Patent GB-772721-A (GB)
Title: Manufacture of esters of carbamic acids with tertiary and secondary acetylenic alcohols
IPC: C07C271/06
Filed: 1953-04-10
Abstract: The invention relates to carbamic acid esters of secondary and tertiary acetylenic carbinols having the general formula <FORM:0772721/IV(b)/1> wherein R1, R2, R3 and R4 each represent hydrogen or a monovalent hydrocarbon radical and R4 represents a monovalent hydrocarbon radical, or R5 and R4 together represent a divalent aliphatic hydrocarbon radical, with the exception that when R3 represents hydrogen and either R4 is a monovalent hydrocarbon radical or R4 and R5 together represent a divalent aliphatic hydrocarbon radical, then R1 and R2 are not one a hydrogen atom and the other a monovalent aliphatic hydrocarbon radical.  The compounds have hypnotic activity.  The carbamates may be prepared by transforming acetylenic carbinols of the general formula <FORM:0772721/IV(b)/2> into the desired esters by a method known to be capable of use for converting alcohols into carbamic esters in which the carbamyl radicals have the formula <FORM:0772721/IV(b)/3> i.e. in actual use or described in the literature, R1-R5 being as defined above.  Thus, the alcohols may be reacted with carbamic acid halides <FORM:0772721/IV(b)/4> where X is a halogen atom or halo-formic acid esters of the acetylenic carbinols, produced for example by reacting the alcohols with carbonic acid di-halides, may be reacted with ammonia or amines of the general formula <FORM:0772721/IV(b)/5> To prepare N-mono-substituted carbamic esters, the acetylenic carbinols may be reacted with an isocyanate R-NCO, where R represents a hydrocarbon radical.  In examples: (1) carbamyl chloride is reacted with 3-methyl pentine(1)-ol-(3) yielding the carbamic ester of the acetylenic carbinol which is converted by catalytic hydrogenation to the carbamic acid ester of methyl diethyl carbinol; (2) the same acetylenic carbamate is prepared by reacting the acetylenic carbinol with phosgene and treatint the resulting halo-formate with ammonia; (3)-(4) the carbamate of 1-ethinyl cyclohexane-ol-(1) is likewise prepared; (5) 1-ethinyl cyclohexane-ol is refluxed with phenyl isocyanate in pyridine to give N-phenyl carbamic acid ester of the carbinol and diphenyl urea; (6) 1-propinyl cyclohexanol-1 is reacted as in (1) to give the carbamic acid ester of propinyl-cyclohexanol and (1)-phenethinyl-cyclohexanol may be reacted in like manner; (7) butine-(1)-ol-(3) is reacted with phosgene to yield the halo-formate which is converted into the urethane by ammonia; (8) similarly, ethinyl-cyclohexenyl carbinol is converted into its carbamate; (9) endomethylene cyclohexenyl-ethinyl carbinol is reacted with carbamyl chloride to form its carbamic ester; (10) 1-ethinyl cyclohexanol is reacted with diethyl carbamyl chloride to yield its diethyl carbamic ester; (11) 1-ethinyl cyclohexanol is reacted with phosgene in toluene while adding trimethylamine in toluene dropwise; the trimethyl amine hydrochloride formed is removed as a precipitate and ammonia is passed into the filtrate containing the haloformate of the carbinol so yielding the carbamic ester; the trimethylamine hydrochloride is treated with caustic soda in specified manner to recover the free base for further use.