CN111320554A - Improved technology of monomethylhydrazine production process - Google Patents
Improved technology of monomethylhydrazine production process Download PDFInfo
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- CN111320554A CN111320554A CN201911299659.0A CN201911299659A CN111320554A CN 111320554 A CN111320554 A CN 111320554A CN 201911299659 A CN201911299659 A CN 201911299659A CN 111320554 A CN111320554 A CN 111320554A
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- C07C241/00—Preparation of compounds containing chains of nitrogen atoms singly-bound to each other, e.g. hydrazines, triazanes
- C07C241/02—Preparation of hydrazines
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Abstract
An improved technology for preparing monomethylhydrazine is invented on the basis of the process of a hydrochloric acid methanol hydrazine hydrate method, and solves the defects of more by-products, low reaction yield, environmental pollution caused by the formation of highly toxic polyhydrazines in reaction liquid and the like in the conventional process of synthesizing monomethylhydrazine by the hydrochloric acid methanol hydrazine hydrate method, avoids further methyl diversification of a target product monomethylhydrazine generated firstly in the reaction process, ensures the simplified production of the target product, and more importantly, the technology is simplified and environment-friendly, improves the yield and reduces the cost.
Description
Technical Field
The invention relates to the field of organic synthesis, in particular to a new process technology for establishing clean production of a target product by improving a synthesis process for industrially producing monomethylhydrazine
Background
The monomethyl hydrazine is widely applied to the aspects of medicines, pesticides and dyes, and has the advantages of low freezing point, good thermal stability, stable combustion process and the like, so that the monomethyl hydrazine is regarded as a very valuable compound in various industries such as aerospace, missile and the like, the production amount of the raw material is continuously increased along with the large demand of the market, China is also a large country for producing the monomethyl hydrazine, and the annual output is at the top of the world.
A great number of synthetic methods for methylhydrazine are reported, and the current synthetic methods mainly comprise the following methods according to the existing literature:
chlorine-ammonia process
The patent US4192819 disclosed the synthesis of methylhydrazine by chloramine method at the earliest, which mainly uses sodium hypochlorite and ammonia to react to produce chloramine, and then the chloramine reacts with monomethylamine to produce methylhydrazine. While the art is mature in that it is,
but the subsequent separation difficulty of the route is high, the energy consumption in the production process is high, and the equipment cost is high.
Condensation method of hydrazine hydrate benzaldehyde
Hydrazine hydrate is used as a raw material to react with benzaldehyde to generate benzal nitrogen, dimethyl sulfate is added to generate methylhydrazine sulfate, and the methylhydrazine sulfate is neutralized and rectified by sodium ethoxide. The product yield is 60-70%. But the whole reaction raw material cost is high, the reaction process is complex, the production energy consumption is high, the odor in the production process is large, and the industrial production is not facilitated.
Dimethyl sulfate hydrazine hydrate process
Patent CN101402586A discloses a method for producing methylhydrazine sulfate from hydrazine hydrate and dimethyl sulfate by using hydrochloric acid as a protective agent and tetrabutylammonium bromide as a catalyst at 115-125 ℃, and then rectifying and separating the methylhydrazine sulfate under the free condition of strong alkali sodium hydroxide to obtain the required methylhydrazine solution.
The method has the advantages of easily available raw materials, low price, high reaction speed, high yield and the like. But the toxicity of dimethyl sulfate is high, so that potential safety hazards exist, and a large amount of sodium salt which is difficult to treat is remained after the dissociation is finished, so that the treatment cost of the sodium salt is undoubtedly increased, and a very troublesome environmental protection problem is brought, and therefore, the process is difficult to carry out industrial production.
Hydrochloric acid methanol hydrazine hydrate method
In recent years, a new process for preparing methyl hydrazine is proposed by japan hydrazine limited company, and patent JP8298247 discloses a process in which hydrazine monohydrochloride is reacted with methanol, hydrazine dihydrochloride or methyl chloride is used as a catalyst to generate methyl hydrazine hydrochloride at a high pressure and a certain temperature, then methyl hydrazine is dissociated by an alkali dissociation method, and finally methyl hydrazine is distilled by a rectification method. The method has cheap raw materials and high product selectivity. But has the disadvantages of low reaction yield of about 30 percent, high equipment investment and high cost because the reaction is carried out in a high-pressure corrosion-resistant reaction kettle.
