Process for the nitrate formation of alpha, omega-alkanediol monoacylates

Abstract

The present invention relates to a safe and efficient process for the nitric acid ester formation of alpha, omega-C 3‑10 alkanediol monoacylates. The process is safer for the operator and allows to obtain advantageous yields on an industrial scale.

Description

[0001] This invention relates to a method for manufacturing ω-nitrooxy-C 3-10 A safe and effective method for alkyl-1-ols.

[0002] Global temperatures are rising, a process known as global warming or climate change. One of the main focuses of mitigating this warming effect is reducing the amount of greenhouse gases emitted into the atmosphere. Greenhouse gases are emitted from several different natural and anthropogenic sources; however, the two sources with the greatest impact are the agricultural industry and the fossil fuel industry. In agriculture, ruminants, particularly cattle, are major contributors to biogenic methane formation, and it is estimated that preventing methane formation by ruminants would almost stabilize atmospheric methane concentrations.

[0003] 3-Nitrooxypropanol (3-NOP, also known as 3-nitrooxy-propan-1-ol or 1,3-propanediol mononitrate) has been reported to be highly effective in reducing methane formation in ruminants without affecting microbial fermentation in a manner harmful to the host animal (WO-2012 / 084629). Furthermore, WO-2012 / 084629 discloses the preparation of 3-nitrooxypropanol by reacting 3-bromopropanol with silver nitrate in acetonitrile; however, this method is uneconomical for industrial-scale production.

[0004] For industrial-scale production of ω-nitrooxy-C 3-10 A potential pathway for alkyl-1-ols involves the direct nitrate ester formation of the corresponding α,ω-alkyldiols. However, this reaction tends to be poorly selective and results in the formation of large quantities of dinitrated alkyldiols. Furthermore, this pathway requires highly safe measures because organic nitrates and even dinitrates are explosive and therefore difficult to handle even in dilute solutions.

[0005] An alternative to the direct nitrate ester formation of α,ω-alkanediols is a three-step process involving the temporary protection of one of the two alcohol groups prior to nitrate ester formation (e.g., via acetylation), followed by nitrate ester formation and subsequent sequential removal of the respective protecting group. However, even though safety and selectivity are thus improved, the additional reaction steps typically lead to a significant loss in overall yield and a significant increase in processing costs.

[0006] Therefore, there is a ongoing need to optimize the three-step method to allow for the safe and economical production of large quantities of ω-nitrooxy-C from α,ω-alkanediols. 3-10 Alkyl-1-ols. Furthermore, post-processing strategies are needed to allow for the quantitative recovery of reactants and solvents.

[0007] Surprisingly, it has now been found that ω-nitrooxy C can be obtained in high yields using a highly specialized three-step method.3-10 Alkyl-1-ols, such as, in particular, 3-nitrooxypropanol, while maintaining reaction stability and thus ensuring method safety.

[0008] The method comprises the following sequential steps: (a) acylation of the corresponding α,ω-alkanediol with an acylation agent; (b) reaction of the obtained α,ω-C with a nitrating agent. 3-10 Nitrate ester formation of alkyldiol monoacylates to form α,ω-C 3-10 Alkanediol mononitrate monoacylates; then (c) hydrolysis of the acyl group to obtain the corresponding α,ω-C 3-10 Alkanediol mononitrate; and optionally (d) solvent post-treatment.

[0009] Individual steps (a) through (d) are new.

[0010] Therefore, in the first embodiment, the present invention relates to:

[0011] (B) Perform α,ω-C in the following manner 3-10 Continuous nitrate ester formation of alkyldiol monoacylates: This involves reacting the nitrating agent with α,ω-C... 3-10 A solution of an alkyldiol monoacylate and an inert solvent is reacted in a unit of an apparatus comprising at least two reactors in series, the reaction being carried out by simultaneously feeding the solution into a first reactor and a second reactor to obtain the corresponding α,ω-C 3-10 Alkyl diol mononitrate monoacyl derivative.

[0012] In another embodiment, the present invention relates to a method for preparing α,ω-C 3-10 A method for producing alkyl glycol mononitrate, preferably propylene glycol mononitrate, the method comprising the following steps immediately following step (B): step A before step (B), step (C) after step (B), and optional step (D), the steps being...

[0013] (A) Acylation of α,ω-alkyldiol with an acylation agent (acylation reaction), said acylation comprising reacting an α,ω-C-alkyldiol with an acylation agent. 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The step of refeeding the recycled reaction components of the alkyldiol diacylate back into the acylation reaction is conditional upon the addition of 0.5 to 1.5 moles of water per mole of recycled acylation group in the acylation reaction, and the acylation agent, α,ω-C 3-10 Alkanediol monoacylates and 2 times α,ω-C 3-10 The total (molar) sum of alkyl diol diacylates and α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C3-10 The total molar ratio of alkyl diol diacylates is selected from the α,ω-C ratio per mol. 3-10 The alkyldiol ranges from 0.5 mol to 1.1 mol, preferably from 0.6 mol to 1 mol, and most preferably from 0.75 mol to 1 mol;

[0014] (C) α,ω-C is performed in the following manner 3-10 Two-phase hydrolysis of alkyldiol mononitrate monoacylates: The reaction of a base with α,ω-C... 3-10 A solution of alkyl diol mononitrate monoacylated and an inert solvent is continuously fed into a stirred cascade reactor to obtain a product containing inert solvent and α,ω-C 3-10 A solution of alkyl diol mononitrate; and optionally,

[0015] (D) Removing and recovering the inert solvent from the solution by distillation, including removing the inert solvent and α,ω-C 3-10 The fractions of the mixture of alkyl diol mononitrates are partially condensed and continuously returned to the distillation process.

[0016] Definition of terminology

[0017] As used in this article, “α,ω-C” 3-10 "Alkanediol" refers to a straight-chain α,ω-alkanediol having 3 to 10 carbon atoms, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. In all embodiments of the invention, the most preferred α,ω-carbon diol is... 3-10 Alkanediol is 1,3-propanediol (also referred to as PD in this paper).

[0018] As used in this article, “α,ω-C” 3-10 "Alkanediol monoacylates" refer to straight-chain α,ω-alkanediols as defined above, wherein one of the hydroxyl groups has been esterified. Preferably, the acyl moiety is a straight-chain or branched C14 group. 1-6 Acyl group, more preferably straight-chain or branched C 1-4 Acyl groups, such as most preferably acetyl groups (-C(=O)-CH3). In all embodiments of the invention, 1,3-propanediol monoacylates are particularly preferred. In all embodiments of the invention, α,ω-C... 3-10 The alkyldiol monoacetate is 1,3-propanediol monoacetate (also referred to as PDMA in this paper).

[0019] As used in this article, “α,ω-C” 3-10"Alkanediol diacidate" refers to a straight-chain α,ω-alkanediol as defined above, wherein both hydroxyl groups have been esterified. In all embodiments of the invention, 1,3-propanediol diacidates are particularly preferred. In all embodiments of the invention, the most preferred α,ω-C 3-10 The alkyldiol diacetate is 1,3-propanediol diacetate (also referred to as PDDA in this paper).

[0020] As used in this article, “α,ω-C” 3-10 "Alkanediol mononitrate" refers to a straight-chain α,ω-alkanediol as defined above, wherein one of the hydroxyl groups has been nitrated, such as 3-nitrooxypropane-1-ol (also known as 3-nitrooxypropanol or 3-hydroxypropyl-1-nitrate), 4-nitrooxybutane-1-ol, 5-nitrooxypentane-1-ol, 6-nitrooxyhexane-1-ol, 7-nitrooxyheptane-1-ol, 8-nitrooxyoctane-1-ol, 9-nitrooxynonane-1-ol, and 10-nitrooxydecane-1-ol. In all embodiments of the invention, 3-nitrooxypropane-1-ol (also known herein as propanediol mononitrate or PDMN) is particularly preferred.

