Resource recovery disposal method for scrapped Sieve explosion type tear bomb

Abstract

The invention belongs to the technical field of resource recovery of scrapped chemical defense hazardous articles, and particularly relates to a resource recovery disposal method for scrapped Sieve explosion type tear bombs. Specifically, the invention provides a green process for directionally converting CS in a scrapped projectile body into a high-added-value medical intermediate 2-(2-chlorphenyl) benzimidazole. According to the process, pulverization pretreatment of a main charge grain is achieved through swelling treatment, wet crushing and drying, and CS is efficiently recycled through multi-step dissolution and extraction; cS and o-phenylenediamine are taken as raw materials, six-step continuous reaction of nucleophilic addition, acid-base neutralization, nucleophilic substitution, proton migration / elimination, intramolecular cyclization and oxidative aromatization is carried out, and the CS and o-phenylenediamine are directionally converted into 2-(2-chlorphenyl) benzimidazole. According to the disposal method, high-risk waste is converted into medical intermediates, waste resource utilization is achieved, pollution and safety risks caused by a traditional incineration / blasting method are avoided, and the problem of disposal of current decommissioning tear bombs is solved.

Description

Technical Field

[0001] This invention belongs to the field of hazardous materials resource recycling technology, specifically relating to a method for recycling and disposing of discarded CESE explosive tear gas canisters. Background Technology

[0002] Tear gas, as a mainstream non-lethal riot control device internationally, consists of a projectile structure, a propulsion / explosion unit, and a tear gas stimulant. Based on its mechanism of action, it is classified into three types: jet type (directional aerosol diffusion), grenade type (area coverage), and gun-launched type (kinetic energy driven). Its riot control effectiveness is achieved through a physical-chemical mechanism: in the physical diffusion stage, combustion / explosion disperses the stimulant into micron-sized particles, ensuring full contact with target organs (conjunctiva, respiratory tract, skin); in the chemical activation stage, the stimulant molecules specifically bind to the TRPV1 / TRPA1 receptors of sensory neurons, triggering Ca2+ activation. 2+ Influx and neuropeptide release mediate an inflammatory cascade, ultimately leading to reversible physiological dysfunction. Commonly used irritant components in tear gas include α-chloroacetophenone (CN), o-chlorobenzylmalonium (CS), and capsaicin (OC). With the development of more effective and less toxic CS, CN has gradually been replaced. CS is typically prepared by the condensation of o-chlorobenzaldehyde and malononitrile. For example, American chemists successfully synthesized CS using the Knoevenagel condensation reaction catalyzed by an organic base. CS is highly irritating, chemically stable, and difficult to degrade.

[0003] As high-risk strategic materials, the disposal of decommissioned tear gas munitions is extremely challenging due to its high danger, technical complexity, and numerous stages. Effective disposal of tear gas, especially the irritant, is particularly crucial to prevent potential safety hazards and environmental pollution. Currently, the main methods for disposing of decommissioned tear gas include incineration (incineration, blasting, and chemical destruction) and safe disposal. Incineration and blasting are efficient and low-cost, but come with significant safety hazards and secondary environmental risks. Chemical destruction, while able to convert highly toxic substances into less toxic ones through bond breaking and process pollution control, produces low-value products, essentially still representing resource depletion. Safe disposal technologies, such as composting, while based on the concept of biological transformation, are limited by low efficiency, large land requirements, and inconsistent effectiveness. Ultimately, these traditional disposal methods are generally trapped in the "end-of-pipe treatment" model, failing to overcome systemic drawbacks such as resource waste, secondary pollution, and safety risks, contradicting the core concepts of green, circular, and sustainable development currently being advocated.

[0004] Given the significant drawbacks of the aforementioned methods, the high-value conversion of key components in tear gas is of groundbreaking significance. This method goes beyond simple destruction or disposal; instead, it utilizes chemical conversion to directionally synthesize CS (cementaceous chemical residues) into fine chemicals or functional molecules with higher economic value. This not only completely resolves the safety and environmental hazards but also maximizes resource recycling, creating economic benefits. It represents an innovative treatment direction that aligns with green principles and technological advancements, and signifies a crucial future development direction for the resource-based treatment of end-of-life ammunition (especially ammunition containing special chemical components).

