Preparation And Properties Of New Dialkyl Dithiocarbamate

The salts and esters of N,N-dialkyldithiocarbamate are a kind of very important organic compounds, and were applied to many fields. The research progresses on application of these compounds were reviewed systematically in this paper. The preparing technologies of the salts and esters of N,N-dialkyldithiocarbamate and the intermediates N-cyanoethyl, N-alkylamine were described and evaluated systematically. Five new compounds with the structure of N-cyanoethyl,N-alkyldithiocarbamate have been synthesized, their structures were confirmed by IR, and their reaction mechanism and preparing technologies were studied systematically. Moreover, the preparing technologies of the sodium salts of N,N-dialkyldithiocarbamate and N-phenyl,N-alkyldithiocarbamate were optimized.In this paper, five secondary amines with the structure of N-cyanoethyl have been synthesized by cyanoethylation using aliphatic primary amine and acrylonitrile as raw materials. The influences of types and amounts of solvents, the molar ratio of reactants and the time and temperature of reaction on the reaction results were studied. The optimum reaction conditions for the preparation of different products were obtained. The average yield (calculated by primary amines) of every secondary amines is more than 82.0%, and the purity of every secondary amines is higer than 97.5%.Five sodium salts with the structure of N-cyanoethyl,N-alkyldithio-carbamate, four sodium salts with the sructure of N,N-dialkyldithiocarba-mate and four sodium salts with the structure of N-phenyl,N-alkyldithio-carbamate have been prepared by crystallizing from different solvents using different secondary amines, carbon disulfide and sodium hydroxide as raw materials. The influences of types and amounts of solvents, the molar ratio of reactants, the time and temperature of reaction, the crystal temperature and the recycling of solvents on the preparation of these compounds were studied, and the optimum operation conditions for the preparation of these products were obtained. The average yield (calculated by secondary amine) of the sodium salt of N,N-dimethyldi-thiocarbamate is 72.5%, and the average yields of the other twelve products are all more than 93.0%. the purities of all these products are higer than 95.2%.The prepared sodium salts of N, N-dialkyldithiocarbamate were used as collectors for the froth flotation of chalcopyrite of Dexing. The experimental results showed that the sodium salts of N-cyanoethyl, N-(n-propyI)dithiocarbamate is the most excellent collector of sulfide minerals in these products, and its flotation properties are better than the common butyl xanthate and SN-9.