YIELD AND PURITY COMPARISON OF DIMETHOATE MANUFACTURING PROCESSES - HOMOGENEOUS REACTION, 2-PHASE UNCATALYZED REACTION, AND PHASE-TRANSFER CATALYSIS

The process for manufacturing dimethoate (O,O-dimethyl S-methylcarbamo ylmethyl phosphorodithioate) should provide high yields of highly pure product which requires no further purification steps. A comparison of dimethoate yield and purity obtained by different manufacturing proce sses is presented. Ethanol, isopropanol, acetone, ethyl methyl ketone, and isobutyl methyl ketone were the solvents used when the reaction w as carried out in one single homogeneous phase. In heterogeneous aqueo us-organic solvent medium, an analysis by linear regression techniques has revealed temperature, reaction time, and organic solvent volume a s the operational variables with statistical significance above 95% on the dimethoate purity, while only temperature was significant on gros s and net yields. The phase transfer catalysis did not improve purity and yield obtained in heterogeneous solvent medium with any of the stu died catalysts, namely methyltrioctylammonium chloride, tetrabutylammo nium bromide, tetraoctylammonium bromide, tetraphenylphosphonium bromi de, and tetrabutylphosphonium bromide.