[0005] In summary, existing technologies have not yet achieved efficient separation and targeted conversion of CS into high-value-added products, and there is an urgent need for a green, resource-efficient, and high-value-added processing technology. Summary of the Invention

[0006] This invention aims to provide a green, efficient, and safe process for the recycling and high-value conversion of waste CS explosive tear gas canisters, which converts CS into the pharmaceutical intermediate 2-(2-chlorophenyl)benzimidazole, thereby realizing the resource utilization, harmlessness, and high-value utilization of hazardous waste.

[0007] This invention first achieves the pretreatment of the main charge column into a powder form through swelling treatment, wet crushing and drying, and then efficiently recovers CS through multi-step dissolution and extraction; then, using CS and o-phenylenediamine as raw materials, it undergoes a six-step continuous reaction of nucleophilic addition, acid-base neutralization, nucleophilic substitution, proton migration / elimination, intramolecular cyclization and oxidative aromatization to directionally convert it into 2-(2-chlorophenyl)benzimidazole.

[0008] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a process for the recycling and disposal of decommissioned CESE explosive tear gas canisters, comprising the following steps: Step S1: Extraction and recycling of CS: The main explosive charge is obtained by dismantling the discarded tear gas canisters. The explosive charge is swollen with acetone and then mechanically stirred into a uniform paste. It is then poured into an 8-mesh sieve and filtered into uniform mud particles. After drying, it becomes a powdery agent. The powdery agent consists of CS, RDX, polyvinyl chloride (PVC) and dibutyl phthalate. S1-1 Methanol Extraction: Methanol was used as the solvent, and the powdered reagent was added and extracted at room temperature. After extraction, the mixture was filtered to remove PVC from the main reagent, and then evaporated to dryness to recover methanol and obtain solid product a. S1-2 Chloroform Extraction: Using chloroform as a solvent, solid product a was added and extracted at room temperature; after extraction, the mixture was filtered to remove RDX, and then evaporated to dryness to recover chloroform, yielding solid product b; S1-3 Low-temperature elution: Using ethanol as solvent, add solid product b, crystallize at -4~8 ℃, and filter to obtain solid product c, i.e. CS; Step S2: CS is directionally converted to 2-(2-chlorophenyl)benzimidazole. S2-1: Dissolve CS and sodium bisulfite in an aqueous solution and react at 15℃~25℃ until the solid is completely dissolved to form CS sulfonate. The molar ratio of CS to sodium bisulfite is 1:1 to 1:1.1; S2-2: o-Phenylenediamine reacts with concentrated hydrochloric acid in ethanol to form o-Phenylenediamine monohydrochloride; The molar ratio of o-phenylenediamine to concentrated hydrochloric acid is 1:0.9 to 1:1.1; S2-3: Add the CS sulfonate obtained in step S2-1 to the o-phenylenediamine hydrochloride obtained in step S2-2, add sodium formate, react at room temperature, then heat to 70~75℃, react for 3~5 hours, cool and filter to obtain 2-(2-chlorophenyl)benzimidazole; The molar ratio of o-phenylenediamine monohydrochloride, CS sulfonate and sodium formate is (1.2~1.3):1:(2.4~2.6).

[0009] Preferably, in step S1-1, the amount of methanol used to extract the main drug is 6~150 g·L. -1 .

[0010] Preferably, in steps S1-2, the amount of chloroform used to extract solid a is 40-250 g·L. -1 .

[0011] Preferably, in steps S1-3, the amount of ethanol added to solid b is 6~150 g·L. -1 .

[0012] Preferably, in step S2-1, the CS concentration is 0.05~2 mol / L.

[0013] Preferably, in step S2-1, the presence of CS spots in the aqueous solution is detected by TLC; if no CS spots are found, the reaction ends.

[0014] Preferably, in step S2-2, the concentration of o-phenylenediamine is 0.075~3.0 mol / L.

[0015] Preferably, in steps S2-3, the concentration of sodium formate is 0.1~5.0 mol / L.

