Process for synthesis of N-(hydrocarbyl)substituted-p-menthane-3-carboxamide

This invention provides an improved process for synthesizing carboxamides which involves reacting 3-p-menthyl halide with magnesium to form 3-p-menthylmagnesium halide Grignard reagent, and reacting the Grignard reagent with hydrocarbyl isocyanate at a temperature below about -20 DEG C. to form N-hydrocarbyl-p-menthane-3-carboxamide product. The product comprises a mixture of geometric isomers in which the 3-p-menthyl:3-p-neomenthyl weight ratio is at least 4:1 and can be as high as 9:1 under optimal conditions. This invention also provides a novel process for producing acylurea compounds such as N-(3-p-menthylcarbonyl)-N-t-butyl-N'-t-butylurea.