsequent detonation of TATP and an unpractically slow thermal degradation whilst in solution.

[0146] It is challenging to conceive of a field-applicable method of utilising thermolysis to destroy TATP that does not require chemical expertise or complex, unwieldy equipment that is unsuitable for a field environment.

[0147] Whilst it is common practice in industry to destroy unwanted organic peroxides through dilution in organic solvents and burning in a pan, it is a very risky method of destruction. This is as when dissolved in most solvents, TATP does not contribute significantly to the vapor above the solution, meaning the solvent will be preferentially consumed and the solution will become saturated. In this case, there is risk of TATP crystallising, being rapidly heated by nearby burning and detonating. This risk scales dramatically with increased amounts of explosive, making burning an unreasonably risky method of destroying TATP.

[0148] In 2018, a field portable approach was proposed for the destruction of TATP through dissolving in diesel fuel and passing through a propane burner. There are several extreme risks associated with this method, including exposing explosively contaminated environments to open flames and high temperatures. Another significant concern is the large amount of solvent required to dilute to an appropriate level for burning. For instance, the 3 kg of white powder discussed in paragraph

[0006] would require in excess of 150 L of diesel in order to dilute / burn it effectively.

[0149] In theory, a catalytic method of TATP destruction has the best potential for field relevant use as small volumes of solvent and catalyst could produce safe, rapid, and logistically simple destruction.

[0150] Several potential pathways for catalytic destruction of TATP have been proposed, with the most promising being the exploitation of Baeyer-Villiger (BV) reactions which produce ester and ketone products from TATP. Using TiCU, researchers were able to produce effective degradation of TPTP before showing effective translation to TATP. This Lewis acid activated rearrangement of cyclic peroxides, providing a safer alternative to other destruction methods as it“locks away” peroxidic oxygen, preventing the inadvertent production of explosive materials in the decomposition process. Whilst a promising method of decomposition, TiCU is unsuitable for field application as it is not water-tolerant, requiring very strict anhydrous conditions and is not truly catalytic such that it is a participant and not regenerated.

[0151] Lewis acids are commonly used catalysts for organic reactions. Typically, the Lewis acid acts by coordinating to Lewis bases, withdrawing electron density, thereby increasing its electrophilicity. Then, once the reaction has taken place, the Lewis acid is able to dissociate from the product later in the mechanism. The primary reason for increasing the reaction rate is it turns an uncatalysed charge separation reaction into a charge transfer reaction with a lower activation energy.

[0152] A trait of Lewis acids that has become increasingly useful in recent years is their aqueous stability. This has primarily been driven by the undesirable hazardous waste that can be produced in the previously discussed reactions that utilise Lewis acid catalysis in organic solvents. Lewis acid catalysts which allow industrial processes to be performed without the production of hazardous waste are often referred to as “eco-friendly”. Performing synthetic protocols in aqueous media can significantly reduce the production of this hazardous waste in traditional industrial processes. Since the development of trifluromethanesulfonic acid in the 1950s, metal tritiates have been used in many organic reactions. Metal tritiates using elements such as gallium, bismuth, scandium and indium have become commonly used “eco-friendly” catalysis. Certain metal centres are preferred for different applications depending on factors such as cost, thermal stability, catalytic efficiency and aqueous stability.

[0153] A good example of a cheap and environmentally friendly Lewis acid is bismuth trifluromethanesulfonic acid (Bi(OTf)3). It forms as a water stable salt which stands apart from other tritiates due to its non-toxic character. It was found to be similar, if not more effective in catalytic effect to other metal tritiates for many reactions including Friedel-Crafts, Diels- Alder and Baeyer-Villiger oxidations.

[0154] Similarly, gallium trifluromethanesulfonic acid (Ga(OTfh) is known to drive reactions such as Friedel-Crafts alkylation. The acid is synthesised under reflux from gallium metal in excess trifluromethanesulfonic acid. Ga(OTf)3 displays good selectivity, high yields, good recyclability, and excellent aqueous and thermal stability. It is a good example of water stable catalyst which provides an opportunity to develop synthetic protocols in aqueous media.

[0155] In order to investigate the action of Lewis acid catalysis on TATP, safety has been a key barrier for experimental design and ease of investigation. TATP is very sensitive to shock, heat and friction, making it challenging to use safely within a laboratory environment. Anotherstorage consideration is TATP’s tendency to sublime and redeposit in containers. Due to these risks, experimental design with TATP can become very limited. Thus, TPTP has been utilised as a suitable analog for TATP degradation studies.

[0156] One of the primary benefits of this substitution are that TPTP is significantly less electrostatically sensitive than TATP, removing the requirement for specialised equipment, facilities, and clothing. TPTP is not initiated at 0.45 J of electrostatic energy, meaning normal levels of static charge accumulated on the body (approx. 0.02 J) are unable to initiate samples. This is opposed to TATP which can be detonated by just 0.02 J of electrostatic energy.

[0157] Another safety consideration is that TPTP sublimates extremely slowly at room temperature. It was found that less than 1% by weight was lost over 30 days left exposed at room temperature, meaning it is safe to store in standard threaded containers, unlike TATP.

[0158] Moreover, TPTP is known to react very similarly to TATP through primary mechanisms of acidic and thermal degradation. Accordingly, a fundamental extrapolation of this work is that any mechanism able to degrade TPTP should also be successful for TATP.

[0159] The most suitable starting point for investigating a Lewis acid catalysed breakdown of TATP is work in which it was identified that trifluromethanesulfonic acid based triflates have the potential to act as aqueous-stable catalysts for the breakdown of organic peroxide rings. TPTP again formed the basis of such work for the reasons discussed above, applying scandium, bismuth, and indium triflates in chloroform. Some TPTP degradation was shown over long periods of over 12 hours at room temperature, producing 3-pentanone (3P) as a major product (Figure J).

[0160] Whilst a full characterisation of the mechanism was never completed, it was noted that there were differences in the products of the Bi(OTf)s reaction, producing mainly 3P, while In(OTf)3 and Sc(OTf)3 both showed production of ring contraction products in addition to 3P. However, there were significant issues in a full accounting of products, with mass percentages calculated through GCMS out by up to 16.5%. An ABTS-based hydroperoxide investigation also produced an inconsistent characterisation of the reaction. One key issue encountered was a strangely high initial concentration of hydroperoxides. Whilst it required investigation, one explanation was that this was due to a poor de-acidification of the solvent, which initiated a Brpnsted acid-based ring opening of TPTP, producing unusually high “initial” values for hydroperoxide content.Triflate-based catalytic TPTP breakdown

[0161] Several trials of the three catalysts were conducted. Through unsuccessful tests withlow amounts of catalyst, it was found that all catalysts used in these conditions are sensitive to some water content in the chloroform. With excess catalyst - enough to coordinate to all water and have excess to catalyse the reaction, some breakdown was observed. However, no reaction under these catalytic conditions was observed to go to conclusion, being complete degradation of the TPTP. Figure 2 shows annotated examples of the spectra collected after 2 hours with excess catalyst. From these spectra, it can be seen that Bi(OTf)s acts very differently to In(OTf)3,and Sc(OTf)3. This is possibly due to its ability to change oxidation state. In(OTf)3, and Sc(OTf)3 produce similar results, with Sc(OTf)3 producing BV products of ethyl propanoate (EP) whilst In(OTf)3 only produces 3-pentanone (3P).

[0162] Figure 3 shows a reaction with excess Bi(OTf)3 after 64 hours. As the relative amount of TPTP present is very similar to that after 2 hours above, it supports the suggestion that this reaction will not progress to complete degradation of TPTP within useful timeframes. This is common to all the catalysts.

