Prepn. of methyl-isocyanate intermediates for insecticides - by passing methyl halide through metal cyanate, catalyst and solvent mixt. at a specified rate

摘要

Prepn. of methylisocyanate (I) by reaction of an alkali and/or alkaline earth metal cyanate with methyl halides in organic solvents at elevated temps. in the presence of a catalyst such as an iodide or bromide of an alkali(ne earth) metal comprises passing the methylhalide through the reaction mixt. at the rate of 0.5-3 mol/hr. mol. cyanate, so that the reaction time is 1-4 min. Ratio of organic solvent to methyl halide is 3-5:1 and (I) is removed continuously from the reaction zone. (I) is an intermediate in the prepn. of e.g. esters of N-methylcarbamide acids which are strong insecticides. The process gives higher yields of (I) than previous processes, but also has a shorter residence time. Essentially 92-97% of the cyanate is converted to (I).