A method for improving the vacuum system in the process of preparing acid chlorides by acidolysis of benzylidene dichloride

Abstract

The invention discloses a method for the vacuum system in the process of preparing acid chlorides by benzylidene dichloride acidolysis. The raw material benzylidene dichloride used in production is used to replace the traditional water as the vacuum circulation medium, and the vacuum system in the process of acid chloride rectification under reduced pressure is used. The non-condensable material is absorbed into the vacuum circulating liquid tank, and the circulating liquid is cooled by the heat exchanger to remove the heat generated during the spraying process of the circulating medium. The benzylidene dichloride absorbing solution is regularly transferred, returned to the acid chloride synthesis kettle as a material for preparing acid chloride, and at the same time, fresh benzylidene dichloride is added to the vacuum circulating liquid tank. The method improves the vacuum system, avoids the gas-generating reaction of the acid chloride when it meets water, ensures the stable operation of the vacuum system, does not generate organic waste water, recovers the materials in the vacuum tail gas, and reduces the raw material consumption of the acid chloride production.

Description

technical field [0001] The patent of the present invention relates to a method of a vacuum system in the process of preparing acid chlorides by acidolysis of benzylidene dichloride. Background technique [0002] Acyl chloride is an important carboxylic acid derivative with active chemical properties. It can undergo various reactions such as hydrolysis, alcoholysis, ammonia (amine) solution, reaction with organometallic reagents, reduction reaction, α-hydrohalogenation, etc. It is used in organic synthesis, pesticides, etc. , pharmaceutical synthesis, resource environment and other aspects have important applications, [0003] Acyl chlorides are generally prepared by reacting organic acids with phosphorus trichloride, phosphorus pentachloride or thionyl chloride. The main production methods are phosphorus trichloride method, phosphorus pentachloride method, thionyl chloride method, phosgene method, four Carbon chloride method. [0004] Thomas J, McCann in the patent (patent...

AI Technical Summary

Problems solved by technology

If a water ring vacuum pump is used, water is often used to provide a vacuum for the circulating medium. Since acid chlorides are easily hydrolyzed, violent chemical reactions occur when encountering water, and benzylidene dichloride also undergoes hydrolysis reactions in water and hot environments to generate benzaldehyde and hydrogen chloride. , chemical exothermic and hydrogen chloride gas reactions occur in the vacuum circulating water tank, which is not conducive to the stable operation of the vacuum system

Moreover, with the operation of the vacuum circulating water tank, more and more organic materials are accumulated, which are delaminated or emulsified with water, which is not conducive to providing a vacuum, and some organic acids, benzaldehyde, and benzylidene dichloride are dissolved in the water to become organic materials. Wastewater, additional treatment burden

If other organic medium is used as the circulating medium, the material of the water ring vacuum pump is difficult to meet the operation requirements, and the absorption liquid needs to be rectified and recovered

Images