[0163] From Figure 2 and Figure 3 it seems most likely that the triflate catalysts are causing ring opening through a coordination reaction in a similar fashion to that proposed for TiCU. Bi(OTf)3 may act differently to In(OTf)3,and Sc(OTf)3, producing higher proportions of open ring intermediates as the open ring intermediate may be better stabilised by the oxidised bismuth than indium or scandium. It can be suggested that Sc(OTf)3 and In(OTf)3 follow the same reaction mechanism, but Sc(OTf)3 better stabilises the pathway towards the ester in the first step of the reaction, driving the equilibrium away from EP, the other BV product.

[0164] Another plausible explanation for the differences in products between the metal triflates is their sensitivity to water. As there was water present in all reactions, it can be proposed that a reaction in which water is a participant could drive the products towards 3P when water is consumed. In this case, a reaction more similar to BV re-arrangement becomes dominant, producing 3P and EP.

[0165] Bi(OTf)3 is hygroscopic by nature. This, as well as potential small differences in the starting amount of water, may explain the lack of a water peak in the bismuth NMR from Figure 2 in combination with the lack of EP as there is still water present to drive the primary reaction but its NMR signal has been shifted out of the relevant region.

[0166] When considering these reaction pathways, it is most plausible that hydroperoxides, which cannot be observed by NMR in this region, are being produced. This is evidenced by tracking of hydroperoxides with ABTS assays and the lack of oxygen accounting present in all NMRs.ABTS testing of catalytic breakdown

[0167] To assess the production of hydroperoxides by the triflate catalysed degradation mechanism, ABTS assays were taken at various time points in the reaction. One example of this tracking, showing the growth of hydroperoxide concentration through degradation by Bi(OTf)3, is shown in Figure 4. Tracking from 30 min to 90 min, in 30 min intervals, the amount of oxidised ABTS, indicative of hydroperoxide concentration, grows significantly over this time. This supports the suggestion that the mechanism of degradation for metal triflates in isolation produces hydroperoxides. When taken with the NMR results, it can be suggested that these hydroperoxides are those with the potential to recyclize into explosive products such as DPDP.Mechanism of degradation

[0168] With the data collected from the degradation of TPTP with metal triflates - designated “M(OTf)3” for ease of discussion, it can be surmised that several competing reactions are occurring. It is most plausible that the preference for these reactions is driven by the balance of the effects of water content, the activity of each catalyst and their associated water tolerance. From this, two main reactions mechanisms were proposed, seen in Scheme 1, below.

[0169] The above mechanisms show two potential pathways of degradation for TPTP and a Lewis acid. Mechanism (1) is closely modelled off the degradation pathway of TPTP under Brpnsted acid catalysis in which the reaction products are the same as the reaction precursors. This is possible due to the trace presence of water in the solvent. Mechanism (2) is modelled off a reaction pathway suggested in the Lewis acid catalysed breakdown of TPTP by TiC

[0170] One key limitation of these mechanisms in the field relevant degradation of cyclic peroxides is that they can be reversible, forming an equilibrium and never being driven to completion. This can prevent the complete degradation of a bulk explosive, a crucial objective of a field relevant degradation solution. Another issue is the production of hydroperoxides which can form ring contraction products such as DPDP, the dimer of the cyclic pentanone peroxide family. DPDP is a major product of the Brpnsted acid catalytic breakdown of TPTP - a method deemed unsuitable as the ring contraction products of TATP are potentially a more sensitive and equally powerful explosive.Scheme 1 - Proposed primary mechanisms for the degradation of metal triflates

[0171] Accordingly, it is apparent that metal tritiates can catalyse some degradation of TPTP. This likely occurs through multiple competing reactions, the most likely of these representing analogies to BV processes and the degradation pathway of TPTP under Brpnsted acid catalysis. It was also known that metal tritiate catalysed degradation produces significant quantities of hydroperoxides.

[0172] It had become clear that in isolation, metal tritiates may only catalyse partial degradation through equilibrium reactions and produce unwanted hydroperoxides. This makes them unsuitable for use as a field relevant degradation option. However, the ability for a water- tolerant Lewis acid to catalyse ring opening of cyclic peroxides provided an avenue for further investigation. As they can catalyse the production of in-situ hydroperoxides, it was plausible that an oxidation reaction utilising these hydroperoxides could be used to consume the oxygen, rendering the cyclic peroxide unusable for further explosive threat. As noted above, it was known that Lewis acid catalysed Bayer-Villiger and Dakin oxidation reactions can consume hydroperoxides and results in the possibility of utilising such oxidation reactions for the degradation of TPTP. Simple aromatic aldehydes were chosen as they have known activity in BV and Dakin oxidation reactions with hydrogen peroxide, low molecular weight and relatively low toxicity, making them attractive for field relevant application.

[0173] To investigate the action of aromatic aldehydes on TPTP when catalysed bymetal triflates, benzaldehyde was chosen as an initial candidate due to its simplicity and previous use in BV and Dakin oxidation studies with hydrogen peroxide.

[0174] To determine general feasibility of the reaction, ' H-NMR was used to track degradation for Sc(OTf)s, Bi(OTf)3, and In(OTf)3. These were prepared at 1:5 mol ratio catalyst:TPTP. Benzaldehyde was added at an approximate mol ratio of 50: 1 benzaldehyde:TPTP. Initially, two time intervals were taken at 20 min and 4 h. The 1:5 ratio was chosen to represent moderate catalytic conditions. The 50:1 ratio was chosen as a molar excess with easily deliverable volumes on the1H-NMR scale.

[0175] Shown in Figure 5, all catalysts acted to significantly degrade the TPTP in the 4 h time period. When compared to the excess catalyst experiments related above, achieving near complete degradation with 1:5 catalyst ratio is a significant improvement. This suggested that a unique and promising reaction was occurring with addition of benzaldehyde.

[0176] Once this unique reaction was identified, the ’ H-NMR degradation tracking of the Bi(OTf)3 reaction was repeated in an attempt to characterise the reaction products. The spectra measured at completion, 24 hours, are shown in Figure 6 and Figure 7.

[0177] When considering Figure 5, it is important to note that the major products of all three reactions are functionally identical. Figure 6 and Figure 7 show annotated spectra of a completed reaction of Bi(OTf)3 and comparison spectral region for benzaldehyde taken at 24 h. From Figure 7, we can see that one primary product is 3 -pentanone. It then appears that benzaldehyde is being consumed to produce oxidation species. It can be suggested, by comparing peak positions with published ’ H-NMR values for benzoic acid, phenyl formate and phenol, that these oxidation species are present. This is consistent with the oxidation products of Dakin oxidation.

[0178] The ' H-NMR data align with the annotated peaks in Figure 6, notable overlaps are the peaks at 7.24 ppm, likely corresponding to both phenyl formate and phenol, and the peaks between 7.37 and 7.45 ppm, likely corresponding to both phenyl formate and benzoic acid. There is also likely a hidden peak under the benzaldehyde triplet at 7.6 ppm which corresponds to benzoic acid.

[0179] Calculation of approximate molar ratios of products is challenging for the benzaldehyde-based products. Firstly, it is unfeasible to perform experiments in an anaerobic environment meaning the benzaldehyde may have been oxidised to benzoic acid via the air rather than through the degradation mechanism. One other key consideration is that several of the peaks in the 7.1-8.1 ppm region overlap significantly, making theintegration of unique peaks very challenging. One available observation was the production of 3-pentanone compared to TPTP loss, total growth was 3.OO+O.3O for all tests.

