Method for synthesizing nitromethane

Abstract

The invention discloses a method for synthesizing nitromethane, and relates to the technical field of synthesis of compounds with nitryl connected to a saturated noncyclic carbon atom. The method comprises the following steps: stirring and dissolving raw materials sodium nitrite; dripping a raw material dimethyl sulfate in a stirring state, and reacting; filtering the reaction liquid under a stirring state in the post-treatment, separating solid and liquid phases, decompressing and distilling the liquid phase to obtain a nitromethane coarse product, and rectifying to obtain a nitromethane finished product; adding a solvent and a phase transfer catalyst before the raw material dimethyl sulfate is dripped, wherein the boiling point of the solvent is lower than 100 DEG C, the solvent is used for controlling the reaction temperature, and the reaction temperature is 20-60 DEG C. According to the method, the reaction temperature can be easily controlled, the generation of a side product methyl nitrite can be reduced, the reaction yield can be improved, and spark generated in the rectifying process can be reduced, potential safety hazard can be reduced, and the product purity can be increased.

Description

technical field [0001] The present invention relates to the technical field of synthesis of compounds in which nitro groups are attached to saturated acyclic carbon atoms. Background technique [0002] Nitromethane is an important organic chemical product and organic synthesis intermediate. It is a colorless and transparent oily liquid with aromatic taste and certain volatility. ), refractive index 1.3817, flash point 35°C; partially miscible with water, its aqueous solution is acidic, soluble in alcohol, ether, acetone, carbon tetrachloride, dimethylformamide and caustic alkali solution. [0003] Nitromethane is miscible with most organic compounds and is an excellent solvent for aromatic hydrocarbons, alcohols, ketones, ethers, esters and carboxylic acids. It has the characteristics of good selectivity, low viscosity and low volatility. It is widely used in the synthesis of polymer materials, and can also be used in the preparation of explosives, rocket fuel, pesticides, ...

AI Technical Summary

Problems solved by technology

[0012] If the reaction temperature is too high, there will be two side effects

The first is that the decomposition of dimethyl sulfate is accelerated, and the sulfuric acid generated by the decomposition reduces the pH of the reaction system, the catalytic effect of soda ash is reduced, and the reaction time is prolonged, and the decomposition of the raw material dimethyl sulfate causes the incomplete reaction of sodium nitrite to cause the total yield Reduced, product purity decreased

The second is that the reaction temperature is too high will make the side reaction product methyl nitrite (CH 3 ONO) increased, which further led to a decrease in the total yield of the reaction, and made the rectification process prone to generate sparks and other factors that endanger the environment and safety

[0016] After the reaction is over, simple filtration to remove solid salts followed by distillation and rectification will lead to two adverse consequences

One is that the solid salt will coat or absorb part of nitromethane, resulting in product loss; the other is that there will be some dissolved salt solids in the liquid product, which will affect the subsequent distillation process

These two factors will also lead to a decline in the yield of nitromethane

[0017] Especially in the large-scale production process, it is difficult to control the temperature during the reaction, and the harmful gas of methyl nitrite is produced, which not only causes a decrease in yield, but also affects the surrounding environment

What is more serious is that during the rectification process, sometimes sparks or even sparks are generated in the kettle, which constitutes a serious safety hazard and leads to low purity of the final product