Production method of explosive HMX by flow synthesis

Abstract

This invention relates to a method for producing explosives by flow synthesis from the nitration of TAT. This invention relates to a method for producing HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) by flow synthesis, comprising the steps of: i. preparing an input flow mixture containing TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane), P2O5 in nitric acid, where the concentration of said nitric acid is greater than 95%, ii. feeding the input flow reagents to a flow reactor, iii. heating the reaction vessel in the flow reactor to 60°C-80°C, and recovering the reaction mixture. [Formula 1] JPEG2025509949000003.jpg52170

Description

[Technical field]

[0001] This invention relates to a process for the production of explosives from the nitration of TAT by flow synthesis, in particular to a process for the production of HMX.

[0002] Before describing the present invention in further detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the scope of the present invention will be limited only by the claims and that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0003] A first aspect of the present invention provides a process for producing HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) by flow synthesis, the process comprising the steps of: i. preparing an input flow mixture comprising TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane), excess P2O5 in nitric acid, wherein the concentration of the nitric acid is greater than 95%; ii. providing an input flow mixture to a flow reactor; iii. Heating the reaction vessel in the flow reactor to 60°C to 80°C; iv. recovering the reaction mixture; Includes.

[0004] After step iv, the reaction mixture may be cooled, such as in an ice bath, to below 10° C. to precipitate HMX. Preferably, the reaction mixture may be quenched to precipitate HMX. Quenching may be effected by mixing the reaction mixture, i.e., the output flow, and adding a quenching agent. The quenching agent may be, for example, an aqueous solution that precipitates HMX. The quenching agent may be cooled to below 10° C.

[0005] Highly preferably, the concentration of nitric acid in step i) is 99%. In another embodiment, prior to step i), I. preparing an input flow reagent A comprising TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane) dissolved in nitric acid at a concentration of greater than 95%; II. preparing an input flow reagent B containing nitric acid at a concentration greater than 95% and excess P2O5; III. Mixing and feeding input flow reagents A and B into a flow reactor; may include:

[0006] In another aspect, there is provided a method for producing HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) by flow synthesis, the method comprising: a. preparing an input flow reagent A comprising TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane) dissolved in nitric acid at a concentration greater than 95%; b. preparing an input flow reagent B comprising nitric acid having a concentration greater than 95% and excess P2O5; c. mixing and feeding input flow reagents A and B into the flow reactor; d. heating the reaction vessel in the flow reactor to 60°C to 80°C; Includes.

[0007] After steps III and d, the reaction mixture may be cooled, such as with an ice bath, to below 10° C. to precipitate HMX. Preferably, the reaction mixture may be quenched to precipitate HMX. Quenching may be effected by mixing the reaction mixture, i.e., the output flow, and adding a quenching agent. The quenching agent may be, for example, an aqueous solution that precipitates HMX. The quenching agent may be cooled to below 10° C.

[0008] Flow synthesis provides a facile means of producing approximately 100 g of HMX at R&D scale in the laboratory, and production can be easily scaled up by adding additional flow reactors without the dangers associated with forming over 100 kg of HMX explosive in a single reaction vessel. It also avoids the use of hundreds of liters of highly concentrated acid in large reaction vessels in batch reactions. Flow synthesis allows for continuous removal and safe storage of the explosive end product from the flow reactor, avoiding the accumulation of large amounts of explosive material. This allows for the production of large quantities of explosives in explosive production buildings and / or reduced safety distances, since explosive material can be transported to a safe area away from the flow reactor in the synthesis of explosive materials.

[0009] TAT may be added to the nitric acid of input flow reagent A in weight percent up to a nearly or completely saturated solution. The higher the concentration of TAT in input flow reagent A, the more efficient the reaction will be. It is highly preferred to dissolve the TAT in the nitric acid as quickly as possible before feeding it to the reaction vessel to reduce the possibility of initiating the nitration reaction.

[0010] The TAT may be dissolved in nitric acid at a concentration of 95% to 99%, with the addition of other solvents to aid in the dissolution of the hexamine.

[0011] TAT:P2O5 is in molar excess of P2O5, preferably greater than 2-fold, preferably 2-30-fold molar excess, but may be greater.

[0012] Preferably, input flow reagent A comprises only TAT and nitric acid at a concentration of 92% or less.

[0013] To facilitate achieving the desired concentration of nitric acid to initiate the nitration of TAT, the input flow reagents A and B may be premixed in a mixing tank before being fed to the flow reactor.

[0014] If input flow reagent A and input flow reagent B have only nitric acid as the acid and only nitrating agent, the total concentration of nitric acid must be sufficient for nitration to occur, for example greater than 95%.

[0015] The flow rate of input flow reagent A can be selected from appropriate flow rates together with the flow rate of input flow reagent B to provide a total concentration of nitric acid capable of nitrating hexamine (e.g., greater than 95%). The actual flow rate of input flow reagent A can be from microliters / minute to milliliters / minute to liters / minute, depending on the volume of the flow cell.

[0016] The flow rate of input flow reagent B can be selected from appropriate flow rates together with the flow rate of input flow reagent A to provide a total concentration of nitric acid capable of nitrating hexamine (e.g., greater than 95%). The actual flow rate of input flow reagent A can be from microliters / minute to milliliters / minute to liters / minute, depending on the volume of the flow cell.

[0017] Other strong acids may also be used, such as oleum.

[0018] The temperature in the flow reactor must be controlled to prevent a very exothermic reaction from occurring while at the same time providing sufficient heat to maintain the reaction. The temperature of the reactor in step iii) is between 60°C and 80°C, highly preferably between 70°C and 75°C. The temperature is controlled by a water circulator. The flow reactor may be heated and / or cooled by suitable means, e.g. a water circulator or an electric heater / cooler.