[0016] Preferably, in step S2, the molar ratio of CS to sodium bisulfite is 1:1, the molar ratio of o-phenylenediamine to concentrated hydrochloric acid is 1:1, and the molar ratio of o-phenylenediamine monohydrochloride, CS sulfonate, and sodium formate is 1.25:1:2.5.

[0017] In a second aspect, the present invention provides a method for preparing 2-(2-chlorophenyl)benzimidazole from o-chlorobenzylmalonium (CS), comprising step S2 of the method described in the first aspect.

[0018] The idea and principle of this invention is as follows: The development of a high-value conversion pathway for CS, a key component of tear gas, can be achieved by combining in-depth research on its chemical reaction properties with retrosynthetic analysis of high-value target molecules containing CS structural fragments or structural analogs. The CS molecule contains two key functional groups: a highly reactive nitrile group (-CN) and an α,β-unsaturated double bond (-C=C-). Based on its unique chemical properties, CS can be directionally converted into a low-toxicity and high-economic-value product through strategies such as catalytic conversion or nucleophilic addition. The nitrile group hydrolyzes under strong acid catalysis upon heating to an amide (-CONH2), which further hydrolyzes to generate an α,β-unsaturated carboxylic acid (2-chlorocinnamic acid). This intermediate undergoes high-temperature decarboxylation under alkaline conditions, releasing CO2 to generate o-chlorostyrene. The α,β-unsaturated double bond can act as a potentiophilic site, undergoing a Michael addition-intramolecular cyclization-oxidative aromatization tandem reaction with nucleophiles such as o-phenylenediamine to efficiently construct benzimidazole derivatives. This class of compounds is an important group of heterocyclic compounds with broad-spectrum bactericidal, anti-inflammatory, anticancer, and antioxidant activities. They can be applied to food preservation, plant and animal disease control, and the development of antitumor drugs (such as psychotropic drugs). Compared to the industrial raw material o-chlorostyrene, the pharmaceutical value of o-chlorophenylbenzimidazole increases its market price by tens of times, making it a typical high-value-added product. This technology enables the targeted conversion of CS (carbon dioxide) from discarded tear gas canisters into 2-(2-chlorophenyl)benzimidazole, completely eliminating CS toxicity from a safety perspective and avoiding the pollution and safety risks of traditional incineration / explosion methods. From a resource perspective, it transforms high-risk waste into pharmaceutical intermediates, achieving waste resource utilization. Strategically, it addresses the dilemma of disposing of decommissioned ammunition, accelerates equipment upgrades, and establishes a new paradigm of "molecular resource recycling" that aligns with the dual-carbon strategy.

[0019] The beneficial effects achieved by this invention are as follows: The catalyst material provided by this invention, a multi-element transition metal sulfide, based on the synergistic effect of multiple elements, is conducive to exposing the active sites of the catalyst and improving the electron transfer efficiency of the catalyst; the multi-element transition metal sulfide improves the degradation efficiency of organic matter when activating persulfate to degrade water-soluble organic pollutants, and has good application prospects in the field of water environment remediation. Attached Figure Description

[0020] Figure 1 The scanning electron microscopy characterization results of 2-(2-chlorophenyl)benzimidazole prepared in Example 1 of this invention; (a) 50 μm scale (a) 10 μm scale; Figure 2This is a flowchart illustrating the preparation mechanism of the CS-directed conversion to 2-(2-chlorophenyl)benzimidazole according to the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments. It should be noted that this invention is not limited to the following embodiments.

[0022] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0023] Example 1 CS Extraction and Recovery from Discarded Explosive Tear Gas: After pretreatment and dismantling, the main charge of the discarded explosive tear gas is obtained. The main charge is swollen with acetone and then mechanically stirred into a uniform paste. It is then poured into an 8-mesh sieve and filtered into uniform granules. After drying, the loose main charge is obtained. Its main components include CS, RDX, polyvinyl chloride (PVC), and dibutyl phthalate.

[0024] Weigh 10 g of the main drug and place it in a 500 mL single-necked flask. Add 350 mL of methanol and place the flask on a magnetic stirrer to extract at room temperature for 30 min. After extraction, use a circulating water multi-purpose vacuum pump to filter and remove PVC from the main drug. Use a rotary evaporator to perform negative pressure distillation on the filtrate, evaporate to dryness and recover methanol, and obtain solid product a (including CS, RDX and dibutyl phthalate).