[0021] As used in this article, “α,ω-C” 3-10 "Alkanediol mononitrate monoacylates" refers to α,ω-C as defined above. 3-10 Alkanediol monoacylates, wherein the remaining hydroxyl groups have been nitrated. In all embodiments of the invention, 1,3-propanediol mononitrate monoacylates are particularly preferred. In all embodiments of the invention, α,ω-C... 3-10 The alkyldiol mononitrate monoacetate is 1,3-propanediol mononitrate monoacetate (also referred to as PDMNMA in this paper).

[0022] As used herein, the term "α,ω-alkyldiol dinitrate" refers to a straight-chain α,ω-alkyldiol as defined above, wherein both hydroxyl groups have been nitrated, such as 1,3-propanediol dinitrate, 1,4-butanediol dinitrate, 1,5-pentanediol dinitrate, 1,6-hexanediol dinitrate, 1,7-heptanediol dinitrate, 1,8-octanediol dinitrate, 1,9-nonanediol dinitrate, and 1,10-decanediol dinitrate. In all embodiments of the invention, 1,3-propanediol dinitrate (also referred to herein as PDDN) is particularly preferred.

[0023] As used herein, the term "inert solvent" (also abbreviated as "S") is understood to mean a solvent that does not participate in the chemical reaction in the reaction medium and under the operating conditions, and is inert to both reactants and products. In a preferred embodiment, the inert solvent is a halogenated solvent. The term "halogenated solvent" means a solvent containing one or more halogen atoms, and refers to any solvent selected from, but not limited to, dichloromethane, diiodomethane, carbon tetrachloride, dichloroethane, or chloroform. Most preferably, in all embodiments of the invention, the inert solvent is dichloromethane (also referred to herein as DCM).

[0024] As used in this invention, the term "consistently composed of" means that no other components have been intentionally added besides the listed components / ingredients / solvents, etc. However, the possibility of trace impurities introduced by the corresponding raw materials cannot be excluded.

[0025] Nitrate formation

[0026] This invention relates to the preparation of α,ω-C 3-10 A continuous nitrate ester formation process for alkyldiol mononitrate monoacylates, the process comprising, in a set of components of an apparatus comprising at least two reactors in series, reacting a nitrating agent with a mixture containing the corresponding α,ω-C 3-10 The reaction of a solution of an alkyldiol monoacylate and an inert solvent (hereinafter also referred to as (BI)) is characterized by the simultaneous feeding of said solution into a first reactor (also referred to as reactor B1) and a second reactor (also referred to as reactor B2) (see See Figure 2 ).

[0027] Preferably, the nitrate ester formation is carried out continuously in a flow reactor, such as, for example, in... Figure 2 As depicted in the text.

[0028] A flow reactor according to the invention is a device in which a chemical reaction occurs in a channel or pipe. Flow reactors are typically continuously operated (as opposed to batch reactors) and have channels / pipes in which the reaction occurs (e.g., Figure 2 Reactors B1 and B2 in the reactors are used. Reaction stoichiometry is defined by the concentrations of the reagents and their flow rate ratios. The (average) residence time is given by the ratio of the reactor volume to the total flow rate. The flow reactor preferably includes (static) mixing elements, such as SMX mixers or Kenics mixers.

[0029] As used herein, the term "residence time" refers to the volume of the reaction zone divided by the outlet volumetric flow rate of the reactants at the temperature and pressure of the reaction system. In one specific embodiment of the invention, the average residence time is calculated using the density at the corresponding outlet temperature of the reactor.

[0030] Preferably, the mass flow rate of the solution (BI) entering the first reactor is selected from the range of 40% to 60% of the total mass flow rate of the solution (BI), and the remainder is fed into the second reactor.

[0031] As used herein, the terms "mass flow rate" or "mass flow rate" can include not only actual or measured mass flow rates but also calculated mass flow rates. It typically refers to the mass flow rate of the reaction solution, as measured in the corresponding feed line. This mass flow rate can be calculated or measured using a suitable sensor located in the corresponding feed line.

[0032] In a particularly advantageous embodiment, the continuous nitrate ester formation according to the invention comprises the following continuous steps:

[0033] (N-1) Provides a continuously operating flow reactor comprising at least two reactors in series, reactor (1) (also referred to herein as B1) and reactor (2) (also referred to herein as B2).

[0034] (N-2) provides α,ω-C 3-10 Solutions of alkyl diol monoacylates and inert solvents (i.e., BI), and

[0035] (N-3) Nitrifying agent and a first portion of the solution are fed into reactor (1), and then (N-4) a second portion of the solution is added to reactor (2).

[0036] The prerequisite is that the mass flow rate of the solution entering reactor 1 is selected from 40% to 60% of the total mass flow rate of the solution, while the remaining solution is fed into reactor 2.

[0037] As used herein, the term "nitrating agent" (also referred to herein as NA) means a compound that, when reacted with a reactant substrate, forms a compound having a nitrate ester (-O-NO2) group. Exemplary nitrating agents include, but are not limited to, nitric acid and nitrates, such as alkali metal nitrates, such as KNO3, and nitrosulfuric acid (i.e., a mixture of nitric acid and sulfuric acid).

[0038] In all embodiments of the present invention, the nitrifying agent is preferably nitric acid applied as nitrosulfuric acid, i.e., a mixture of nitric acid and sulfuric acid.

[0039] In the continuous nitrate ester formation according to the invention, based on HNO3, it is preferred to use 1.5 mol to 2.5 mol equivalents, more preferably 1.7 mol to 2.3 mol equivalents, and most preferably 1.9 mol to 2.0 mol equivalents of H2SO4.

[0040] In the continuous nitrate ester formation according to the present invention, based on α,ω-C 3-10 Alkyl glycol monoacylates are preferred, with an amount of 1 to 1.5 mol equivalents, and more preferably 1.1 to 1.2 mol equivalents of HNO3.

[0041] In the continuous nitrate ester formation according to the present invention, it is further preferred that the reaction volumes of reactor (1) and reactor (2) are selected from 4:1 to 1:4, preferably 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0042] Continuous nitrate ester formation is preferably carried out in two reactors (i.e., reactor (1) and reactor (2)). Figure 2 The average dwell time (in B1 and B2) ranges from about 5 seconds to about 30 seconds, preferably from about 10 seconds to about 20 seconds, and most preferably from about 15 seconds to 19 seconds.

[0043] Preferably, in all embodiments of continuous nitrate ester formation, the solution (i.e., BI) is substantially composed of α,ω-C 3-10 Composed of alkyl diol monoacylate and inert solvent.

[0044] As used in this invention, the term "consistently composed of" means that no other components have been intentionally added besides the listed components / ingredients / solvents. However, the possibility of trace impurities introduced by the respective raw materials is not excluded.

[0045] Even more preferably, α,ω-C in an inert solvent 3-10 The concentration of the alkyldiol monoacylate is selected from 10% to 60% by weight, more preferably 20% to 50% by weight, and most preferably 35% to 45% by weight, with the remainder being an inert solvent.