[0180] To support theXH-NMR data, a GCMS experiment was run using the products of a Bi(OTf)3, benzaldehyde and TPTP reaction in chloroform. The catalyst and aromatic aldehyde were in the same ratios and reaction conditions as theXH-NMR experiment. The chromatogram from this GCMS run is not shown, however may be readily rationalized as follows. Bi(OTf)s was prepared at 1:5 mol ratio catalyst:TPTP. Benzaldehyde was added at an approximate mol ratio of 50: 1 benzaldehde:TPTP. There are four main peaks that can be easily identified: 3-pentanone, benzaldehyde, phenol and benzoic acid. The absence of a peak corresponding to the known retention time of TPTP under the same GCMS conditions (11.54 min) suggests that the TPTP has been effectively consumed supporting conclusions made from theXH-NMR data.

[0181] An interesting observation from the GCMS data is the lack of phenyl formate in the product characterisation. As phenyl formate is rapidly undergoes hydrolysis and thermolysis to phenol when heated, it can be suggested that phenyl formate present could be degraded in the injection port of the instrument. An injection port temperature of 100 °C is known to be the ideal temperature for bringing TPTP into the gas phase whilst preventing thermal breakdown of cyclic peroxides and so cannot be reduced.

[0182] With the1H-NMR and GCMS product characterisation and evidence of similar stoichiometry, there is support for the suggestion that TPTP degrades via a reaction similar to Dakin oxidation in the presence of a triflate Lewis acid catalyst and benzaldehyde. However, if this is the case, the production of hydroperoxides as noted above should not be occurring in this reaction. To test this, ABTS assays were conducted to track the concentration of oxidised ABTS over 6 h.

[0183] A single reaction was prepared with 20 mM TPTP, benzaldehyde: TPTP at 50: 1, Bi(OTf)3:TPTP at 1:5. The total volume of this reaction was 2 mL. 0.1 mL aliquots of this reaction were taken for ABTS assays at the hour for 6 h. In the process of adding ABTS and HRP, the TPTP solution was diluted 15x. This gives a maximum availability of peroxides in the solution of 4 mM, 3 per TPTP molecule. The results from these ABTS assays showed that the concentration of hydroperoxides does not exceed 0.01 mM, or 0.25% of the available hydroperoxides from TPTP. This, along with the 0 mM concentration of hydroperoxides upon reaction completion, supports the suggestion that the reaction is not producing hydroperoxides. The ABTS oxidation observed is likely due to open ring products at instantaneous points through the degradation mechanism.

[0184] It is known that altering the para-substituted functional groups of the aromatic aldehyde can have dramatic effects on the outcome of the products of a Dakin oxidation. To support the hypothesis that TPTP degradation is occurring through a unique form of Dakin oxidation where hydrogen peroxide is replaced with peroxides from an opened cyclic peroxide ring, benzaldehyde can be substituted with p-anisaldehyde. If the degradation is occurring through a form of Dakin oxidation, adding a methoxy group as a para substituent should drive the reaction towards a higher proportion of formate / phenol product when compared to the carboxylic acid product.

[0185] To test the products of p-anisaldehyde in substitute for benzaldehyde, an experiment was conducted based on the1H-NMR degradation tracking method described above i.e., 0. 5mL of 20 mM TPTP was used for all tests. From there, Bi(OTf)s at 1:5 catalyst:TPTP was added alongside a 50: 1 aldehyde:TPTP excess. This was used to compare the effects of p-anisaldehyde and benzaldehyde.

[0186] As noted, there was a dramatic increase in the proportion of phenol produced as an oxidation product when substituting benzaldehyde for p-anisaldehyde. This is consistent with the literature for Dakin oxidation as the methoxy group acts to donate electron density to the aromatic ring, stabilising the migration of the aromatic moiety. The electronegative oxygen’s electron- withdrawing inductive effect is dominated by the oxygen’s lone pair electron-donating resonance effect. Consequently, the methoxy group acts primarily as an electron donating group.

[0187] The increase in formate / phenol product with the switch to p-anisaldehyde further supports the hypothesis that TPTP degradation is occurring through a Dakin oxidation mechanism.

[0188] The product characterisation of the p-anisaldehyde and Bi(OTf)3 reaction is also supported by GCMS results. As a component of reaction characterisation, a 6 h GCMS degradation track was performed for p-anisaldehyde.

[0189] It is unusual that p-methoxyphenyl formate was present in the GCMS products when as noted above, this was not the case for phenyl formate produced in the benzaldehyde reaction. To confirm this observation, p-methoxyphenyl formate was synthesised as described above. This synthesis product was then used to produce a gas chromatogram and mass spectrum. The results demonstrate both stability through the GCMS method and consistency in retention time to aid in the characterisation. It is plausible that the p- methoxyphenyl formate is more resistant to hydrolysis or thermolysis than the small quantities of phenyl formate observed from the benzaldehyde reaction.

[0190] To note, the sum of the proportional areas calculated for the fragment peaks is three times as large as the loss in peak area of TPTP. This is consistent with the understanding of a form of Dakin oxidation, where for each mole of TPTP degraded there is three moles of oxygen consumed through the production of either formate or acid products.Proposed mechanism

[0191] When considering a mechanism for the observed degradation of TPTP, there are several influential pieces of evidence that show the degradation reaction is consistent with the suggestion that it is occurring through Dakin oxidation: the product characterisation of all observed reactions is predictable and consistent; the stoichiometry of key products is consistent with literature understandings of Dakin oxidation (3 moles of 3-pentanone and 3 moles of formate / phenol + acid product for each mole of TPTP); the reaction does not produce hydroperoxides; the increased proportion of formate product compared to the acid product with the switch to p-anisaldehyde can be predicted by a Dakin type oxidation mechanism.

[0192] Figure 8 shows a plausible mechanism to explain the degradation of TPTP in a reaction similar to Dakin oxidation. From each point in the reaction which reaches the intermediate most like a Criegee intermediate of a BV reaction, there are two possible pathways. Reactions progressing to acid products are shown in blue (right hand path) and those progressing to formate products are shown in red (left hand path). One important note is that formate products shown can undergo hydrolysis or thermolysis to form phenol products that are observed throughXH-NMR and GCMS.

[0193] The mechanism starts with the activation of the aldehyde carbonyl bond by coordination to the Lewis acidic centre, and ring opening of the TPTP caused by simultaneous coordination. This if followed by nucleophilic attack of the peroxide onto the more electrophilic carbonyl carbon atom, creating an intermediate product most similar to a BV Criegee intermediate. Then, either through an epoxide intermediate and subsequent rearrangement to form the formate product or through migration of the hydrogen to form the acid, Fragment A is released. Having removed one oxygen, the reaction can continue until all peroxides are consumed.

[0194] The mechanism in Figure 8 is plausible because it is now known: that metal triflate catalysts have the capacity to catalyse the ring opening of TPTP; that Lewis acids such as metal triflates are effective selective catalysts for reactions similar to Dakin and BV oxidation; the mechanism explains the characterisation and stoichiometry of reactionproducts observed; and the mechanism is able to predict the proportion of reaction products observed in testing.

[0195] Thus, a reaction similar to Dakin oxidation can be used in combination with Lewis acid ring opening of TPTP to degrade the cyclic peroxide. Through this process, explained with a proposed mechanism, the peroxides are consumed and cannot be reformed into explosive products. Another benefit of this reaction mechanism is that aromatic aldehydes can be used as a solvent for TPTP, meaning the degradation reaction can be easily driven to completion with a simplistic two -ingredient degradation application.

[0196] With further characterisation of the ideal conditions of this reaction, it has promising potential to provide a field relevant degradation reaction for cyclic peroxides. To provide this characterisation, there are several features of the reaction that must be quantified. The heat of reaction, ratio tolerances for catalyst and aromatic aldehyde, and tolerance to water are all properties that must be explored in order to propose a field relevant method of degradation.

