Organic isocyanate cpds. prepd. from prim. amine(s) - by reaction with carbon di:oxide and hexa:methyl:di:silazane with an acid catalyst

摘要

Organic isocyanates are prepd. by reacting (1-6C) prim. amine with carbon dioxide and hexamethyldisilazane in the presence of an acid catalyst at 40-200 degrees C and then decomposing the resulting silyl carbamate with a dehydrating agent at 0 to 350 degrees C. Suitable acid catalysts include mineral or organic acid, sulphocationites or phosphoric acid cationites. Isocyanates are intermediates in the synthesis of 2,6-bis(methylcarbaminoxymethyl)pyridine an antisclerotic, alpha-naphthyl N-methylcarbamate a herbicide and for cyclohexylcabodiimide a reagent and polymer stabiliser. The process avoids the use of toxic phosgene and explosive azides yet gives good yields.