[0046] In a particularly advantageous embodiment, the continuous nitrate ester formation according to the invention further comprises the following steps:

[0047] (N-5a) Optionally, in the presence of a base, the reaction mixture (in B3) is quenched with water (also referred to herein as NRM), thereby producing a two-phase mixture consisting of an organic phase and an aqueous phase (also referred to herein as NBM).

[0048] (N-5b) The two-phase mixture (NBM) is subjected to phase separation (in B4) to obtain an organic phase (also referred to herein as NOP) and an aqueous phase (also referred to herein as NAP).

[0049] (N-5c) Optionally, the aqueous phase from phase separation (NAP) is concentrated to recover H2SO4, provided that no alkali is used for neutralization, and

[0050] (N-5d) Optionally wash the organic phase (NOP) obtained in (N-5c) with water at least once and / or dry the organic phase.

[0051] Figure 2 The present invention outlines a particularly preferred continuous nitrate ester formation comprising the consecutive steps (N-1), (N-2), (N-3), (N-4), (N-5a), (N-5b) and (N-5c).

[0052] It should be understood that the continuous nitrate ester formation according to the invention may also include, for example, separating / concentrating α,ω-C from the organic phase (NOP) by (partial) distillation of the solvent. 3-10 The steps for alkyl diol mononitrate monoacylates.

[0053] In all embodiments of the invention, the nitrate forming reaction mixture (NRM) preferably consists substantially of residual / unreacted nitrating agent, α,ω-C 3-10 Alkanediol mononitrate ester, unreacted α,ω-C 3-10 Composed of alkyl diol monoacylate and inert solvent.

[0054] Suitable bases include, but are not limited to, alkali metal or alkaline earth metal bases, such as alkali metal or alkaline earth metal basic hydroxides or carbonates, as well as ammonia and amines. The base is preferably selected from NaOH (caustic soda), KOH, Ca(OH)₂, or ammonia, and more preferably, aqueous solutions thereof. Most preferably, in all embodiments of the invention, the base is an aqueous solution of NaOH (caustic soda).

[0055] In the continuous nitrate ester formation according to the invention, it is preferable not to use alkali for quenching.

[0056] Therefore, in another particularly advantageous embodiment, the quenching of the nitrate-forming reaction mixture (NRM) is performed with cold water, for example, with water in the temperature range of 0°C to 20°C, more preferably 5°C to 15°C.

[0057] In the continuous nitrate ester formation according to the invention, advantageously, the outlet reaction temperature of reactor (1) is equal to or lower than 40°C, preferably 30°C, more preferably 20°C, even more preferably 10°C, and most preferably equal to or lower than 5°C. The outlet reaction temperature of reactor (2) can be slightly higher. However, preferably, the outlet temperature of reactor (2) is selected to be in the range of 15°C to 25°C.

[0058] Advantageously, in all embodiments, the reaction temperature of the quenching step (N-6a) is equal to or lower than 20°C, preferably equal to or lower than 15°C, and more preferably equal to or lower than 10°C.

[0059] acylation

[0060] In a preferred embodiment, the method according to the invention further includes a step (A) prior to step (B), which involves acylation of α,ω-alkanediol with an acylation agent (acylation reaction), the acylation including the step of refeeding recycled reaction components into the acylation reaction as outlined above.

[0061] It should be understood that acylation may further include isolating and / or purifying the α,ω-C obtained by the methods disclosed herein or any other suitable method in the art. 3-10 Steps for alkyl diol monoacylates.

[0062] It should be understood that, as used herein, the term "reaction component" refers to the acylation reaction component that participates in the acylation reaction, namely, α,ω-alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 Alkyl diol diacylate, acylating agent, and water, but excluding any solvents or other inert components or additives.

[0063] In all embodiments of the present invention, the term "recycled reaction components" (also abbreviated as RRC) refers to unreacted α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 Alkyl diol diacylates, as well as water and acylating agents.

[0064] Furthermore, it should be understood that the recycled reaction components can be separated individually or as any mixture thereof, and therefore can be refeed individually or as any mixture thereof. Preferably, the recycled reaction components consist essentially of the following substances

[0065] (1)α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 A mixture of alkyl diol diacylates (RCC-(I))

[0066] (2) Unreacted α,ω-C 3-10 Alkanediol (RCC-(II)) and

[0067] (3) A mixture of water and acylating agent (RCC-(III)).

[0068] In all embodiments of the invention, it is preferred that at least the recycled reaction components RCC-(I) and RCC-(II) are blended before being reintroduced into the acylation reaction (see [reference]). Figure 1 ).

[0069] The acylation according to the invention can be carried out in batches or continuously.

[0070] Preferably, the acylation of α,ω-alkanediol with the acylating agent according to the invention is carried out in a reactor in which the recycled reaction components are (continuously) re-fed.

[0071] Suitable reactors include any type of vessel, such as stirred tank reactors, cascade reactors, circulating reactors, tubular reactors, but are not limited to these.

[0072] In one specific embodiment, the acylation according to the invention further comprises obtaining α,ω-C by distillation separation. 3-10 The step of producing alkyl diol monoacylates preferably involves:

[0073] ·Based on α,ω-C 3-10 Alkanediol monoacylates, α,ω-C 3-10 α,ω-C in alkyl diol monoacylates 3-10 The amount of alkyldiol is less than 0.5% by weight, preferably less than 0.1% by weight, and

[0074] ·Based on α,ω-C 3-10 Alkanediol monoacylates, α,ω-C 3-10 α,ω-C in alkyl diol monoacylates 3-10 The amount of the alkyldiol diacylate is less than 5% by weight, preferably less than 2.5% by weight.

[0075] More preferably, during the separation process, the reaction components to be recycled are collected.

[0076] Preferably, in all embodiments of the present invention, α,ω-C 3-10 The acylation and continuous separation of alkyldiol monoacylates are (entirely) continuous processes carried out in, for example, container cascade units or cascade reactors outlined in Figure (1).

[0077] A container cascade apparatus (also known as a reactor cascade apparatus) for the purposes of this invention is an apparatus comprising at least two consecutive containers in which a reaction can be performed and in which each step can only be performed after the preceding step. The containers / reactors can be of the same or different types. Those skilled in the art will understand that a container cascade apparatus can include equipment for separation and / or distillation.

[0078] The cascade reactor for the purposes of this invention is an apparatus comprising an outer reactor shell having at least one inlet at one end and at least one outlet at the opposite end; optional additional outlets for removing steam and / or byproducts; and optional ports for monitoring, sampling, and / or mixing. Within the reactor, a series of two or more segmented reaction chambers (corresponding to at least two consecutive vessels) may be defined by baffles, in which reactions can be carried out and each chamber / baffle can only be flowed through after the preceding chamber / baffle. The reactor is preferably suitable for a variety of different chemical reactions and does not need to be customized for a specific reaction. The cascade reactor can be, for example, a flow reactor.

[0079] In one specific embodiment of the invention, acylation (including the obtained α,ω-C) 3-10 The subsequent separation of alkyl diol monoacylates is a process that includes the following steps:

[0080] (A-1) Acylation of α,ω-C with an acylation agent in the initial container 3-10 Alkanediol (acylation reaction), provided that in the acylation reaction, 0.5 to 1.5 moles of water are present per mole of recycled acylated group, and that the acylating agent, α,ω-C 3-10 Alkanediol monoacylates and 2 times α,ω-C 3-10 The total (molar) sum of alkyl diol diacylates and α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The total molar ratio of alkyl diol diacylates is selected from α,ω-C per mol. 3-10 Alkanediol (also known as acetylation reaction mixture or ARM) in the range of 0.5 mol to 1.1 mol,

[0081] (A-2) Remove the acylating agent and water to form a compound containing unreacted α,ω-C 3-10 Alkanediols and monoacylated and diacylated α,ω-C 3-10 A mixture of alkyl diols (also known as AM-I),

[0082] (A-3) Separation of α,ω-C from the mixture (i.e., from AM-I) by distillation 3-10 Alkanediol monoacylates, resulting in α,ω-C 3-10 Alkanediol monoacylates contain less than 0.5% by weight of α,ω-C 3-10 Alkanediols and less than 5% by weight of α,ω-C 3-10 Alkyl diol diacyl compounds,

[0083] (A-4) Collect the reaction components to be recycled, and

[0084] (A-5) will contain at least α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The recycled reaction components of the alkyldiol diacylate are fed back into the initial container.