[0197] The general goal for a field relevant application is to use the aromatic aldehyde as a solvent for dissolving an organic peroxide explosive. Then, utilising the solvent and a water tolerant Lewis acid through the reaction identified above, the organic peroxide explosive can be degraded, rendering it safe. For this reaction to be applied in a field relevant setting, certain characteristics need to be quantified. Most particularly, it was important to determine the most suitable Lewis acid and aromatic aldehyde, along with their relative proportions.

[0198] To choose the best metal triflate for use as a Lewis acid catalyst in the degradation of TPTP, a set of criteria for a good candidate need to be established, from which a decision-making process can be followed: heat of reaction; rate of reaction; general applicability (z.e., cost, toxicity, tolerance for ratios, etc.); and which proportions for a given quantity allow prediction of the rate of reaction as a controlled protocol.

[0199] Heat of reaction is an important consideration for field relevant application of the mechanism proposed. To compare the heat of reaction for each Lewis acid and provide an approximation of whether the reaction is at an appropriate level of heat, DSC testing was conducted in accordance with the protocols described above.

[0200] The heat sink capacity of the aromatic aldehyde is an important consideration in the inventive process. Benzaldehyde was chosen for initial testing. Table 1 shows the results for average J / g for the reaction in reference to the amount of TPTP. This was calculated from four tests with each catalyst. Reactions were considered complete when the energychange required to maintain temperature was constant - i.e., the reaction was no longer producing heat. There seemed to be no correlation between the heat and amount of TPTP, amount of catalyst, or the molar ratio of the two.Table 1 - Average exothermic energy of each metal triflate as calculated by DSC

[0201] For comparison, one can examine the worst-case scenario of a reaction based exothermic detonation. This suggests that 2000J / g is an approximate guide for the upper bound of safe heat of reaction in a worst-case scenario. This heat poses the threat that degradation reactions could cause detonation of nearby undissolved explosive. In a field relevant setting, this poses unacceptable risk. This casts doubt over In(OTf)3, which produced individual runs with exothermic energy above safe levels unlike Bi(OTf)3 and Sc(OTf)3. Further work required to scale up this heat testing to field relevant amounts of materials will likely be done in a bomb calorimeter.

[0202] To compare the effects on reaction rate of changing the metal triflate Lewis acid,1H-NMR degradation tracking was undertaken, i.e., 0.5 mL of 20 mM TPTP was used for all tests. M(OTf)3 was at 1:5 catalyst:TPTP alongside a 50: 1 benzaldehyde:TPTP. A fixed volume of dichloromethane was added to each reaction to act as an inert reference peak for integration. Spectra were taken at 5-minute intervals for 60 min, followed by a confirmatory spectrum at 90 min. The integral of the TPTP was tracked. The results of this tracking are shown in Figure 9. From these data, Sc(OTf)3 showed the fastest reaction rate, followed by In(OTf)3then Bi(OTf)3.

[0203] In Figure 9, it is salient to note that whilst there is a slight difference in rate of reaction, all reactions progressed to less than 30% TPTP in less than an hour. This provides a significantly faster rate of reaction than any previously suggested applicable degradation method. It is assumed that the rate of reaction differences for each catalyst applies across aromatic aldehydes.

[0204] There are several factors other than heat and rate of reaction that must beconsidered when choosing an ideal Lewis acid. Once the generalised results of the heat experiments referred to above have been validated, more definitive decisions about the most applicable Lewis acid can be made. For now, if we assume that results hold for application scale testing, the only metal triflates considered to be consistently safe would be Bi(OTf)s and Sc(OTf)3.

[0205] All three Lewis acid choices are generally considered non-toxic. As there is no significant difference in product characterisation when changing catalyst, toxicity was not a relevant factor when choosing between them. When testing, all catalysts showed activity down to 1:25 Catalyst:TPTP molar ratio with no significant difference in the reduction in reaction rate. Lower molar proportions of catalyst were not tested due to the availability of TPTP and the lower bound for accurate mass measurements of catalyst. All catalysts showed a similar tolerance to water.

[0206] One of the primary considerations for field relevant application is the ease of access and cost of materials. Comparing bismuth and scandium triflates where heat and rate of reaction suggest that scandium is a preferable catalyst cost will likely drive industrial decision making. In analytical quantities, Sc(OTf)3 is significantly more expensive at approximately five-times the price of Bi(OTf)3. Bi(OTf)3 has the most application in industrial processes and consequently the most well established large scale production. If the cost and supply of Sc(OTf)3 could be improved, it may be the best candidate for field relevant application. However, as it is significantly cheaper and fulfils requirements of low heat and fast reaction rate, Bi(OTf)3 provided the most practical Lewis acid catalyst for further exploration and testing.

[0207] As identified, Bi(OTf)3 is likely to be the best Lewis acid catalyst candidate for field relevant degradation. From there, an aromatic aldehyde needs to be chosen to act as a solvent and oxygen trap for TPTP degradation. To this end, liquids of low volatility appear ideal. As above, benzaldehyde and p-anisaldehyde were tested as viable options. The proposed mechanism for degradation is not limited in its function to these two choices, but they do provide low cost, commonly available options.

[0208] For extended investigation, vanillin (4-hydroxy-3-methoxybenzaldehde) was tested as an alternative aromatic aldehyde. As tracked by GCMS, vanillin was able to produce reliable degradation. Whilst it was able to produce degradation at similar reaction rates to benzaldehyde and p-anisaldehyde, is a solid at room temperature and does not provide the option for doubling as a solvent. Degradation methods utilising vanillin would require an additional material to act as the solvent. Vanillin is also far more expensive thanthe alternatives, at nearly ten-times more expensive than benzaldehyde by mass. Accordingly, vanillin was discounted as a candidate for aromatic aldehyde in field relevant application.

[0209] In choosing between benzaldehyde and p-anisaldehyde, the same criteria used to compare catalysts were deemed appropriate metrics to judge aromatic aldehyde suitability: heat of reaction; rate of reaction; and general applicability (z.e., cost, toxicity, tolerance for ratios, etc.). For this testing, Bi(OTf)s was used as the catalyst as deemed most suitable for further investigation.

[0210] To compare the heat of reaction between p-anisaldehyde and benzaldehyde, the DSC testing for Bi(OTf)3 and benzaldehyde was repeated with a substitution for p- anisaldehyde. The p-anisaldehyde and Bi(OTf)3 DSC tests were conducted six times to verify results. There was no measurable heat produced by any reaction. To confirm that the reaction was progressing in these conditions,1H-NMR in MeCN-z / 3 was used to analyse the products of a reaction at 20 min of progression. The reaction progressed significantly, with most TPTP having degraded. If the reaction had only begun once in the NMR tube, i.e., the reaction was not progressing in the DSC crucible, the reaction would not show the level of progression observed. This supports the suggestion that the reaction was occurring in the DSC crucible. Thus, the lack of heat measurement can be attributed to low heat of reaction, not a lack of reaction progression.

[0211] These results suggest that the p-anisaldehyde reaction has a significantly lower heat of reaction than the comparable reaction with benzaldehyde. If there is still heat being produced by the reaction, another important comparison is the specific heat of the two aromatic aldehydes. By the Joback method, benzaldehyde has an ideal gas heat capacity of 155.23 J mol1K1. p-Anisaldehyde has a comparably higher ideal gas heat capacity of 215.85 J mol1K1. Whilst this numerical approximation does not represent the real liquid phase heat capacity at room temperature, it allows for the comparison to be made, suggesting p-anisaldehyde would be a more effective heat sink for a reaction when acting as the solvent.