The domestic production of monomethylhydrazine (MMH) mainly adopts the two synthesis processes of the chloroammonia method or the hydrochloric acid methanol hydrazine hydrate method. At present, the method of hydrazine hydrate in methanol hydrochloride is mature and widely applied. The main process comprises the following steps: methanol and hydrazine hydrate are used as raw materials, hydrochloric acid and chloromethane are used as catalysts, monomethylhydrazine is prepared under the pressure condition of 0.7-1.3 Mpa, several existing production enterprises in China generally adopt the process (patent CN102516117A), the process has the advantages that the raw materials are easy to obtain, the cost is relatively low, the defects of the process are that a plurality of byproducts are generated, the yield of monomethylhydrazine is low, the methylation of hydrazine is not well controlled, and the like, a large amount of byproducts generated by the process are Unsymmetrical Dimethylhydrazine (UDMH), 1, 2-dimethylhydrazine (1, 2-DMH) and other virulent derivatives of hydrazine hydrate, and the byproducts are asymmetric dimethylhydrazine (UDMH), 1, 2-dimethylhydrazine (1, 2-DMH) and other virulent derivatives of hydrazine hydrate, so that the components of the whole reaction system are complicated, the subsequent separation difficulty is large, the energy consumption of the production process is high, the yield is low, and the production cost is large. The production plant emits thousands of tons of waste liquid to process each year, the waste liquid is a highly toxic dangerous article and is inflammable, and the steam and the air can form explosive mixture and are extremely easy to combust and explode or decompose highly toxic gas when meeting open fire. Therefore, the recovered waste liquid can only be incinerated or decomposed by an incinerator, which not only pollutes the environment, but also wastes resources.
Aiming at the problems in the prior art, the invention provides a new process which is safe in operation, high in yield and environment-friendly by technical improvement of a hydrochloric acid methanol hydrazine hydrate method, and provides a new technical method on the basis of the original synthesis process for synthesizing methylhydrazine by the hydrochloric acid methanol hydrazine hydrate method. The method is most suitable for large-scale industrial production.
Disclosure of Invention
The invention aims to provide an improved process technology on the basis of a hydrochloric acid methanol hydrazine hydrate method process, solve the defects of more byproducts, low reaction yield and the like when the monomethyl hydrazine is synthesized by the hydrochloric acid methanol hydrazine hydrate method at present, prevent the environmental pollution caused by the formation of highly toxic polybasic hydrazines in reaction liquid, improve the yield and reduce the cost. The invention has the main advantages that the process effectively controls side reactions, and the monomethyl hydrazine with high purity can be obtained by separating reactants through processes such as simple rectification and the like, thereby improving the yield and reducing the environmental pollution; greatly improves the production safety and reduces the production cost.
The technical scheme of the invention is as follows: an improved method for a monomethylhydrazine production process comprises the following steps:
a process for preparing high-concentration aqueous solution of monomethylhydrazine includes such steps as adding acidic mixture of oxidant to the mixture of hydrochloric acid, methanol and hydrazine hydrate, stirring, heating to obtain a compound salt, alkali analysis, fine filtering, adding trace reducer to the filtrate, mixing, and rectifying.
1. The components are as follows: the molecular formula of monomethylhydrazine is: CH (CH)3NHNH2(ii) a The oxidant is concentrated sulfuric acid, nitric acid, sodium carbonate peroxide and Cu2+And potassium iodate.
The reducing agent is one of hydrogen sulfate, ammonia gas, sodium bisulfite, sodium sulfite, sulfur dioxide and ferrous sulfate.
The acidic compound is citric acid and SO2、CO2One of sulfuric acid, phosphoric acid, nitric acid, oxalic acid and acetic acid.
The alkaline neutralizing agent is one of ammonia water (or ammonia gas), hydrazine hydrate, sodium hydroxide, sodium carbonate, sodium bicarbonate and calcium oxide.
2. The component ratio is as follows: the molar ratio of the oxidant to the reaction liquid is (0.1-1.3) to 1; the concentration of the acid compound is 2-38% or pure acid gas is used; the concentration of alkali used for neutralization is 10-40% or a solid alkaline compound is used, and the pH of the solution is adjusted to 6.5-11.0; keeping the temperature constant at 5-80 ℃ for 0.5-5 hours.
The process flow is as follows: the method comprises the steps of adding chloromethane as a catalyst in the reaction of a hydrochloric acid methanol hydrazine hydrate method to react mixed solution, namely oxidation reaction, neutralization, suction filtration, adding a reducing agent and rectification, and obtaining high-concentration monomethylhydrazine aqueous solution.
The technical effects are as follows: the invention has the technical effects that by adopting the technical scheme, the further methyl diversification of the target product monomethyl hydrazine generated in the reaction process is avoided, the single production of the target product is ensured, and more importantly, the process is simple and environment-friendly, the yield is improved, and the cost is reduced.
The process of the present invention will now be described in detail with reference to the following examples, which will aid in the understanding of the present invention, but are intended to be illustrative of the invention and are not intended to limit the invention thereto.