[0085] In all embodiments of the invention, it is preferred to occur within the acylation reaction, particularly in step (A-1).

[0086] The presence of acylated groups per mole of recycled material is preferably 0.75 mol to 1.25 mol, most preferably 0.85 mol to 1.1 mol, for example, particularly 0.95 mol to 1.05 mol of water, and

[0087] Acylating agents, α,ω-C 3-10 Alkanediol monoacylates and 2 times α,ω-C 3-10 The total (molar) sum of alkyl diol diacylates and α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The molar ratio of the total alkyl diol diacylates is preferably selected from the range of 0.6 mol to 1 mol, most preferably from the range of 0.7 mol to 1 mol, and especially particularly from the range of 0.75 mol to 1 mol.

[0088] As used herein, the term "per mole of acylate group" refers to the group derived from α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The sum of the acylation groups of alkyl diol diacylates (i.e., for each α,ω-C) 3-10 The alkyldiol monoacylate is 1 mol, and for each α,ω-C 3-10 (The amount of alkyl diol diacylate is 2 mol).

[0089] As outlined above, the reactants to be recycled in step (A-5) are essentially composed of α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The composition is alkyl diol diacylated. However, the present invention does not preclude the possibility that the acylating agent and / or water removed in step (A-2) may be recycled and re-fed when deemed appropriate.

[0090] Furthermore, it should be understood that, in order to adjust the ratios and amounts as defined herein, fresh α,ω-C may be added as needed. 3-10 Alkyl glycol, water, and / or acylating agent.

[0091] Suitable acylating agents (also referred to herein as AA) for the acylation method according to the invention are carboxylic acids and their derivatives, such as their corresponding esters and acyl halides. Preferably, the acylating agent is selected from the group consisting of: linear or branched C... 1-6 Alkyl acids, their esters or acyl chlorides, more preferably selected from straight-chain C 1-4 Carboxylic acids, such as acetic acid, propionic acid, butyric acid, and valeric acid, are used. Acetic acid is the most preferred acylation agent. Any acetic acid, i.e., its aqueous solution, can be used in all embodiments of acylation. However, it should be understood that the water content must be adjusted accordingly to meet the requirements of this invention.

[0092] The reaction temperature for the acylation reaction is preferably selected from the range of 80°C to 200°C, more preferably from 100°C to 160°C, and most preferably from 120°C to 150°C. It should be understood that the pressure must ultimately be adjusted according to the desired reaction temperature.

[0093] The reaction time for the acylation reaction (especially in step (A-1)) is preferably selected from the range of 1 hour to 10 hours, preferably from 2 hours to 8 hours, and most preferably from 3 hours to 6 hours.

[0094] The removal of the acylating agent and reaction water in step (A-2) is preferably performed by vacuum distillation and heating, which can be readily adjusted by those skilled in the art. Suitable pressures include absolute pressures from 40 mbar to 120 mbar.

[0095] Separation of α,ω-C from the reaction mixture (i.e., from AM-I) 3-10 Alkyl diol monoacylates are preferably configured such that the α,ω-C 3-10 The amount of the alkyldiol diacylate is less than 4% by weight, more preferably less than 3% by weight, most preferably less than 2.5% by weight, for example less than 1% by weight, and wherein the corresponding α,ω-C 3-10 The amount of alkyldiol is less than 0.4% by weight, more preferably less than 0.25% by weight, most preferably less than 0.2% by weight, for example, particularly less than 0.1% by weight (all amounts are based on α,ω-C). 3-10 (Amount of alkyl diol monoacylate).

[0096] In the separated (distilled) α,ω-C 3-10 Residual α,ω-C in alkyl diol monoacylates 3-10 Alkanediol diacylates and α,ω-C 3-10 The amount of alkyldiol is usually determined by GC chromatography using an FID detector.

[0097] In a particularly advantageous implementation, α,ω-C 3-10 The separation / purification of alkyldiol monoacylates (i.e., step (A-3)) is performed in two consecutive steps, namely

[0098] Step (A-3') consists of the following: distilling off most of the α,ω-C from the mixture (AM-I) obtained in step (A-2). 3-10 Alkanediol diacylates, until a mixture (AM-Ia) is obtained, which is essentially composed of α,ω-C 3-10 Alkanediols and α,ω-C 3-10 The composition of alkyl diol monoacyl compounds, followed by

[0099] Step (A-3``) consists of the following: distilling off α,ω-C from the mixture (AM-Ia). 3-10 Alkanediol monoacylates, which make distilled α,ω-C 3-10 α,ω-C in alkyl diol monoacetate 3-10 The amount of alkyldiol is as defined herein, and preferably unreacted α,ω-C is recovered. 3-10 Alkanediol.

[0100] The terms present in step (A-3`) do not preclude a small amount of α,ω-C. 3-10 The presence of alkyldiol diacetate, however, the α,ω-C 3-10 The amount of alkyldiol diacetate must be controlled to ensure that α,ω-C 3-10 α,ω-C in alkyl diol monoacetate 3-10 The final amount of alkyldiol diacetate is as defined herein. However, preferably, the amount does not exceed 3 mol%.

[0101] Even more preferably, steps (A-3`) and (A-3``) are performed in two different containers (distillation apparatus).

[0102] In an even more preferred embodiment, steps (A-3`) and (A-3``) are performed using two separate distillation columns.

[0103] In one specific embodiment, the mixture (AM-I) consists essentially of 40 mol% to 60 mol% α,ω-C 3-10 Alkanediol, 30 mol% to 50 mol% α,ω-C 3-10 Alkanediol monoacylates and 5-15 mol% α,ω-C 3-10 Composition of alkyldiol diacylate.

[0104] In another specific embodiment, the mixture (AM-Ia) consists essentially of 50 mol% to 70 mol% α,ω-C3-10 Alkanediol and 30 mol% to 50 mol% α,ω-C 3-10 Alkanediol monoacylates and up to 3 mol% α,ω-C 3-10 Composition of alkyldiol diacylate.

[0105] The reaction components to be recycled, i.e., those refeeded into the acylation reaction, particularly those fed into step (A-1) above, typically consist of the distillate from step (A-3') and the bottoms of step (A-3''), the distillate from step (A-3'') being essentially composed of α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10 The column bottoms distillate consists primarily of unreacted α,ω-C alkyl diol diacylates. 3-10 Composition of alkyldiol diacylate.

[0106] Preferably, the distillate from step (A-3') consists essentially of 10% to 40% by weight α,ω-C 3-10 Alkanediol monoacylates and 60% to 90% α,ω-C 3-10 Alkanediol diacylates and up to 5% by weight of α,ω-C 3-10 Alkyl diol composition.

[0107] Preferably, the bottom distillate of step (A-3) consists substantially of greater than 95% by weight, more preferably greater than 97% by weight, and most preferably greater than 99% by weight of α,ω-C 3-10 Alkyl diol composition.

