Research On The Synthesis Of 3, 5-Dimethylanlline

3,5-dimethylaniline is an important chemical intermediate, and be widely used in the Pharmaceutical, pesticides, and pigments industry and so on. It can be used as raw material for synthesis kinds of dyes which have Excellent properties,such as C.I.149 is a kind of red dye and C.1. Direct Green 33 is green. In addition, it also be used as material for synthesis thiophenol in Pharmaceutical and pesticides industry. At present, the process of this product is not mature, and the demand of 3,5-dimethylaniline at home mostly depends on importation, therefor developing an efficient process which can adapt to plant-scale production has a great deal of profits.Mesitylene way and 2,4-Dimethylaniline translocation way were used in this paper, Synthetic route of the two ways were improved, and the synthetical conditions were optimized. The desired results were as follows:1. Mesitylene way With mesitylene as raw materials, and reaction with a certain concentration of dilute nitric acid,then the 3,5-dimethyl benzoic acid is produced and the yield was 60%; 3,5-dimethyl benzoic acid reaction with thionyl chloride,3,5-dimethyl chloride was obtained and then drop it into ammonia,received 3,5-dimethyl benzamide, at last 3,5-dimethylaniline were obtained van Hofmann degradation and the yield was 45%; The oxidization of mesitylene and Hofmann degradation from 3,5-dimethylbenzamide were the most important study in this paper, and mole ratio of raw materials and synthetical conditions were optimized. The dynamics of Hoffman degradation reaction was determined during 0-30℃, from the curve we concluded that the order of the reaction is n=1, activation energy Ea=1.04x 105 J/mol.2.2,4-Dimethylaniline translocation way 3,5-dimethylaniline has been synthesized by using 2,4-dimethylaniline as a raw material, it could be obtained through acylation, nitration, hydrolysis,deamination and reduction. But, the synthetic route is too long sothat the yield is low,and in which the reaction process would pollute on environment seriously,including nitration, hydrolysis,deamination. Acccrding to the characteristics of these reactions, acylation and nitration, hydrolysis and deamination can be combined respectively so that the synthetic procedure could be reduced to three steps instead of five In this paper.Using this method, not only reduce the probability polluting on environment when dealing with the intermediate of the reaction, but also increase the yield of the product.The yield of product through this synthetic route was 72%. Compared with the two methods, the synthetic route of mesitylene way was short,and reaction conditions was mild, but the yield was low because it were so hard to increase the yield of oxidization of mesitylene and Hofmann degradation. It would be industrialized if the yield could be increased. The synthetic route of the second method was long and would pollute on environment seriously,but which have been industrialized because the yield was high.The intermediates and the final product 3,5-dimethylaniline that synthesized in the thesis are characterized by using FTIR and H1-NMR.