Detailed Description
Example 1
Slowly dripping 125g (2.0mol) of 80% hydrazine hydrate into 192.1g (2.0mol) of 38% concentrated hydrochloric acid, keeping the temperature at 20-30 ℃ under stirring for reaction for 2h, adjusting the pH value to 6-7 after the reaction is completed, carrying out vacuum distillation to remove water, mixing the obtained hydrazine hydrochloride with 96g (3mol) of methanol, raising the reaction temperature to 85 ℃, and carrying out condensation reflux for 2-3 h. And distilling the reacted mixed solution to separate methanol and a small amount of water, wherein the methanol can be recycled. The remaining residue was added to 136.0g of 80% by mass hydrazine hydrate to be freed, and the liquid reaction mixture was analyzed to obtain the following results: selective methyl hydrazine: 94.0 percent; selective 1, 1-dimethylhydrazine: 3.7 percent; selectivity is 1, 2-dimethylhydrazine rate: 2.1 percent; selectivity is 1, 1, 1-trimethylhydrazine rate: 0.3 percent. And finally, heating and rectifying the dissociated solution, collecting fractions at 102-110 ℃ to obtain 87.0g, wherein the content of methylhydrazine is 34.3% by gas phase detection. Adding hydrochloric acid into the residual residue to obtain hydrazine monohydrochloride, and returning to the methylation step for recycling.
Example 2
125g (2.0mol) of 80% hydrazine hydrate is slowly dripped into 192.1g (2.0mol) of 38% concentrated hydrochloric acid, the temperature is controlled at 20-30 ℃ under the stirring condition, the heat preservation reaction is carried out for 2h, the pH is adjusted to 6-7 after the reaction is completed, the vacuum distillation is carried out to remove water, the obtained hydrazine hydrochloride is mixed with 96g (3mol) of methanol, the reaction temperature is raised to 85 ℃, the mixture is condensed and refluxed for a period of time, and methane chloride is slowly introduced into the mixed solution to react for 2-3 h. And distilling the reacted mixed solution to separate methanol and a small amount of water, wherein the methanol can be recycled. The remaining residue was added to 136.0g of 80% by mass hydrazine hydrate to be freed, and the liquid reaction mixture was analyzed to obtain the following results: selective methyl hydrazine: 96.0 percent; selective 1, 1-dimethylhydrazine: 1.3 percent; selective 1, 2-dimethylhydrazine: 0.8 percent; selectivity 1, 1, 1-trimethylhydrazine rate: 0.7 percent. And finally, heating and rectifying the solution, collecting fractions at 102-110 ℃ to obtain 96.3g, and detecting the content of methylhydrazine to be 45.0% by gas phase. Adding hydrochloric acid into the residual residue to obtain hydrazine monohydrochloride, and returning to the methylation step for recycling.
Example 3
125g (2.0mol) of 80% hydrazine hydrate is slowly dripped into 192.1g (2.0mol) of 38% concentrated hydrochloric acid, the temperature is controlled at 20-30 ℃ under the stirring condition, the heat preservation reaction is carried out for 2h, the pH is adjusted to 6-7 after the reaction is completed, the vacuum distillation is carried out to remove water, the obtained hydrazine hydrochloride is mixed with 96g (3mol) of methanol, the reaction temperature is raised to 85 ℃, the mixture is condensed and refluxed for a period of time, and methane chloride is slowly introduced into the mixed solution to react for 2-3 h. Adding the mixed reaction solution into mixed solution of sulfuric acid and sodium percarbonate in a distributed manner, stirring, adding CaO into the obtained composite salt after keeping the reaction temperature at 60 ℃ constant for 1h for analysis, precisely filtering, adding a small amount of sodium sulfite into the filtrate, mixing, keeping the solution at 50 ℃ constant for 15min, and analyzing the liquid reaction mixture to obtain the following results: selective methyl hydrazine: 99.9 percent; selective 1, 1-dimethylhydrazine: 0.1 percent; selectivity is 1, 2-dimethylhydrazine: 0 percent; selectivity 1, 1, 1-trimethylhydrazine rate: 0 percent. And finally, heating and rectifying the solution, collecting 102-110 ℃ fractions to obtain 99.3g, wherein the content of methylhydrazine is 44.6% by gas phase detection. Adding hydrochloric acid into the residual residue to obtain hydrazine monohydrochloride, and returning to the methylation step for recycling.