[0108] The α,ω-C obtained in step (A-3) 3-10 The alkyldiol monoacylate preferably exhibits a purity of greater than 95% by weight, more preferably greater than 97% by weight, and most preferably greater than 98.5% by weight, as determined by GC analysis using an FID detector.

[0109] In a particularly advantageous embodiment of the invention, acylation (including the obtained α,ω-C) 3-10 The subsequent separation of alkyl diol monoacylates is as follows: Figure 1 The method, the method comprising the following steps:

[0110] (A-0) provides container cascading equipment.

[0111] (A-1') Acylation of α,ω-C with all the definitions and preferred acylation agents as given herein 3-10 Alkanediol, the acylation being performed by loading α,ω-C into a first container (V1). 3-10The reaction proceeds with the addition of alkyldiol, acylating agent, and recycled reaction components to form a reaction mixture (ARM), after which...

[0112] (A-2') The reaction mixture (ARM) is fed into the first distillation column (V2) and the acylation agent and water are distilled off to form a mixture consisting primarily of unreacted α,ω-C 3-10 Alkanediols and monoacylated and diacylated α,ω-C 3-10 The mixture (AM-I) was composed of, and then

[0113] (A-3') The mixture (AM-I) is fed into the second distillation column (V3) and the α,ω-C is distilled off. 3-10 A mixture of alkyl diol monoacylates and diacylates (i.e., RRC-(I)) to form a compound essentially composed of α,ω-C 3-10 Alkanediols and α,ω-C 3-10 A mixture of alkyl diol monoacetates (AM-Ia),

[0114] (A-3”) The mixture (AM-Ia) is fed into the third distillation column (V4) and the α,ω-C is distilled off. 3-10 Alkanediol monoacylates, which make distilled α,ω-C 3-10 α,ω-C in alkyl diol monoacetate 3-10 The amount of alkyldiol is less than 0.1% by weight, and α,ω-C is recovered simultaneously from the bottom distillate (i.e., RCC-(II)). 3-10 Alkanediol,

[0115] (A-4') Collect and optionally mix the reaction components to be recycled, and

[0116] (A-5') The optional blended recycled reaction components RRC-(I) and RRC-(II) from steps (iv) and (v) are reintroduced into the first reaction vessel (V1).

[0117] The prerequisite is in the first reactor

[0118] (a) Each mole of recycled acylate group is present in an amount of 0.5 moles to 1.5 moles, preferably 0.75 moles to 1.25 moles, most preferably 0.85 moles to 1.1 moles, for example, particularly 0.95 moles to 1.05 moles of water, and

[0119] (b) Acylating agents, α,ω-C 3-10 Alkanediol monoacylates and 2 times α,ω-C 3-10 The total (molar) sum of alkyl diol diacylates and α,ω-C 3-10 Alkanediol, α,ω-C 3-10 Alkanediol monoacylates and α,ω-C 3-10The total molar ratio of alkyl diol diacylates was adjusted to be such that, per mol of α,ω-C 3-10 The alkyldiol is in the range of 0.5 mol to 1.1 mol, preferably in the range of 0.6 mol to 1 mol, more preferably in the range of 0.7 mol to 1 mol, for example in the range of 0.75 mol to 1 mol.

[0120] It should be understood that the recycled reaction component (I) may contain, for example, up to 45% by weight of α,ω-C 3-10 Alkyl glycol monoacylates, as determined by, for example, GC analysis using an FID detector.

[0121] Preferably, in all embodiments, the recycled reaction component (II) consists of more than 90% by weight of α,ω-C 3-10 Alkanediol, more preferably greater than 95% by weight, most preferably greater than 98% by weight of α,ω-C 3-10 Alkyl glycol composition, as determined by, for example, GC analysis using an FID detector.

[0122] Of course, it should be understood that all the definitions and preferred embodiments of acylation (including acylation reactions and separation) herein also apply to methods including steps (A-1) to (A-5) and (A-0) to (A-5').

[0123] hydrolysis

[0124] In a preferred embodiment, the method according to the invention further includes a step (C) following step (B), said step (C) relating to α,ω-C 3-10 Alkanediol mononitrate monoacylates (to the corresponding α,ω-C) 3-10 A two-phase hydrolysis process of alkyldiol mononitrate, preferably 1,3-propanediol mononitrate monoacylated, to 1,3-propanediol mononitrate, said process comprising reacting a base with an α,ω-C-containing compound. 3-10 A solution of alkyl diol mononitrate monoacylated and an inert solvent, such as, in particular, dichloromethane (DCM), is continuously fed into a stirred cascade reactor.

[0125] The following text includes α,ω-C 3-10 Solutions of alkyl diol mononitrate ester monoacylates and inert solvents are also known as HS-I (e.g., in...). Figure 3 middle).

[0126] The hydrolysis process according to the present invention can be carried out in batches or continuously. Preferably, the hydrolysis process is a (completely) continuous process.

[0127] In a particularly advantageous embodiment, the hydrolysis process comprises the following sequential steps:

[0128] (H-1) provides vertical stirred cascade reactor equipment.

[0129] (H-2) will contain α,ω-C 3-10 A solution of alkyl diol mononitrate ester monoacyl, inert solvent, and alkali is continuously fed into the first (bottom) chamber. Figure 3 In the hydrolysis reactor C1),

[0130] (H-3) will contain α,ω-C 3-10 The hydrolysis reaction mixture (also referred to herein as HRM) of alkyldiol mononitrate ester, inert solvent, and residual alkaline solution is transferred to a decanter or container. Figure 3 Phase separation is performed in C2) to obtain a product containing α,ω-C 3-10 Organic solutions (I) and aqueous solutions (HS-III) of alkyl diol mononitrate esters and inert solvents (also referred to herein as HS-II), followed by

[0131] (H-4) collects α,ω-C 3-10 An organic solution (I) of alkyl diol mononitrate ester and an inert solvent (i.e., HS-II), optionally followed by

[0132] (H-5) The inert solvent is evaporated from the organic solution (I) by distillation.

[0133] Figure 3 An exemplary (and preferred) hydrolysis according to the present invention is shown.

[0134] In a preferred embodiment, the hydrolysis method according to the invention further includes an additional step (H-6), which comprises the following steps:

[0135] (H-6a) Extract the aqueous phase (HS-II) obtained in step (H-3) with an additional amount of inert solvent to recover additional α,ω-C 3-10 Alkanediol mononitrate, thereby producing an additional organic phase (II) (also referred to herein as HS-IV), and

[0136] (H-6b) The organic phase (II) is co-fed into step (H-5).

[0137] The hydrolysis process is preferably carried out (continuously) in a container cascade or cascade reactor, more preferably in a vertical stirred cascade reactor. In a preferred embodiment of the invention, the hydrolysis process is performed in a vertical stirred cascade reactor having at least 10 chambers.

[0138] For the purposes of hydrolysis processes, vertical stirred cascade reactors are both vertical reactors and stirred reactors. As used herein, the terms "vertical reactor" or "horizontal reactor vessel" refer to a reactor vessel having a substantially vertical longitudinal axis. As used herein, the term "stirred reactor" refers to a reactor having means for agitating the reactants in addition to agitation caused by flow (e.g., turbulent flow of the reactants).

[0139] In a preferred embodiment of the invention, for α,ω-C 3-10 The base for the hydrolysis reaction of alkyldiol mononitrate monoacylates is an aqueous solution of NaOH, wherein the concentration of NaOH in water is preferably selected between 1 wt% and 50 wt%, more preferably between 5 wt% and 30 wt%, and most preferably between 7.5 wt% and 15 wt%.