[0212] The rate at which TPTP can be degraded is a key factor in designing a field relevant degradation strategy. To compare the rate of reaction between benzaldehyde and p- anisaldehyde, ’ H-NMR tracking with 20 mM TPTP in acetonitrile was used. Acetonitrile was substituted for de-acidified chloroform to test the activity of the reaction in a different solvent, confirming previous assumptions that chloroform or any related acid is not active in the reaction mechanism. Bi(OTf)3 was at 1:5 catalyst:TPTP and aromatic aldehydes wereprepared at 50: 1 aromatic aldehyde :TPTP. The two reactions were tracked for 2 h to determine the change in rate of reaction when altering the aromatic aldehyde. Figure 10 shows this tracking as a percentage of TPTP present, calculated through integral analysis referenced to a fixed volume of DCM.

[0213] From Figure 10, it can be seen that p-anisaldehyde acting as the aromatic aldehyde produces a faster rate of reaction, with less than 10% of TPTP remaining after just 40 min. Benzaldehyde takes approximately 60 min to achieve the same degradation. In this way, it can be said that -anisaldchydc improves the degradation of TPTP over benzaldehyde by 33.3%.

[0214] This difference in rate of reaction could be explained by the difference in rates between the epoxide intermediate formation and subsequent rearrangement to form the formate product and the migration of the hydrogen to form the acid. If the formation of the acid from the Criegee-like intermediate is the rate limiting step for the degradation of TPTP, it would follow that diversion down the pathway of formate production would increase the rate of degradation.

[0215] If used as a solvent for field relevant testing, there are several considerations for choosing between the two aromatic aldehydes. Benzaldehyde is readily oxidised to benzoic acid in aerobic storage. This benzoic acid forms a white crystalline layer in storage bottles and on surfaces when left exposed to oxygen. If used as a solvent for the degradation of organic peroxide explosives, also white powders, this could pose challenges for EOD personnel in identifying materials. As it is preferable that the application of the degradation method is as simple as possible, an added complexity of identification of white powder is not ideal, - Anisaldehyde does not produce 4-methoxybenzoic acid as readily in normal storage or operation conditions.

[0216] For both aromatic aldehydes, their toxicity and that of the products of their respective reactions are low. The main products of the benzaldehyde reaction are benzoic acid and the ketone associated with the organic peroxide for TPTP, 3-pentanone. Some of the benzoic acid is replaced by the phenol / formate product when benzaldehyde is substituted for p-anisaldchydc. The most significant exposure effects for these chemicals are skin irritation, eye damage or inhalation related irritation.

[0217] Both aromatic aldehydes are readily available for industrial applications and are low cost. Unlike for the Lewis acid catalyst decision making, this would not be a significant factor for field relevant application.

[0218] Due to its increased rate of reaction, unmeasurably low heat, and betterproperties for field relevant application, p-anisaldehyde can be considered the more suitable aromatic aldehyde for further investigation and application.

[0219] It can be concluded that a BiiOTfjs and p-anisaldehyde based degradation method provides the most suitable candidate for further investigation pursuing field relevant application. Results suggest that this reaction produces very low levels of heat. It is also known that the reaction can degrade TPTP very rapidly, producing >90% degradation of TPTP in approximately 40 min. This rate of reaction would likely increase when using p- anisaldehyde as the solvent as it would increase the proportion of aromatic aldehyde available, driving the reaction towards the degradation products.

[0220] As this research has been based on the reaction’s application to TPTP, an analog molecule for TATP, the next consideration is the applicability of the suggested reaction to degrade TATP.

[0221] The ideal solution for a field relevant degradation method for organic peroxide explosives is one that can apply easily to the full family of organic peroxide threats. The degradation method discussed above has the potential to produce this outcome. The first step in testing this application is examining its applicability to TATP. If successful, this testing will support suggestions for further research to inform field relevant application. The family of organic peroxide explosives considered for analysis comprises hydrogen peroxide, ditertbutyl peroxide, triacetone triperoxide (TATP), diacetone diperoxide (DADP), methyl ethyl ketone peroxide (MEKP) and hexamethylene triperoxide diamine (HMTD).Application to TATP

[0222] To determine the effectiveness of the Dakin oxidation-based degradation method on TATP, GCMS testing was chosen as the most accessible method of degradation tracking. This was primarily due to availability of equipment at DST Edinburgh. Acetonitrile was chosen as a solvent to remove the requirement for deacidification of chloroform. Also, the change in solvent provided a secondary effect of demonstrating that chloroform was not required in the mechanism of degradation confirming previous assumptions in the mechanistic understanding. GCMS testing of this degradation was conducted as described. p-Anisaldehyde and Bi(OTf)3 were used as they are the most suitable candidates for further investigation of the method of degradation.

[0223] Added complexity to the GCMS testing of a water and hexane wash was required due to the solubility of the catalyst in acetonitrile. This wash method aimed to remove the catalyst whilst retaining TATP for the purposes of degradation tracking. Asidentified previously, if the catalyst is present in the injection port, it is very likely to instantaneously degrade any TATP present, skewing results towards faster degradation.

[0224] From Figure 11 and Figure 12, one can see the rapid degradation produced by the proposed mechanism with TATP. The lack of TATP degradation in the control experiment demonstrates that the method is not causing degradation through the GCMS testing, i.e., in the injection port. The rapid degradation observed is consistent with the understanding that TATP is more easily degraded than TPTP due to the lesser steric hinderance from the ethyl / methyl arms.

[0225] One limitation of the GCMS testing conducted is the incomplete product characterisation due to the water and hexane wash method. Whilst retaining TATP and other aromatic aldehyde products, a full product list cannot be compiled. The main product observed in testing was 4-methoxyphenyl formate, consistent with the proposed mechanism. From this, it can be assumed that the mechanism for TATP degradation follows the logical translation from that proposed for TPTP (see, e.g., Figure 8).

[0226] There was no aromatic carboxylic acid product observed. This could be explained by TATP degradation through reaction with p-anisaldehyde, catalysed by Bi(OTf)s, more easily following the red (left hand pathway) mechanisms outlined (with reference to TPTP, not TATP) in Figure 8 leading to the formate product. However, the possibility of the acid product being removed throughout the process, perhaps in the wash, cannot be ruled out. For the six oxygen atoms in each TATP molecule, peak areas for the formate product only account for 2.3 oxygen atoms of the TATP degraded. It can be assumed that 3.7 oxygen atoms are being used in the formation of the carboxylic acid product which is being removed at some point in the analysis method. A full characterisation of products would be able to confirm this assumption.

[0227] There is sufficient evidence to suggest TATP can be rapidly degraded by the mechanism proposed. With this information, the process of developing a field relevant application of this mechanism can continue.Application to other organic peroxides

[0228] Additional organic peroxides to assess include hydrogen peroxide, ditertbutyl peroxide, diacetone diperoxide (DADP), methyl ethyl ketone peroxide (MEKP) and hexamethylene triperoxide diamine (HMTD). As the mechanism proposed works to degrade hydroperoxides and has been observed to open the ring of TATP and TPTP, it can be assumed that it would rapidly degrade DADP through a similar mechanism, with the methodof ring opening applying across the same carbon-oxygen ring structures.

[0229] With significant literature evidence of Dakin action on hydrogen peroxide, it can be assumed that a reaction mechanism similar to Dakin oxidation would also apply to organic peroxides lacking a ring structure. For hydrogen peroxide, ditertbutyl peroxide and MEKP, the lack of supporting ring structure means their peroxide oxygens are more easily available for attack. From this, it can be assumed that these three organic peroxide explosives could be degraded through the same mechanism as TATP. The same logic of translating the known mechanism of action does not apply to HMTD as the nitrogencontaining ring structure may pose challenges for ring-opening. However, the ability of TiCk to degrade TPTP and TATP was shown to apply to HMTD. This indicates that the Dakin oxidation-like degradation reaction may also translate to HMTD.

