Method for preparing alkylcyanophenyl

Abstract

The invention discloses a new method of preparing alkyl cyanophenyl. The new method comprises the following steps: alkylbenzene is used as raw material, is processed through chloromethylation to obtain alkyl benzyl chloride first, and then is processed through ammoxidation to prepare the alkyl cyanophenyl. In the new method, the reaction-path is short, the reaction temperature is low, the yield rate is high, and the selectivity is high. The invention also discloses a high efficiency catalyst used for preparing the alkyl cyanophenyl through the ammonia oxidation process. The catalyst is silica gel or a vanadium chromium five-component system loaded by aluminum oxide, wherein, the vanadium chromium five-component system is VaCrbCcDdEeOx; the catalyst can effectively catalyze the alkyl benzyl chloride to act ammoxidation to obtain the alkyl cyanophenyl; the high efficiency catalyst has the advantages of high activity, high product yield rate, good selectivity, high product purity, long service life, simple technology, etc.

Description

technical field [0001] The invention relates to a new method for preparing alkyl benzonitrile and a special catalyst for ammoxidation. It belongs to the technical field of organic chemistry and also belongs to the technical field of organic fine chemicals. Background technique [0002] Alkylbenzonitriles are very important fine chemicals and organic synthesis intermediates; due to the good reactivity of nitrile groups, alkylbenzoic acids, alkylbenzamides, alkylanilines, A series of fine chemicals such as cyanobenzoic acid are widely used in medicine, pesticides, pigments, dyes, rubber, optoelectronic materials and other fields. [0003] The preparation method of alkyl benzonitrile can be divided into following several kinds according to reaction raw material: the one, alkyl aniline diazotization method, the 2nd, alkyl benzoic acid ammoniation method, the 3rd, alkylbenzaldehyde oximation dehydration method, the 4th, Dialkylbenzene ammoxidation method. The first three metho...

AI Technical Summary

Problems solved by technology

The direct ammoxidation of dialkylbenzene (such as xylene) can obtain two kinds of products of phthalonitrile and alkylbenzonitrile, and general alkylbenzonitrile is as the by-product of phthalonitrile; It is undoubtedly a very attractive idea to prepare alkyl benzonitrile through the base benzonitrile stage, but the problem of low selectivity has not been solved so far.

For example, when using tert-butyltoluene as raw material to prepare tert-butylbenzonitrile by gas-phase ammoxidation method, the reaction generally requires a high temperature of about 400°C. Very low, easy to generate phthalonitrile (Chmyr I M, Bukeikhanov N R, Suvorov B V.Oxidative Ammonolysis ofp-Tert-Butyltoluene in the Presence of a Vanadium-Titanium Catalyst.lzv Akad NaukKaz SSR, Ser Khim, 1982, (3 ): 61-64.) In order to improve the selectivity of generating mononitrile, the reaction temperature can be reduced, such as carrying out the liquid-phase ammoxidation reaction at 100~200° C.; it has been found that as the reaction temperature decreases, the The selectivity increases; however, the reaction temperature is too low, the conversion rate of dialkylbenzene and the yield of the product are all very low, which cannot meet the requirements of the application

Therefore, the direct ammoxidation method is difficult to become the synthetic reaction of alkyl benzonitrile

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