[0140] Advantageously, the reaction temperature of the hydrolysis reaction is selected from the range of 20°C to 70°C, preferably 30°C to 60°C, and most preferably 40°C to 60°C.

[0141] Furthermore, it is advantageous based on α,ω-C 3-10 The alkyldiol mononitrate monoacylated product is hydrolyzed using a base, preferably NaOH, in an amount of 1 mol to 1.5 mol equivalents, more preferably 1.1 mol to 1.3 mol equivalents, and most preferably 1.2 mol to 1.3 mol equivalents.

[0142] The hydrolysis reaction is preferably carried out for a reaction time ranging from about 2 hours to about 6 hours, preferably from about 3 hours to about 5 hours, and most preferably about 4 hours.

[0143] Removal and recovery of inert solvents

[0144] In a further preferred embodiment, the method according to the invention further includes a step (D) following step (C), said step (D) involving distillation from a mixture containing an inert solvent and α,ω-C 3-10 A process for removing and recovering inert solvents from mixtures of alkyldiol mononitrates, preferably 1,3-propanediol mononitrates, comprising the removal and recovery of inert solvents from a mixture containing inert solvents and α,ω-C 3-10 The liquid fraction of the mixture of alkyl diol mononitrates is partially evaporated and condensed and continuously returned to the distillation process.

[0145] Preferably, the distillation is performed in an evaporator setup, even more preferably in an evaporation setup comprising one to five evaporators, and even more preferably two to four evaporators. Figure 4 An illustrative and preferred evaporator device is shown.

[0146] The method preferably further includes separating α,ω-C, as determined, for example, by GC chromatography using an FID detector, with a purity of at least 95% by weight, preferably at least 97% by weight, and most preferably at least 98% by weight. 3-10 Alkyl glycol mononitrate.

[0147] Preferably, the separated α,ω-C 3-10 The alkyldiol mononitrate also contains less than 1% inert solvent, more preferably less than 0.5% inert solvent, and most preferably less than 0.1% inert solvent.

[0148] As used herein, the term "evaporator" refers to a device used to evaporate chemicals or mixtures of chemicals (e.g., inert solvents and α,ω-C) 3-10 A device for converting a solution of alkyl diol mononitrate (in liquid form) into its gaseous / vapor form. It should be understood that the liquid may also be partially evaporated or partially vaporized into a gaseous form, while a portion of the liquid remains liquid. The method can be used to separate mixtures, for example, by partial evaporation and partial condensation as described herein.

[0149] As used herein, the term condenser refers to a device or unit used to condense a gaseous substance or gaseous mixture into a liquid state by cooling.

[0150] In a particularly advantageous embodiment, solvent removal and recovery according to the invention comprises the following steps:

[0151] (S-1) provides an evaporator assembly including 3 evaporators.

[0152] (S-2) will contain α,ω-C in an inert solvent (also referred to herein as SI). 3-10 The solution of alkyl diol mononitrate is fed into the first evaporator. Figure 4 E1) is subjected to a pressure of 400 mbar to 600 mbar, thereby generating a gas phase (I) (also referred to herein as GP-I) and a liquid phase (I) (also referred to herein as LP-I), wherein the liquid phase (I) contains approximately 70 wt% to 95 wt% α,ω-C 3-10 Alkyl glycol mononitrate,

[0153] (S-3) The gas phase (I) is fed to the first (partial) condenser (C1) to remove the first liquid fraction (also referred to herein as LF-I) by cooling to a temperature of 20°C to 40°C, preferably to a temperature of 20°C to 35°C, more preferably to a temperature of 25-30°C, while the remaining gas phase (II) (also referred to herein as GP-II) is transferred to the second condenser (C1). Figure 4 On C2),

[0154] (S-4) Feed the liquid phase (I) (LP-I) from step (S-2) into the second evaporator. Figure 4 E2) is subjected to a pressure of 50 mbar to 150 mbar, thereby producing a gas phase (III) (also referred to herein as GP-III) and a liquid phase (II) (also referred to herein as LP-II), wherein the liquid phase (II) contains greater than 95 wt%, preferably greater than 97 wt%, most preferably greater than 98 wt% α,ω-C 3-10 Alkyl glycol mononitrate,

[0155] (S-5) Feed the gas phase (III) into the third (part) condenser. Figure 4 The second liquid phase (also referred to herein as LF-II) is removed by cooling to a temperature of 10°C to 30°C, preferably to 20°C to 30°C, more preferably to 20°C to 25°C, while the remaining gas phase (IV) (also referred to herein as GP-IV) is transferred to the fourth condenser. Figure 4 C4) to liquefy inert solvents, and

[0156] (S-6) Feed the liquid phase (II) (LP-II) from step (S-4) into the third evaporator. Figure 4 Apply a pressure of 5 to 10 millibars to E3.

[0157] The prerequisite is that at least one of LF-I and LF-II is recycled to the first evaporator or the second evaporator.

[0158] It should be understood that liquid fractions (I) and (I-) still contain α,ω-C 3-10 Alkanediol mononitrate, the α,ω-C 3-10 Alkyl glycol mononitrate is recovered through the recycled material.

[0159] Figure 4 An exemplary (and preferred) removal and recycling process according to the present invention is shown.

[0160] In the partial condensation according to the invention, the vapor stream (evaporation stream) is partially condensed (liquefied) in a condenser. The remaining (uncondensed) vapor is passed to a subsequent (total) condenser operating at a lower temperature to almost completely liquefy the remaining solvent.

[0161] Preferably, the α,ω-C in the inert solvent in step (S-2) 3-10 The amount of alkyldiol mononitrate is selected from the range of 10% to 50% by weight, more preferably from 20% to 40% by weight, wherein the α,ω-C 3-10 Alkyl diol mononitrates can be obtained, for example, from hydrolysis as described above.

[0162] Brief description of the attached figures

[0163] Figure 1 :exist Figure 1 In the embodiments described, an exemplary but non-limiting container cascade apparatus for an acylation process according to the present invention is shown:

[0164] An acylating agent (AA), α,ω-alkyldiol (AD), and water are fed into the first vessel of a vessel cascade (V1) to form a reaction mixture (ARM). The reaction mixture (ARM) is then fed into a first distillation column (V2) and the acylating agent and water are distilled off to form a mixture (AM-I). The mixture (AM-I) is then fed into a second distillation column (V3) and the "recycled reaction component (I)" consisting essentially of α,ω-alkyldiol monoacylates and α,ω-alkyldiol diacylates (ADMA and ADDA) is distilled off to form a mixture (AM-Ia). The mixture (AM-Ia) is then fed into a third distillation column (V4) and the ADMA is distilled off, while the "recycled reaction component (II)" consisting essentially of AD is recovered. During this process, the recycled reaction components (I) and (II) are continuously fed back into the first reaction vessel (V1). If necessary, small fractions (less than 5%) of the recycled reaction components (I) and (II) can be purged / removed to avoid the accumulation of potentially formed byproducts. Additionally, the acylation agent and (partially) water are reintroduced into the first reaction vessel (V1) when deemed appropriate.