[0230] Further research is required to assess the applicability of the proposed reaction on this family of organic peroxide explosives.

[0231] The heat of reaction of TPTP, p-anisaldehyde and Bi(OTf)3 was not measurable during this research. This may be due to extremely low levels of heat production, in which case larger scale testing is required to confirm the true heat of reaction. From the results gathered and observations during testing, it can be assumed that the reaction is safe on very small scales. As TATP appears to react more rapidly than TPTP, it is possible that the heat of reaction is higher. Further research is required to assess the heat of reaction on small and large scales when reacting with TATP and other organic peroxide explosives.

[0232] Reasonable water tolerance of any catalyst to cyclic peroxide degradation is a key aspect of any field-relevant approach. Typically, when metal compounds are added to solutions containing water, hydration occurs immediately with metal centres being completely coordinated to water molecules. This phenomenon was observed in the testing conducted without aromatic aldehydes. During this testing, it was regularly observed that with low amounts of catalyst, ring opening of TPTP and any subsequent degradation was rare and inconsistent. If a water peak was observed inXH-NMR testing, it was consistently coupled with a lack of degradation. However, with large amounts of catalyst, in excess of any water present, there was a lack of defined peaks associated with water and there was more consistent degradation of the TPTP. This is consistent with literature understandings of water stable Lewis acid activity, in that once the water has been consumed through coordination with metal centres, the remaining active Lewis acid can act to catalyse a degradation reaction of the TPTP.

[0233] When moving to reactions with participatory aromatic aldehydes, thisphenomenon was not observed. While no effort was made to minimise water content in the aromatic aldehydes used, water peaks inXH-NMR data were never observed. This could be due to changes in environmental conditions such as atmospheric humidity, however, more likely is the water is interacting with the reaction as a participant or in a side reaction with the aromatic aldehyde. As the reaction progresses as expected, this was not considered an issue. It has also been previously reported in literature that metal triflates have a higher affinity to coordinate to aldehydes than water, so it is possible that incorporating an aldehyde diverts coordination of water away from the metal triflates, allowing the metal centres to continue as catalysts for the reaction.

[0234] Despite these observations of water tolerance for the aromatic aldehyde-based reactions, it was challenging to conduct formal testing of water tolerances. At the scales of safe laboratory testing, when the smallest practical amount of water or D2O was added to any reaction mixture in the microlitre range, it was immiscible with the aldehyde and organic layer, creating phase separation. As the metal triflates are soluble in water, this likely dragged the catalyst out of the organic phase and prevented progression of the reaction. When this testing was conducted, an upper bound for water tolerance could not be measured. Further investigation is required to confirm the assumption that the solubility of water in an aromatic aldehyde solvent is lower than the upper bound for the water tolerance of the degradation reaction with associated Lewis acid catalyst.

[0235] More research could be conducted to assess the tolerances for the amounts of reagent. Most of the testing conducted in this research was done at 1:5 catalyst:TPTP, or 1: 15 catalyst:peroxide. Further testing may provide evidence of the possibility of reducing catalyst proportions below 1: 15 catalyst:peroxide. Testing assessing the possibility of reducing the excess amount of p-anisaldehyde is also required to inform the use case presented below.

[0236] Finally, testing needs to be conducted on larger scales of explosives to assess the feasibility of field relevant application on amounts of explosive from the hundreds of grams up to kilos. This testing poses significant hazards and would be the most resource intensive of the further testing proposed. However, in order to inform EOD operating procedures, the possibility of unforeseen interactions occurring due to the reaction’s larger scale needs to be investigated.

[0237] This work has produced several key findings, breaking new ground on the safe degradation of organic peroxide explosives. Through the exploration of the mechanism of ring opening by water- tolerant Lewis acids, it was identified that metal triflate Lewis acidscan be used to catalyse the oxidation of aromatic aldehydes by organic peroxides. This reaction, proposed to be similar to Dakin oxidation, is a unique reaction not known in the literature. There is no previous study of Lewis acids being used to catalyse a reaction similar to Dakin or BV oxidation utilising peroxides from cyclic molecules instead of hydroperoxides.

[0238] This process was identified to act as a degradation mechanism for TPTP, an analogue molecule for TATP. The mechanism of degradation was then shown to effectively translate to degrade TATP.

[0239] This understanding will act as the foundation for the further work, which may inform the production of a field relevant degradation method for all organic peroxides. This has significant ramifications for Australia’s national security capability, providing safe tools for EOD responders to address explosive threats.Materials and Methods

[0240] All chemicals and solvents were of analytical grade unless otherwise noted. All triflate catalysts (Bi(OTf)3, In(OTf)3, and Sc(OTf)3) were commercially-sourced. The TPTP used was synthesised internally. Due to the age of the sample and some concerns of contamination, NMR and GCMS analysis was conducted to determine purity. It was determined that the TPTP sample had not degraded in any measurable way since synthesis and was pure enough for further testing.

[0241] 2,2’ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) or ABTS is a compound commonly used in the tracking of reaction kinetics using specific enzymes such as horseradish peroxidase (HRP). With this enzyme, ABTS acts as an electron donor for species such as hydroperoxides. When oxidised, ABTS+has a different UV absorbance, producing a tri-peak absorbance spectra from 600-900 nm, and distinct, strong maxima around 420 nm. By tracking this strong maxima, the amount of oxidised ABTS in a reaction via a UV- Visible Spectrophotometer can be calculated by back-calculating from known extinction coefficients. From this, the concentration of hydroperoxides in a reaction can be tracked. The extinction coefficient of ABTS+at 420 nm is 3.6 x 104M1cm1.

[0242] Benzaldehyde is readily oxidised to benzoic acid. To remove contaminated acid, it was washed with sodium hydroxide, acidified with any acid then washed with saturated sodium sulfite and water. This was followed by drying with magnesium sulfate. Then, the benzaldehyde was purified via vacuum distillation under nitrogen. Once purified, it is stored under nitrogen in an opaque container.

[0243] / ^-Anisaldehyde can be purified via a similar method. This was deemed unnecessary as impurities in purchased materials could be accounted for in testing, p- Anisaldehyde was stored under nitrogen in opaque containers to prevent UV catalysed breakdown.

[0244] p-Methoxyphenyl formate was required for comparison with GCMS results. It was synthesised as follows. Acetic anhydride (15 mL) was added to a 100 mL two- necked flask and cooled to 0 °C. Then, formic acid (7.6 mL) was added and stirred at room temperature for 10 min. The mixture was then stirred and heated for 1 h at 60 °C. Once cooled to room temperature again, 4-methoxyphenol (2.5 g, 20 mmol) and NaHCOs (3.4 g, 40 mmol) were added. The mixture was then stirred overnight at room temperature. The mixture was extracted with DCM three times and washed with water three times before being dried over anhydrous Na2SO4. The mixture was filtered and concentrated under reduced pressure. From there, the residue was purified by flash chromatography with silica gel using an eluent of hexane-AcOEt (20: 1). The mixture was filtered and concentrated via rotary evaporator. A colourless oil was produced.

[0245] NMR spectra were recorded with a Varian Unityplus-400 spectrometer. All NMR experiments were conducted at 25 °C.NMR spectra were referenced to the residual peak of the solvent used, e.g., chloroform at 7.26 ppm. Spectra were recorded with between 16 and 128 transients. An initial pulse (calibrated to 180°) was followed by an incremental delay of 1.25 ms and a 90° observational pulse.