[0025] Solid product a was dissolved in 40 mL of chloroform and stirred at room temperature for 30 min. The solution was then filtered to remove RDX. The filtrate was distilled under negative pressure using a rotary evaporator to recover chloroform, yielding solid product b (including CS and dibutyl phthalate). Solid product b was dissolved in 25 mL of ethanol and stirred at room temperature for 30 min. The solution was then refrigerated at 4°C for 60 min and subsequently filtered to obtain solid product c, i.e., CS.

[0026] Example 2 The directed generation of 2-(2-chlorophenyl)benzimidazole from the CS obtained in Example 1 specifically includes the following steps: Preparation of the CS adduct: In a 250 mL round-bottom flask, first add 25 mL of deionized water, then add 50 mmol of sodium bisulfite solid and 50 mmol of the CS obtained in Example 1 while stirring. The suspension is reacted at room temperature (15℃~25℃) for 6 hours until the solid is completely dissolved. The reaction is considered complete when no CS spot is detected by TLC. The reaction solution is the aqueous solution of the adduct. The process is shown in Formula I below: Formula I Preparation of o-phenylenediamine monohydrochloride: In a 250 mL round-bottom flask, first add 25 mL of ethanol, then add 75 mmol of o-phenylenediamine while stirring. At room temperature (20°C), slowly add 75 mmol of concentrated hydrochloric acid dropwise. After the addition is complete, stir the reaction mixture at this temperature for 2 hours. This reaction solution is the 75 mmol o-phenylenediamine monohydrochloride mixture. The process is shown in Formula II below: Formula II Synthesis of 2-(2-chlorophenyl)benzimidazole: In the apparatus prepared above for the reaction of o-phenylenediamine hydrochloride, 50 mmol of an aqueous solution of the CS adduct was added dropwise at room temperature. After the addition was complete, the mixture was stirred at room temperature for 4 hours. Then, 125 mmol of sodium formate was added, and the mixture was stirred at room temperature for 30 minutes. After the solid was completely dissolved, the temperature was raised to 70 °C, and the reaction was carried out for 3 hours. After a large amount of solid precipitated, no CS spot was detected by TLC, and the product spot was obvious. After the reaction was completed, the reaction mixture was cooled to room temperature, filtered, and dried to obtain the product. The filtrate was separated by chromatography to obtain the product. The process is shown in Equation III below: Formula III Five batches of CS were used, and the experiment was repeated five times. The purity of 2-(2-chlorophenyl)benzimidazole was higher than 98%, and the yield was greater than 85%, as shown in Table 1.

[0027]