[0165] Figure 2 :exist Figure 2 In an embodiment, an exemplary but non-limiting continuous-operation flow reactor apparatus for nitrate ester formation according to the present invention is shown:

[0166] Nitrifying agent and α,ω-C 3-10 A portion of a solution (BI) consisting of an alkyl diol monoacylate and an inert solvent is fed into a first reactor (B1), followed by a second portion of the solution (BI) added to a second reactor (B2). The nitrate ester-forming reaction mixture (NRM) obtained after reactor (B2) is quenched in reactor B3. The resulting two-phase mixture (NBM) is separated into two phases to obtain an organic phase (NOP) and an aqueous phase (NAP). α,ω-C 3-10 Alkyl diol mononitrate monoacyl (ADMNMA) is present in the organic phase and can be isolated therefrom.

[0167] Figure 3 :exist Figure 3In the embodiments described, an exemplary but non-limiting vertical stirred cascade reactor apparatus for the hydrolysis process according to the present invention is shown.

[0168] The first (bottom) chamber (C1) is continuously filled with substances consisting essentially of α,ω-C 3-10 Alkyl diol mononitrate monoacylates and inert solvents (HS-I) (e.g., using...) Figure 2 The solution of NOP (as described in the text) and an aqueous solution of alkali are used to form a reaction mixture (HRM). The reaction mixture (HRM) is transferred to a second vessel (C2) for phase separation, resulting in an organic phase (HS-II) and an aqueous phase (HS-III). The organic phase is then transferred to an evaporator assembly (C4) for α,ω-C... 3-10 Separation of alkyldiol mononitrate (ADMN). The aqueous phase (HS-III) is transferred to a third vessel (C3) for further extraction with an inert solvent to obtain an organic phase (HS-IV), which is then transferred (in combination with HS-II) to an evaporator assembly (C4) to recover additional ADMN.

[0169] Figure 4 :exist Figure 4 In the embodiments described, an exemplary but non-limiting evaporator apparatus for the removal and recovery of inert solvents according to the present invention is shown:

[0170] α,ω-C contained in an inert solvent (SI) 3-10 A solution of alkyldiol mononitrate is fed into the first evaporator (E1), and the first liquid fraction (LF-I) is removed from the distillate of evaporator (E1) by partial condensation in the first condenser (C1), while the remaining vapor is passed to the second condenser (C2) to liquefy the remaining inert solvent (S). The liquid phase (LP-I) from evaporator (E1) is fed into the second evaporator (E2). The second liquid fraction (LF-II) is removed from the distillate of evaporator (E2) by partial condensation in the condenser (C3), while the remaining vapor (GP-IV) is passed to the fourth condenser (C4) to liquefy the remaining inert solvent. The liquid phase (LP-II) from evaporator (E2) is fed into the third evaporator (E-3) to remove the remaining inert solvent and recover pure α,ω-C. 3-10 Alkyl glycol mononitrate. Example

[0171] A) Acylation

[0172] Acylation (equilibrium formation) is performed either batch-wise without recirculation by feeding the starting materials into a first vessel, or in a fully continuous process within a vessel cascade setup. The resulting reaction mixture from the last vessel is fed to a first distillation column to separate (remove) H₂O / HAc from PDDA / PDMA / PD. This PDDA / PDMA / PD mixture is fed to a second distillation column to remove PDDA from PD / PDMA. This PD / PDMA mixture is fed to a third distillation column to separate PDMA from PD.

[0173] Pure PDMA was obtained by distillation. The recovered PDDA, PD, and HAc were recycled and returned to the reaction vessel cascade along with a conditioning amount of water, resulting in an overall yield of 90%.

[0174] Aa) No recycled logistics (comparison)

[0175] 1,3-Propanediol (PD, 14.0 kg, 0.18 kmol, 99.7%) was mixed with acetic acid (HAc, 9.8 kg, 0.16 kmol, 100%). After inertizing the reactor with a nitrogen flow, stirring was started (500 rpm), and the jacket temperature was increased from 20 °C to 135 °C over 70 minutes and maintained at 135 °C for 4 hours under reflux of the reaction mixture. After 4 hours, the jacket temperature was set to 100 °C and the pressure was slowly reduced to approximately 100 mbar absolute while 1.55 kg of distillate was collected. 22.0 kg of residue was obtained, comprising a mixture of acetic acid, water, unreacted PD (28 wt%), 3-acetylaceton-1-ol (PDMA, 44.1 wt%), and 1,3-propanediol diacetate (PDDA, 11.3 wt%). The yield of PDMA was 44.4% based on PD, and the yield of PDDA was 8.5%.

[0176] Acetic acid / water removal was performed in a DN50 distillation column with 3.5 m BX packing, equipped with a condenser, a liquid separator for reflux regulation, and a falling film evaporator, at a feed rate of 6.7 kg / h and a reflux ratio of 0.4–0.5 under an absolute top pressure of 50 mbar. This resulted in a top product of 1.1 kg / h containing acetic acid and water, and a bottom product of 5.6 kg / h containing 34 wt% PD, 52 wt% PDMA, and 13 wt% PDDA.

[0177] PDDA removal was performed in a DN50 distillation column with 3.5 m BX packing, equipped with a condenser, a liquid separator for reflux regulation, and a falling film evaporator, at a feed rate of 1.6 kg / h and a reflux ratio of 7–8 under an absolute top pressure of 20 mbar, resulting in a top product of 0.4 kg / h containing 1 wt% PD, 40 wt% PDMA, and 54 wt% PDDA. The corresponding bottom product stream (1.2 kg / h) consisted of 44 wt% PD, 55 wt% PDMA, and 0.3 wt% PDDA.

[0178] In a DN50 distillation column with 3.5 m BX packing, equipped with a condenser, a liquid separator for reflux conditioning, and a falling film evaporator, PDMA and PD were separated at a feed rate of 1.2 kg / h and a reflux ratio of 3–4 under an absolute top pressure of 20 mbar, resulting in a top product of 0.6 kg / h containing 0.5 wt% PD, 97–98 wt% PDMA, and 1 wt% PDDA. The corresponding bottom distillate stream (0.6 kg / h) consisted of 91–92 wt% PD and 8–9% PDMA. The overall yield of PDMA was 71–73% over the three distillation steps.

[0179] Based on PD, the overall yield of PDMA (from reaction and distillation steps) is 31-33%.

[0180] Ab) Using recycled materials in a fully continuous mode (this invention)

[0181] 1,3-Propanediol (PD, 76 kg / h, 0.99 kmol / h, 99.7%) was mixed with fresh acetic acid (HAc, 57 kg / h, 100%), 89 kg / h distillate from the first distillation column (56 wt% acetic acid, 4 wt% water), 90 kg / h distillate from the second distillation column (2 wt% PD, 36.5 wt% PDMA, 61 wt% PDDA), and 110 kg / h bottoms stream from the third distillation column (97 wt% PD, 3% PDMA). The reaction was carried out in a continuous stirred tank reactor at reflux temperature (atmospheric pressure) with an average residence time of 5-6 hours to deliver a reaction mixture (a mixture of acetic acid, water, unreacted PD (29 wt%), 3-acetylaceton-1-ol (PDMA, 35 wt%) and 1,3-propanediol diacytide (PDDA, 14.5 wt%)) at a rate of 400 kg / h.

[0182] Acetic acid / water removal was performed in a DN500 distillation column with 3.7 m BX packing, equipped with a condenser, a liquid separator for reflux conditioning, and a falling film evaporator, at a feed rate of 400 kg / h and a reflux ratio of 0.5–1 under an absolute top pressure of 50 mbar. This resulted in a top product of 85 kg / h containing acetic acid and water and a bottom product of 315 kg / h containing 36 wt% PD, 45 wt% PDMA, and 19 wt% PDDA.