Example 4
125g (2.0mol) of 80% hydrazine hydrate is slowly dripped into 192.1g (2.0mol) of 38% concentrated hydrochloric acid, the temperature is controlled at 20-30 ℃ under the stirring condition, the heat preservation reaction is carried out for 2h, the pH is adjusted to 6-7 after the reaction is completed, the vacuum distillation is carried out to remove water, the obtained hydrazine hydrochloride is mixed with 96g (3mol) of methanol, the reaction temperature is raised to 85 ℃, the mixture is condensed and refluxed for a period of time, and methane chloride is slowly introduced into the mixed solution to react for 2-3 h. Adding the mixed reaction solution into the mixed solution of sulfuric acid and sodium percarbonate in a distributed manner, stirring, adding CaO into the obtained composite salt after keeping the reaction temperature at 60 ℃ for 1h for analysis, and analyzing the liquid reaction mixture to obtain the following results: selective methyl hydrazine: 99.1 percent; selective 1, 1-dimethylhydrazine: 0.9 percent; selectivity 1, 2-dimethylhydrazine rate: 0.1 percent; selectivity 1, 1, 1-trimethylhydrazine rate: 0 percent. And (3) heating and rectifying the solution after precision filtration, collecting the fraction at 102-110 ℃ to obtain 98.1g, and detecting the content of the methylhydrazine by using a gas phase to be 42.0%. Adding hydrochloric acid into the residual residue to obtain hydrazine monohydrochloride, and returning to the methylation step for recycling.
Example 5
125g (2.0mol) of 80% hydrazine hydrate is slowly dripped into 192.1g (2.0mol) of 38% concentrated hydrochloric acid, the temperature is controlled at 20-30 ℃ under the stirring condition, the heat preservation reaction is carried out for 2h, the pH is adjusted to 6-7 after the reaction is completed, the vacuum distillation is carried out to remove water, the obtained hydrazine hydrochloride is mixed with 96g (3mol) of methanol, the reaction temperature is raised to 85 ℃, the mixture is condensed and refluxed for a period of time, and methane chloride is slowly introduced into the mixed solution to react for 2-3 h. Adding the mixed solution of sulfuric acid and sodium carbonate peroxide into the reaction mixed solution in a distributed manner, stirring, adding 80% hydrazine hydrate into the obtained composite salt after keeping the reaction temperature at 60 ℃ for 1h for analysis, carrying out precision filtration, adding a small amount of sodium sulfite into the filtrate, mixing, keeping the solution at 50 ℃ for 15min, and analyzing the liquid reaction mixture to obtain the following results: selective methyl hydrazine: 99.7 percent; selective 1, 1-dimethylhydrazine: 0.15 percent; selectivity 1, 2-dimethylhydrazine rate: 0 percent; selectivity 1, 1, 1-trimethylhydrazine rate: 0 percent. And (3) rectifying, collecting fractions at 102-110 ℃ to obtain 98.0g, wherein the content of methylhydrazine is 41.4% by gas phase detection. Adding hydrochloric acid into the residual residue to obtain hydrazine monohydrochloride, and returning to the methylation step for recycling.
Claims (2)
1. An improved technique for a production process of monomethylhydrazine is characterized in that: adding an acidic mixed solution of an oxidant into a reaction mixed solution realized by using chloromethane as a catalyst in a hydrochloric acid methanol hydrazine hydrate method reaction, stirring, heating to react to obtain a composite salt, performing alkaline analysis, performing precise filtration, adding a trace amount of reducing agent into a filtrate, mixing, and performing rectification to obtain a high-concentration monomethylhydrazine aqueous solution product.
2. The improvement technology of the monomethylhydrazine production process according to claim 1, wherein the improvement technology comprises the following steps: the oxidant is concentrated sulfuric acid, nitric acid, sodium carbonate peroxide and Cu2+And potassium iodate, the reducing agent is one of hydrogen sulfate, ammonia gas, sodium bisulfite, sodium sulfite, sulfur dioxide and ferrous sulfate, and the acidic compound is citric acid and SO2、CO2The alkaline neutralizing agent is one of ammonia water (or ammonia gas), hydrazine hydrate, sodium hydroxide, sodium carbonate, sodium bicarbonate and calcium oxide, and the component ratio is as follows: the molar ratio of the oxidant to the reaction liquid is (0.1-1.3) to 1, the concentration of the acidic compound is 2-38% or pure acidic gas is used, the concentration of alkali used for neutralization is 10-40% or solid alkaline compound is used, the pH of the solution is adjusted to 6.5-11.0, the reaction time is 0.5-5 hours at the constant temperature of 5-80 ℃, and the process flow is as follows: methyl chloride is added in the reaction of the hydrochloric acid methanol hydrazine hydrate method as a catalyst to react mixed solution, namely oxidation reaction, neutralization, suction filtration, addition of a reducing agent and rectification to obtain high-concentration monomethylhydrazine aqueous solution.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114292208A (en) * | 2021-12-27 | 2022-04-08 | 杭州新本立医药有限公司 | Method for preparing methylhydrazine by solid acid catalysis |
| CN115232023A (en) * | 2022-06-23 | 2022-10-25 | 东力（南通）化工有限公司 | Novel process for catalytically synthesizing methylhydrazine |
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| CN114292208A (en) * | 2021-12-27 | 2022-04-08 | 杭州新本立医药有限公司 | Method for preparing methylhydrazine by solid acid catalysis |
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Application publication date: 20200623 |