[0028] The reaction mechanism of Example 2 is as follows Figure 2 As shown: Reaction Mechanism: Using CS and o-phenylenediamine as starting materials, the reaction proceeds via nucleophilic addition, acid-base neutralization, nucleophilic substitution, proton migration and elimination, intramolecular nucleophilic addition cyclization, and oxidative aromatization. Compound 1 undergoes a Michael nucleophilic addition reaction with a nucleophile (NaHSO3) to generate intermediate 8, CS sulfonate. During this reaction, the nucleophile HSO3... - The lone pair of electrons in the sulfur atom exhibits strong nucleophilicity, attacking the highly electron-deficient β-carbon (i.e., the carbon bonded to the benzene ring) in substrate molecule 1, causing the π bond to break and the negative charge to transfer to the α-carbon, forming a carbanion. The carbanion reacts in the reaction system with H₂O or HSO₃. - The provided protons (H +Under the action of ), it is rapidly protonated to form stable CS sulfonate 8; compound 2 undergoes an acid-base neutralization reaction with hydrochloric acid, in which one of the amino groups of compound 2 accepts a proton (H) donated by hydrochloric acid. + ), forming a positively charged -NH 3+ The intermediate group combines with chloride ions in hydrochloric acid to form o-phenylenediamine monohydrochloride 9. Intermediate 8 and 9 undergo nucleophilic substitution to form intermediate 10. In this reaction, the sulfonic acid group in intermediate 8 is easily replaced by the nucleophilic amino group in intermediate 9 to form intermediate 10. Intermediate 10 undergoes acid-base neutralization with sodium formate to form intermediate 4. Intermediate 4 then undergoes two reactions through two pathways: path b: a proton on the C of the CN bond of intermediate 4 is transferred to the -C(CN)2 leaving group to form imine intermediate 5. The other amino group (-NH2) in intermediate 5 acts as a nucleophile to attack the methylene carbon in the molecule to form benzimidazolinite compound 6. Path a: intramolecular nucleophilic substitution and cyclization are achieved through charge movement, while malononitrile molecules are eliminated to form compound 6. Finally, intermediate 6 loses one molecule of H2 under heating and air oxidation conditions, transforming into a fully aromatized stable product, namely the target compound 7 2-(2-chlorophenyl)benzimidazole.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling and disposing of obsolete West explosives tear gas bomb resources, characterized by, The method comprises the following steps: Step S1 extraction and recovery of CS: The main charge column is obtained by disassembling the retired tear gas bomb, and the main charge column is obtained by swelling, crushing and drying; S1-1 methanol extraction: methanol is used as the solvent, and the scattered agent is added at room temperature; after extraction, suction filtration is performed to remove PVC in the main charge, and then methanol is recovered by evaporation to dryness to obtain solid product a; S1-2 chloroform extraction: chloroform is used as the solvent, and solid product a is added at room temperature; after extraction, suction filtration is performed to remove RDX, and then chloroform is recovered by evaporation to dryness to obtain solid product b; S1-3 low-temperature elution: ethanol is used as the solvent, and solid product b is added at-4~8 ℃ low-temperature elution, and suction filtration is performed to obtain solid product c, i.e. CS; Step S2: CS is converted into 2-(2-chlorophenyl) benzimidazole: S2-1: CS and sodium bisulfite are dissolved in an aqueous solution, and the reaction is carried out at 15~25 ℃ until the solid is completely dissolved to form a CS sulfonate; The molar ratio of CS to sodium bisulfite is 1:1~1:1.1; S2-2: o-phenylenediamine is reacted with concentrated hydrochloric acid in ethanol to form o-phenylenediamine monohydrochloride; The molar ratio of o-phenylenediamine to concentrated hydrochloric acid is 1:0.9~1:1.1; S2-3: the CS sulfonate obtained in step S2-1 is added to the o-phenylenediamine hydrochloride obtained in step S2-2, and sodium formate is added, and the reaction is carried out at room temperature, and then the temperature is increased to 70~75 ℃, and the reaction is carried out for 3~5 hours, and then the reaction is cooled and filtered to obtain 2-(2-chlorophenyl) benzimidazole; The molar ratio of o-phenylenediamine monohydrochloride, CS sulfonate and sodium formate is (1.2~1.3):1:(2.4~2.6).

2. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, The dosage of the main charge extracted by methanol in step S1-1 is 6-150 g·L -1 .

3. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, The amount of trichloromethane used in the extraction of solid a in step S1-2 is 40-250 g·L -1 .

4. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, The amount of ethanol added to the solid b in the step S1-3 is 6-150 g·L -1 .

5. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, In step S2-1, the concentration of CS is 0.05~2 mol / L.

6. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, In step S2-1, TLC is used to detect whether CS exists in the aqueous solution, and the reaction is stopped if no CS is detected.

7. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, In step S2-2, the concentration of o-phenylenediamine is 0.075~3.0 mol / L.

8. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, In step S2-3, the concentration of sodium formate is 0.1~5.0 mol / L.

9. The decommissioned Westies explosive tear gas grenade resource recovery disposal method of claim 1, wherein, In step S2, the molar ratio of CS to sodium bisulfite is 1:1, the molar ratio of o-phenylenediamine to concentrated hydrochloric acid is 1:1, and the molar ratio of o-phenylenediamine monohydrochloride, CS sulfonate and sodium formate is 1.25:1:2.

5.

10. A process for the preparation of 2-(2-chlorophenyl)benzimidazole from o-chlorobenzaldehyde malonate (CS) characterized in that, The step S2 part of the method of any one of claims 1~9.

Images