[0246] UV-Vis spectra were recorded with an Agilent Technologies Cary 50 UV- Visible Spectrophotometer. Spectra were recorded at medium pace from 300 nm to 900 nm. 3.5 mL quartz cuvettes were used with optical pathways of 10 mm. All samples were referenced to a baseline.

[0247] GCMS testing was conducted with a Shimadzu QP 2010 Ultra fitted with an SGE SolGel Wax column. (1.0 pL film, I.D. 0.25 mm, 30 m). All GCMS runs were started with an initial temperature of 40 °C, held for 1 minute. Then temperature was ramped to 100 °C at 20 °C / min, held for 3 min. Then temperature was ramped to 190 °C at 30 °C / min, held for 9 min. Injection port temperature was set at 100 °C to prevent any thermal breakdown of cyclic peroxides. The mass-spec interface was set at 200 °C. Column flow of He gas was linear at 2 mL / min. Split ratio was set at 100 to 1. Chloroform was used as the solvent for all GCMS testing.

[0248] To track the progression of potential degradation reactions, TPTP at 20 mM in CDCL was prepared. NMR tubes with various amounts of catalyst were prepared andaliquots of 0.5 mL 20 mM TPTP solution was added.1H NMR spectra were collected at various time intervals.

[0249] To track the breakdown of TPTP with GCMS, a 2 mL solution was made in deacidified chloroform to concentrations of; 20 mM TPTP, 4 mM Bi(OTf)s, and 4M aromatic aldehyde. Aliquots of 0.1 mL were taken from the 2 mL reaction at various times throughout reaction progression. As Bi(OTf)3 has low solubility in chloroform, the aliquots were passed over 1 g of a solid filter of alumina in a pipette to remove any catalyst. This is crucial to prevent further catalytic breakdown in the injection port. The aliquots were pushed through with 1 mL of deacidified chloroform into GCMS vials and analysed in accordance with GCMS procedure outlined herein.

[0250] ABTS assays were conducted with TPTP:ABTS:HRP at 100:300: 1 mol. ratio such that TPTP molarity reflects the initial concentration prior to any potential degradation. When any catalysts were used, they were at mol. ratio TPTP:Catalyst at 10: 1. Solutions of ABTS and HRP must be prepared on the same day of testing and kept refrigerated where possible to avoid oxidation of ABTS and degradation of HRP.

[0251] During prolonged storage under aerobic conditions and exposure to UV light, chloroform can be converted to phosgene and hydrochloric acid. As there are known TATP and TPTP breakdown mechanisms with hydrochloric acid such, using acidified chloroform as a solvent for any degradation testing may be misleading. To deacidify the chloroform, it was passed through a column of activated alumina. To be confident of complete deacidification, chloroform used during deacidification testing was passed through an equal mass of alumina. Once deacidified, chloroform was stored in UV resistant containers under activated molecular sieves to aid in drying the solvent.

[0252] Differential Scanning Calorimetry (DSC) data was recorded with a Netzsc DSC 204 Fl Phoenix and accurate mass values were recorded with a Netzsc Sta 449 F3 Jupiter simultaneous thermal analyser able to record mass accurate to ±0.1 pg. Issues with calibration and sensitivity meant that it was most consistent to use this scale to record mass to ±0.01 mg.

[0253] To track the heat production of reactions, DSC was used to measure the heat produced over time. To do this, isothermal runs were performed at 25 °C in 40 pL aluminium crucibles. 15 pL of aromatic aldehyde was used to act as the solvent. TPTP was measured in values between 1 and 3 mg. Various amounts of catalyst and TPTP were used, averaging 1:5 mol ratio of Catalyst:TPTP. To calculate the heat of reaction, the integral of a mW / mg vs time graph was taken to calculate J / g of the reaction in reference to TPTP.

[0254] GCMS testing with TATP could not be performed in the UNSW Canberra laboratories due to risk assessment requirements of working with TATP. Testing was instead conducted at Defence Science Technology (DST) Edinburgh, South Australia, and instructed via distance.

[0255] Thus, 0.8 mL of 50 mM TATP solution in acetonitrile (MeCN), 0.8 mL of 1000 mM p-anisaldehyde in MeCN and 5.25 mg of Bi(OTf)s were added to 0.4 mL of MeCN in a 5 mL round bottom flask. The flask was stoppered and stirred at room temperature. 0.1 mL aliquots were removed at 0, 2, 5, 10, 15, 20, 25, and 30 minutes. These aliquots were washed with 1 mL of Milli-Q water and extracted with 0.9 mL of hexane. The hexane extract was analysed by GCMS. For a control test, this method was also conducted with no Bi(OTf)s catalyst.Industrial Applicability

[0256] The industrial applicability of the disclosed technology is apparent from the following use scenario: A potential explosive is reported to explosive ordnance disposal first responders. It is determined that this explosive is likely an organic peroxide. It is deemed unacceptable to blow-in-place. Through an appropriate mechanism of delivery as to prevent physical disruption, e.g., a fine mist spray, the explosive is wetted with p-anisaldehyde as much as practical or until fully dissolved. Explosive ordnance disposal responders have a guide for the amount of the reagent required to degrade the specific amount of explosive. Then, a concentrated solution of Bi(OTf)s in p-anisaldehyde is sprayed onto the bulk liquid. This is left for a known upper bound of degradation time. The solution is now safe. The solution can then be removed through soaking in absorbent pads or scraping into a container. This can then be transported away without risk of detonation. If required, the solution can be used for forensic analysis, with the products of the reaction mechanism presenting a characterisation of the initial explosive.

[0257] Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.Statements of Invention

[0258] The present invention is defined according to the following non-exhaustive statements of invention:

[0259] A field-relevant method for the non-explosive chemical degradation of one or more organic peroxides, the method comprising:

[0260] treating the one or more organic peroxides with one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ring-open and thereby degrade the one or more organic peroxides.

[0261] A method according to paragraphs

[0260] and

[0261] , wherein the one or more organic peroxides are selected from tripentanone triperoxide (TPTP), triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0262] A method according to paragraphs

[0260] and

[0261] or

[0262] , wherein the one or more organic peroxides are selected from triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

[0263] A method according to any one of paragraphs

[0260] to

[0263] , wherein the one or more organic peroxides comprise triacetonetriperoxide (TATP).

[0264] A method according to any one of paragraphs

[0260] to

[0264] , wherein the one or more aromatic aldehydes comprise benzaldehyde.

[0265] A method according to any one of paragraphs

[0260] to

[0265] , wherein the one or more aromatic aldehydes are selected from benzaldehydes substituted at the ortho- and / or para- positions by one or more electron-donating functional groups.

[0266] A method according to any one of paragraphs

[0260] to

[0266] , wherein the one or more electron-donating functional groups is methoxy.

[0267] A method according to any one of paragraphs

[0260] to

[0267] , wherein the one or more aromatic aldehydes are selected from o-anisaldehyde and p-anisaldehyde.

[0268] A method according to any one of paragraphs

[0260] to

[0268] , wherein the one or more aromatic aldehydes comprise p-anisaldehyde.

[0269] A method according to any one of paragraphs

[0260] to

[0269] , wherein the one or more Lewis acids are selected from metal triflates.

[0270] A method according to any one of paragraphs

[0260] to

[0270] , wherein the metal triflates are selected from post-transition metal or pnictogen metal triflates.

[0271] A method according to any one of paragraphs

[0260] to

[0271] , wherein the metal triflates are selected from Y(OTf)3, Bi(OTf)3, In(OTf)3, and Sc(OTf)3.

[0272] A method according to any one of paragraphs

[0260] to

[0272] , wherein the metal triflates are selected from Bi(OTf)3, In(OTf)3, and Sc(OTf)3.