[0183] PDDA removal was performed in a DN1000 distillation column with 10.8 m BX packing, equipped with a condenser, a liquid separator for reflux regulation, and a falling film evaporator, at a feed rate of 315 kg / h and a reflux ratio of 10-15 under an absolute top pressure of 20 mbar. This resulted in a top product of 92 kg / h containing 2 wt% PD, 36.5 wt% PDMA, and 61 wt% PDDA. The corresponding bottom product stream (223 kg / h) consisted of 50 wt% PD, 48-49 wt% PDMA, and 1-2 wt% PDDA.

[0184] In a DN1000 distillation column with 7.5 m BX packing, equipped with a condenser, a liquid separator for reflux regulation, and a falling film evaporator, PDMA and PD were separated at a feed rate of 223 kg / h and a reflux ratio of 5–10 under an absolute top pressure of 10 mbar. This resulted in a top product of 108 kg / h containing 0.1 wt% PD, 98–99 wt% PDMA, and 1 wt% PDDA. The corresponding bottom distillate stream (115 kg / h) consisted of 98–99 wt% PD and 1–2% PDMA.

[0185] Based on (fresh) PD, the total yield of PDMA (from reaction and distillation steps) is 90%.

[0186] B) Nitrate formation

[0187] A 40% w / w solution of PDMA in dichloromethane (DCM) was reacted with nitrosulfonic acid (1.1 equivalents of HNO3, 2.2 equivalents of H2SO4, and less than 3% by weight of water) in a flow reactor at 5°C.

[0188] The nitrate ester formation reaction was carried out in a continuously operating flow reactor by mixing a DCM solution of PDMA (60 wt% DCM / 40 wt% PDMA) with nitrosulfuric acid at a constant ratio and a stable flow rate of each component. To control the reaction temperature below 40°C, the reaction was distributed via a mass flow between two flow reactors in series by feeding PDMA in two portions (reactor 1 / reactor 2 = 40% : 60%). The total residence time in the two reactors was maintained at 15–19 seconds.

[0189] Immediately after two consecutive reactor runs, the reaction was diluted / quenched with water at 10°C, followed by phase separation. The organic phase containing the intermediate 3-acyl-propion-1-nitrate (MAMN) was washed once with water to stabilize the mixture for intermediate storage in a buffer tank. The MAMN-containing organic phase can be proceeded to the next step as is, or optionally washed with water prior to the next step, with an overall yield of 99%.

[0190] The aqueous phase, which is mainly composed of dilute H2SO4, is concentrated to 65% or 96% H2SO4 for use in other applications.

[0191] C) Hydrolysis

[0192] PDMNMA (approximately 50% DCM solution) is reacted with 1,3 equivalents of NaOH (10-11% aqueous solution) at 40-56℃.

[0193] Hydrolysis of PDMNMA was performed in a vertical stirred cascade reactor by continuously feeding PDMNMA (approximately 50% DCM solution) from the bottom together with 10-11% NaOH solution (at a ratio of 1 / 1.3 equivalents). The reaction temperature was 40-56 °C, and the residence time was 4 hours. After complete conversion (>99.9%), the phases were cooled to approximately 20 °C, separated, and the aqueous phase was washed / extracted with DCM in continuous mode at room temperature (back-extraction of PDMN). The combined organic phases were post-treated by solvent removal (see D).

[0194] After removing DCM from the combined organic phase, the desired product was obtained in 97% yield.

[0195] D) Solvent removal and recovery (partial condensation)

[0196] Following hydrolysis, the organic phase is fed into a first evaporator, where a PDMN solution (containing 7-8% DCM) is generated at 500 mbar. The combined organic phase PDMN / DCM (77% DCM) is then subjected to solvent removal in a three-stage evaporator setup. The distillate (vapor stream) is directed to a partial condenser, where the liquid fraction (PDMN / DCM, approximately 55-60% PDMN) is recovered at 30°C and returned to the first evaporator. The remaining vapor is transferred to a (total) condenser operating at 0°C to recover high-purity DCM (<0.03% PDMN).

[0197] A PDMN solution (containing 7-8% DCM) from the first evaporator is fed into a second evaporator operating at 100 mbar to produce a liquid solution containing approximately 1% by weight of DCM. The distillate (vapor stream) is directed to a partial condenser, where the liquid fraction (PDMN / DCM, approximately 70-75% PDMN) is recovered at 15°C and returned to the first evaporator. The remaining vapor is transferred to a (total) condenser operating at 0°C to recover DCM (approximately 0.1% PDMN).

[0198] The PDMN solution (containing approximately 1% DCM) from the second evaporator is fed into a third evaporator operating at 10 mbar to produce a liquid solution containing less than 0.1% by weight of DCM. The distillate (vapor stream) is directed to a partial condenser, where the liquid fraction (PDMN / DCM, approximately 90% PDMN) is recovered at 0°C and returned to the first evaporator. The remaining vapor is discarded.

Claims

1. A continuous method for the formation of nitrate esters from 1,3-propanediol monoacylates, the method comprising reacting a nitrating agent with a solution containing 1,3-propanediol monoacylates and an inert solvent in components of a set of equipment, said equipment comprising at least two reactors in series, characterized in that... The solution is simultaneously fed into a first reactor and a second reactor, wherein the nitrating agent is a mixture of H₂SO₄ and HNO₃, wherein the reaction volume of the first reactor and the second reactor is selected in the range of 1:4 to 1:2, and wherein the nitrate ester formation occurs in the range of an average residence time of about 5 to about 30 seconds in the two reactors, wherein the method is used to prepare 3-nitrooxypropane-1-ol, and the method further includes the preceding step (A), wherein step (A) comprises: (A) Acylation of 1,3-propanediol with an acylation agent in an acylation reaction, said acylation comprising the step of refeeding a recycled reaction component comprising 1,3-propanediol, 1,3-propanediol monoacylate, and 1,3-propanediol diacylate back into the acylation reaction, provided that in the acylation reaction, 0.5 to 1.5 moles of water are added per mole of recycled acylation group, and the molar ratio of the total moles of the acylation agent, 1,3-propanediol monoacylate, and twice the amount of 1,3-propanediol diacylate to the total moles of 1,3-propanediol, 1,3-propanediol monoacylate, and 1,3-propanediol diacylate is selected from 0.5 mol to 1.1 mol per mole of 1,3-propanediol.

2. The method according to claim 1, wherein, The mass flow rate of the solution entering the first reactor is selected within the range of 40-60% of the total mass flow rate of the solution, and the remaining solution is added to the second reactor.

3. The method according to claim 1 or 2, wherein the concentration of the 1,3-propanediol monoacylate in the inert solvent is selected in the range of 10% by weight to 60% by weight.

4. The method according to claim 1 or 2, wherein a) The molar ratio of HNO3 to 1,3-propanediol monoacylate is selected in the range of 1 to 1.5, and b) The molar ratio of H2SO4 to HNO3 is selected in the range of 1.5 to 2.

5.

5. The method according to claim 1 or 2, wherein a) The outlet reaction temperature of the first reactor is equal to or lower than 40°C, and b) The outlet reaction temperature of the second reactor is equal to or lower than 25°C.

6. The method of claim 1, wherein step (A) is a continuous method performed in a container cascade apparatus.

7. The method of claim 1, wherein step (A) comprises the step of separating the 1,3-propanediol monoacylate, such that... a) The amount of 1,3-propanediol in the 1,3-propanediol monoacylate is less than 0.5% by weight and / or b) The amount of 1,3-propanediol diacylate in the 1,3-propanediol monoacylate is less than 5% by weight.

8. The method according to claim 1, wherein the acylating agent in step (A) is selected from carboxylic acids.

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