[0019] The HMX precipitate is filtered, collected, and then washed in a quenching solution, which is preferably aqueous and preferably has a pH of 7 or less.

[0020] Another aspect of the invention provides the use of flow synthesis to deliver explosives from a TAT.

[0021] Another aspect of the invention provides an apparatus for carrying out a method according to any one of the preceding claims, the apparatus being adapted to respond to explosions. [Brief description of the drawings]

[0022] [Figure 1] [Diagram 2] EXAMPLES

[0023] Experimental Reagents 99% HNO3 was purchased in 500mL quantities from Honeywell, catalog number 84392-500ML, lot number I345S. 70% HNO3 was purchased in 2.5L quantities from Fisher scientific, code number N / 2300 / PB17, lot number 1716505. Hexamine was purchased from Sigma-Aldrich in 250g quantities, catalog number 797979-250G, lot number MKCJ7669. Oleum was purchased in 500 mL quantities from Fisher, catalog number S / 9440 / PB08, lot number 1689177.

[0024] experiment Example of HMX TAT can be easily synthesized from hexamine via the intermediate DAPT, as shown in Figure 1. The main advantage of this route is that an eight-membered ring is formed, thus eliminating the possibility of RDX being formed as a by-product.

[0025] The synthesis of DAPT and TAT usually results in high yields and is non-explosive, i.e., they do not sustain an explosion, as they are explosive precursors. Therefore, these explosive precursors can be safely produced in large quantities by batch reactions, if necessary. Therefore, only the conversion of TAT to HMX needs to be done by flow chemistry, rather than the existing conventional batch reaction, to mitigate the accumulation of large amounts of explosive products.

[0026] The synthesis of DAPT is simple, and the resulting product can be easily recrystallized from acetone to produce large pure crystals. 1 1 H NMR was confirmed by comparison with the literature.

[0027] The subsequent synthesis of TAT is straightforward and can be carried out on a large scale. The product was recrystallized into a white powder by sonicating the sample in a small amount of acetone. 1 The H NMR confirmed that the spectrum contained two major peaks with an integral ratio of 12:8, corresponding to four CH3 and four CH2 protons, respectively.

[0028] As shown in Figure 2, TAT can be directly converted to HMX by nitration using a flow synthesis apparatus to control the rate of explosive production.

[0029] Experiment 1 Line A - A solution of 100 mg TAT, 1000 mg P2O5 and 2 mL 99% HNO3 was premixed as a single solution and passed through the Labtrix reactor. The preferred reaction time of 120 seconds through the flow synthesis reactor was sufficient for nitration to occur. The flow synthesis was carried out at a temperature above room temperature, and a temperature of 75°C was found to be sufficient to drive the reaction but not enough to cause an undesirable explosion. HMX was isolated without contamination by RDX.

[0030] Experiment 2 – Scaled-up Protrix reactor Line A: 2.0061 g of TAT and 20.0357 g of P2O5 were dissolved in 40 mL of 99% HNO3.

[0031] Line B was used as an emergency flush and was primed with 70% HNO3.

[0032] Line A and the Protrix reactor were primed first with 70% HNO3, followed by 99% HNO3. The reaction mixture was prepared in stages. First, P2O5 was slowly dissolved in a stirred solution of 99% HNO3. This solution was placed in an ice bath. This resulted in an opaque yellow solution. Addition of TAT to this solution reduced the opacity of the solution, but the reaction mixture remained opaque.

[0033] Line A was then primed with the reaction mixture.

[0034] [Table 1]

[0035] The solution was passed through a Protrix reactor and left overnight, whereupon crystals formed. These were isolated, washed with water, then acetone, and analyzed by NMR spectroscopy. 1 The H NMR spectrum shows the presence of multiple species in the sample, some of which correspond to unreacted TAT and partially nitrated TAT.

[0036] A highly preferred weight ratio of reactants is TAT:P2O5:HNO3 1:10:30. The nitric acid ratio may be increased to 20-60. The TAT:P2O5 is in molar excess of P2O5, preferably 5-30 fold molar excess. Nitric acid may be present in greater amounts, but it is preferred to maintain an optimum amount to reduce waste and handling of excess acid.

Claims

1. A process for producing HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) by flow synthesis, comprising the steps of: i. TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane) in nitric acid, excess P ２ O ５ preparing an input flow mixture comprising: ii. providing the input flow reagents to a flow reactor; iii. heating the reaction vessel in the flow reactor to 60° C. to 80° C.; iv. recovering the reaction mixture; The method includes:

2. 10. The method of claim 1, wherein after step iv, the reaction mixture is cooled to precipitate HMX.

3. 3. The method according to claim 1 or 2, wherein the concentration of the nitric acid in step i) is 99%.

4. 4. The process according to any one of claims 1 to 3, wherein the reaction vessel in step iii is at 70°C to 75°C.

5. 5. The method of claim 1, wherein the quenching in step iv is caused by mixing the output flow mixture with a quenching agent.

6. 2. The method of claim 1, wherein the reaction mixture is quenched after step iv to precipitate HMX.

7. 7. The method of claim 6, wherein the quenching agent is, for example, an aqueous solution that precipitates HMX.

8. 8. The method of claim 6 or 7, wherein the quenching agent is cooled to less than 10°C.

9. The reactants were TAT:P ２ O ５ : HNO ３ The method according to any one of claims 1 to 8, wherein the ratio of ...

10. Prior to step i), preparing an input flow reagent A comprising TAT (1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane) dissolved in nitric acid at a concentration of greater than 95%; Nitric acid and P with a concentration of over 95% ２ O ５ preparing an input flow reagent B comprising: providing the input flow reagents A and B to the flow reactor; The method according to any one of claims 1 to 9.

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