[0273] A method according to any one of paragraphs

[0260] to

[0273] , wherein the metal triflates comprise Bi(OTf)3.

[0274] A method according to any one of paragraphs

[0260] to

[0274] , wherein the organic peroxide and the catalyst are present in a weight ratio of between about 50: 1 and about1: 1.

[0275] A method according to any one of paragraphs

[0260] to

[0275] , wherein the organic peroxide and the catalyst are present in a weight ratio of between about 30: 1 and about 2: 1.

[0276] A method according to any one of paragraphs

[0260] to

[0276] , wherein the organic peroxide and the catalyst are present in a weight ratio of between about 20: 1 and about 3: 1.

[0277] A method according to any one of paragraphs

[0260] to

[0277] , wherein the organic peroxide and the catalyst are present in a weight ratio of between about 10: 1 and about 4: 1.

[0278] A method according to any one of paragraphs

[0260] to

[0278] , wherein the organic peroxide and the catalyst are present in a weight ratio of about 5: 1.

[0279] A method according to any one of paragraphs

[0260] to

[0279] , wherein the aromatic aldehyde is provided in molar excess.

[0280] A method according to any one of paragraphs

[0260] to

[0280] , wherein the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:50 and about 1:5.

[0281] A method according to any one of paragraphs

[0260] to

[0281] , wherein the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1:25 and about 1:5.

[0282] A method according to any one of paragraphs

[0260] to

[0282] , wherein the organic peroxide and the aromatic aldehyde are present in a weight ratio of between about 1: 15 and about 1:5.

[0283] A method according to any one of paragraphs

[0260] to

[0283] , wherein the organic peroxide and the aromatic aldehyde are present in a weight ratio of about 1: 10.

[0284] A method according to any one of paragraphs

[0260] to

[0843] , wherein the one or more aromatic aldehydes comprises p-anisaldehyde, and the one or more Lewis acids comprises Bi(OTf)3.

[0285] A method according to paragraph

[0285] , wherein the p-anisaldehyde, and the Bi(OTf)3are present in a weight ratio of about 250: 1.

[0286] A method according to any one of paragraphs

[0260] to

[0286] , wherein the ringopening of the one or more peroxides is performed to substantial completion over a period of about 10 min to about 10 h.

[0287] A method according to any one of paragraphs

[0260] to

[0287] , wherein the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 30 min to about 4 h.

[0288] A method according to any one of paragraphs

[0260] to

[0288] , wherein the ringopening of the one or more peroxides is performed to substantial completion over a period of about 1 h.

[0289] A method according to any one of paragraphs

[0260] to

[0289] , wherein the method is performed under ambient conditions.

[0290] A method according to any one of paragraphs

[0260] to

[0290] , wherein the one or more aromatic aldehydes and the one or more Lewis acids are combined prior to treating the one or more organic peroxides.

[0291] A method according to any one of paragraphs

[0260] to

[0291] , wherein the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides sequentially.

[0292] A method according to paragraph

[0292] , wherein the sequential addition of the one or more aromatic aldehydes and the one or more Lewis acids to the one or more organic peroxides is performed with the one or more aromatic aldehydes added first.

[0293] A method according to paragraph

[0292] , wherein the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides by spraying, misting, deluging, or drop-wise.

[0294] A method according to any one of paragraphs

[0260] to

[0294] , further comprising an initial step of determining the presence of the one or more organic peroxides.

[0295] A method according to paragraph

[0295] , further comprising the step of determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation.

[0296] Use of one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ring-open and thereby chemically degrade one or more organic peroxides.

[0297] A kit of parts for performing a field-relevant method for the non-explosive chemical degradation of one or more organic peroxides, the kit comprising:

[0298] one or more aromatic aldehydes;

[0299] one or more Lewis acids; and

[0300] instructions for their deployment to ring-open and thereby degrade the one or more organic peroxides.

[0301] A kit according to paragraphs

[0298] to

[0301] , further comprising a means of detecting or confirming the presence of the one or more organic peroxides.

[0302] A kit according to paragraph

[0302] , further comprising a means of determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation.

[0303] A kit according to any one of paragraphs

[0298] to

[0303] , wherein the one or more aromatic aldehydes and one or more Lewis acids are present in a weight ratio of between about 1:25 and about 1:5.

[0304] A kit according to any one of paragraphs

[0298] to

[0304] , further comprising one or more mixing and / or delivery apparatus for deploying the kit.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS1. A field -relevant method for the non-explosive chemical degradation of one or more organic peroxides, the method comprising: treating the one or more organic peroxides with one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ringopen and thereby degrade the one or more organic peroxides.

2. A method according to claim 1, wherein the one or more organic peroxides are selected from tripentanone triperoxide (TPTP), triacetonetriperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methylethylketone peroxide (MEKP).

3. A method according to claim 1 or claim 2, wherein the one or more aromatic aldehydes are selected from benzaldehydes substituted at the ortho- and / or para- positions by one or more electron-donating functional groups.

4. A method according to any one of the preceding claims, wherein the one or more Lewis acids are metal triflates selected from Y(OTf)3, Bi(OTf)s, In(OTf)3, and Sc(OTf)3.

5. A method according to any one of the preceding claims, wherein the organic peroxide and the catalyst are present in a weight ratio of between about 50: 1 and about 1: 1.

6. A method according to any one of the preceding claims, wherein the organic peroxide and the catalyst are present in a weight ratio of about 5: 1.

7. A method according to any one of the preceding claims, wherein the organic peroxide and the aromatic aldehyde are present in a weight ratio of about 1: 10.

8. A method according to any one of the preceding claims, wherein the one or more aromatic aldehydes comprises p-anisaldehyde, and the one or more Lewis acids comprises Bi(OTf)3.

9. A method according to claim 8, wherein the / ^-anisaldehyde, and the BiiOTfjs are present in a weight ratio of about 250: 1.

10. A method according to any one of the preceding claims, wherein the ring-opening of the one or more peroxides is performed to substantial completion over a period of about 10 min to about 10 h.

11. A method according to any one of the preceding claims, wherein the method is performed under ambient conditions.

12. A method according to any one of the preceding claims, wherein the one or more aromatic aldehydes and the one or more Lewis acids are combined prior to treating the one or more organic peroxides; or are added to the one or more organic peroxides sequentially with the one or more aromatic aldehydes added first.

13. A method according to claim 12, wherein the one or more aromatic aldehydes and the one or more Lewis acids are added to the one or more organic peroxides by spraying, misting, deluging, or drop-wise.

14. A method according to any one of the preceding claims, further comprising an initial step of determining the presence of the one or more organic peroxides; and optionally determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation.

15. Use of one or more aromatic aldehydes in the presence of catalytic amounts of one or more Lewis acids, to ring-open and thereby chemically degrade one or more organic peroxides.

16. A kit of parts for performing a field-relevant method for the non-explosive chemical degradation of one or more organic peroxides, the kit comprising: one or more aromatic aldehydes; one or more Lewis acids; and instructions for their deployment to ring-open and thereby degrade the one or more organic peroxides.

17. A kit according to claim 16, further comprising a means of detecting or confirming the presence of the one or more organic peroxides.

18. A kit according to claim 17, further comprising a means of determining the moisture content of the one or more organic peroxides and surrounds prior to commencing degradation.

19. A kit according to any one of claims 16 to 18, wherein the one or more aromatic aldehydes and one or more Lewis acids are present in a weight ratio of between about1:25 and about 1:5.

20. A kit according to any one of claims 16 to 19, further comprising one or more mixing and / or delivery apparatus for deploying the kit.

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