Exhaust gas treatment process for paranitrobenzoyl chloride

Abstract

The invention provides an exhaust gas treatment process for paranitrobenzoyl chloride. The process comprises the following steps: adding a toluene solution into a reaction vessel, introducing phosgene into the reaction vessel, and meanwhile, continuing to introduce the phosgene; dropwise adding paranitrobenzoic acid into the reaction vessel, and carrying out stirring while carrying out dropwise adding; introducing nitrogen gas into the solution for first-time gas purging; drying gas subjected to first-time gas purging with a molecular sieve; introducing the dried gas into a recovery kettle, introducing chlorine gas into the recovery kettle, meanwhile, arranging an activated charcoal layer in the recovery kettle, and enabling a mixture of the dried gas and the chlorine gas to pass through the activated charcoal layer; introducing nitrogen gas into the recovery kettle for second-time gas purging, and then, carrying out phosgene extraction on gas subjected to second-time gas purging with a toluene or benzene solution; and introducing the extracted gas into a NaOH solution. According to the process, by adopting the process, exhaust gases, such as carbon monoxide, resulting from reactions can subject to a reaction again to produce the phosgene, and then, the phosgene is recovered.

Description

technical field [0001] The invention relates to the field of plastic fine chemical production, in particular to a tail gas treatment process of p-nitrobenzoyl chloride. Background technique [0002] p-Nitrobenzoyl chloride is a medical raw material used to prepare procaine hydrochloride, p-aminobenzoyl glutamic acid and folic acid, etc.; it can be used as a dye raw material to prepare direct dye brown 100 for leather and paper; It can be used to make acid dyes, food additives (milk powder conditioners), color developing agents and organic synthesis intermediates, identification of alcohols, phenolic reagents, etc. [0003] p-Nitrobenzoyl chloride is an important intermediate in the synthesis of folic acid, procaine hydrochloride, N-p-aminobenzoyl-L-glutamic acid and other vitamin pharmaceutical products, and is also widely used in the production of pigments and color developers . Especially in recent years, with the rise of the feed industry and the development of the info...

AI Technical Summary

Problems solved by technology

There are certain deficiencies in the existing several preparation methods: as phosgene and phosphorus oxychloride are highly toxic substances, it is easy to cause harm to personnel safety and the environment; phosphorus pentachloride is a solid, and it is necessary to add a solvent to accelerate the reaction, which is easy Increase impurities and separation operations; when thionyl chloride is used as the chlorination agent, the reaction time is longer, and column distillation is required to remove impurities, increasing energy consumption, etc., so the direct discharge of the generated tail gas will cause environmental pollution