GB783417A - Process for the production of alpha-ethynyl-carbinols - Google Patents

Abstract

An alpha-ethynyl carbinol of the general formula (R1) (R2) C(OH)­CH, wherein R1 and R2 are aliphatic hydrocarbon radicals or (R1)(R2)C is an alicyclic hydrocarbon radical is obtained by treating an aliphatic or alicyclic ketone with an alkali metal acetylide in the presence of acetylene and of an inert organic solvent at a temperature in the range 0 DEG to 25 DEG C. and under a gas pressure of 3 to 12 atmospheres in which the partial pressure of acetylene is between 2 and 8 atmospheres. The alkali metal acetylide may be formed from acetylene and an alkali metal hydroxide, e.g. potassium hydroxide, preferably in the presence of an inert organic solvent at a temperature in the range 0-25 DEG C. and under a gas pressure of from 3 to 12 atmospheres with the partial pressure of acetylene constituting more than 50 per cent of the total pressure and being in the range 2-8 atmospheres. The acetylene both in the production of the alkali metal acetylide and in the reaction with the ketone is preferably diluted with an inert gas, e.g. nitrogen, with the partial pressure of the acetylene being more than 50 per cent of the total gas pressure. The organic solvent with the alkali metal hydroxide in suspension is preferably saturated with acetylene before the ketone is added but it is also possible to add the ketone to a mixture of solvent and potassium hydroxide before the saturation with acetylene. The solvent employed is preferably an ether, e.g. di-isopropyl ether. In examples: (1) a suspension of pulverulent potassium hydroxide in dry isopropyl ether in an autoclave filled with nitrogen at 3.5 atmospheres is saturated with acetylene, the total gas pressure being 8 atmospheres, and a solution of methyl ethyl ketone in di-isopropyl ether is then forced in under nitrogen pressure and acetylene is forced in to give a total gas pressure of 8 atmospheres, the pasty reaction mixture formed is then decomposed with water and the ether layer worked up to yield 3-methylpent-1-yn-3-ol; (2) 3-methyl-but-1-yn-3-ol is obtained from acetone by a process similar to that used in (1); (3) 1-ethynyl-cyclohexanol is obtained from cyclohexanone by a procedure similar to that used in (1); (4) a mixture of pulverulent potassium hydroxide, di-isopropyl ether and methyl ethyl ketone in an autoclave purged with nitrogen and cooled with ice is treated with acetylene to give a total pressure of 8 atmospheres of which the partial pressure nitrogen is 2 atmospheres and the process is continued until no further reduction in pressure occurs. The product is then treated for the recovery of 3-methyl-pent-1-yn-3-ol.