GB761817A - Carbamates of acetylenic carbinols and process for their preparation - Google Patents

Abstract

Carbamates of carbinols of the formula HC ­ C.C(R1)(R2)OH, wherein R1 and R2 ar alkyl groups, preferably containing not more than four carbon atoms, are prepared by bringing together an alkali metal cyanate and a solution comprising the carbinol and trichloracetic acid, with or without an additional solvent. As solvents are mentioned dioxan, methylene di-chloride and carbon tetrachloride, and the reaction is preferably effected either by using an excess of carbinol sufficient to dissolve the tri-chloracetic acid, or using a non-polar solvent (CCl4) in the presence of a small excess of the carbinol. In examples: (1) powdered potassium cyanate is added to 3-methyl-1-pentynol-3 in dioxan, and trichloracetic acid in dioxan is slowly run into the cooled solution which is stirred overnight, poured into water, and the carbamate of 3-methyl-1-pentynol-3 isolated by ether extraction and fractional distillation of the dried extract in vacuo. (2) As in (1) but using excess of the carbinol as the solvent. (3) As in (2), heating the reaction mixture at 45-50 DEG C., neutralizing the product with sodium carbonate and separating the precipitated salts; the filtrate is concentrated in vacuo, water added and the carbamate which separates is recrystallized from cyclohexane.