Patent GB-627474-A (GB)
Title: Improvements in or relating to a process for the preparation of acetylenic alcohols
IPC: C07C29/42
Filed: 1944-11-07
Abstract: A reaction menstruum consisting of an aqueous solution of potassium hydroxide, a substantially water-insoluble inert organic liquid, other than an acetal or polyether, which forms an azeotrope with water and has a boiling point of at least 100 DEG  C. at atmospheric pressure, and a monohydric alcohol having from 3 to 11 carbon atoms, is subjected to azeotropic distillation to reduce the water-content of the menstruum, the water in the distillate being removed and the inert organic liquid and monohydric alcohol returned to the distillation.  Specified inert organic liquids are aliphatic and aromatic hydrocarbons such as naphtha, kerosene, tetra- and deca-hydronaphthalenes, xylene and ethyl benzene and mono-ethers such as phenyl, butyl and amyl ethers.  Suitable alcohols are 1-propanol, the butanols, methylallyl alcohol, 1-pentanol, isoamyl alcohol, 2- and 4-methyl-2-pentanols, 1-and 2-octanols, undecanol, cyclohexanol, tetrahydrofurfurol, 2-phenylethyl alcohol, 3-phenylpropyl alcohol and other compounds containing an alcohol group such as ethylene and diethylene glycol monoethyl ethers.  Acetylenic alcohols derived from 1-alkynes having a hydrogen atom in the 1-position and aliphatic aldehydes having from 4-8 carbon atoms or aliphatic ketones are recovered as aqueous azeotropes from reaction mixtures consisting of said alcohols, aqueous potassium hydroxide, and the above mentioned inert organic liquids and monohydric alcohols, by fractional distillation.  If the inert organic liquid preferentially forms a water azeotrope, a layer containing said inert liquid is first removed from the reaction mixture and distilled separately.  The acetylenic alcohol recovered as the azeotrope may be purified by removing the water content by a further azeotropic distillation with, for example, benzene, toluene or xylene.  Acetylenic alcohols mentioned are 2-methyl-3-butyne-2-ol, 2 - methyl - 3 - pentyne - 2 - ol, 3 - methyl - 1-pentyne - 3 - ol, 3 : 5 - dimethyl - 1 - hexyne-3 - ol, 3 - methyl - 1 - nonyne - 3 - ol, 1 - hexyne-3 - ol, 6 - ethyl - 3 - decyne - 5 - ol, 1 - nonyne-3 - ol, and 4 - ethyl - 1 - octyne - 3 - ol.  The distillations are steps in a process for preparing acetylenic alcohols for which numerous reactants are specified (see Group IV (b)).  The Specification as open to inspection under Sect. 91 describes reaction menstruums containing substantially water - insoluble inert liquids in general and any monohydric alcohol including phenol and methyl alcohol.  This subject-matter does not appear in the Specification as accepted.ALSO:Acetylenic alcohols are prepared by heating a mixture consisting essentially of solid potassium hydroxide, previously pulverized if it contains less than 13 per cent of water, a monohydric alcohol containing from 3 to 11 carbon atoms, and a substantially water-insoluble organic liquid, other than an acetal or polyether, which forms an azeotrope with water, is inert to the reactants and products and has a boiling point of at least 100 DEG  C. at atmospheric pressure, to the point at which the potassium hydroxide is at least partially molten and water is present in an amount less than one mole. per mole. of potassium hydroxide, cooling the heated mixture with agitation to produce solid potassium hydroxide in finely divided form, absorbing therein a 1-alkyne having a hydrogen atom in the one-position, introducing an aliphatic aldehyde having from 4 to 8 carbon atoms or an aliphatic ketone, hydrolysing the resultant product with water to produce the corresponding acetylenic alcohol and recovering the latter. Alternatively, the inert organic liquid and monohydric alcohol are added to an aqueous solution of potassium hydroxide and water removed by azeotropic distillation, the inert organic liquid and alcohol in the distillate being recycled, until no more water distils over and the residue containing potassium hydroxide with 13 per cent water is cooled with agitation as above. Suitable alcohols are 1-propanol, the butanols, methylallyl alcohol, 1-pentanol, isoamyl alcohol, 2- and 4-methyl-2-pentanols, 1- and 2-octanols, undecanol, cyclohexanol, tetrahydrofurfural, 2-phenylethyl alcohol, 3-phenyl propyl alcohol, and other compounds containing an alcohol group such as ethylene glyco monoethyl ether and diethylene glycol monoethyl ether. Suitable inert organic liquids are aliphatic and aromatic hydrocarbons such as naphtha, kerosene, xylene, ethylbenzene, and tetra- and deca-hydronaphthalene and monoethers such as phenyl, butyl and amyl ethers.  The alkyne is absorped in the reaction menstruuum at temperatures from above its freezing point up to 35 DEG  C.; the aldehyde or ketone is then reacted at from -10 DEG  to +90 DEG  C. After hydrolysis, a water-acetylenic alcohol azeotrope is removed by fractional distillation under reduced pressure and the water removed therefrom by another azeotropic distillation with, for example, benzene, toluene or xylene, to yield the pure alcohol. When the inert organic liquid preferentially forms a water azeotrope, the layer containing the inert liquid is first removed from the hydrolysis mixture and distilled separately.  Examples describe the preparation of 2-methyl-3-butyne-2-ol from acetylene and acetone using xylene or butyl ether and n-butanol as the selected inert liquid and monohydric alcohol; comparative experiments show the effect on yields of omitting the monohydric alcohol and of adding the alcohol after the fusion of the potassium hydroxide in the inert liquid.  A table summarizes the conditions employed in the preparation of 2-methyl-3-pentyne-2-ol, 3-methyl-1-pentyne-3-ol, 3 : 5-dimethyl-1-hexyne-3-ol, 3-methyl-1-nonyne-3-ol, 1-hexyne-3-ol, 6.ethyl-3-decyne-5-ol, 1-nonyne-3-ol and 4-ethyl-1-octyne-3-ol from acetylene and appropriate aldehydes or ketones.  Other alkynes mentioned are propyne, 1-pentyne and phenyl-acetylene. Data is given showing the effect of various alcohols and inert organic liquids used in preparing the reaction menstruum on yield and output per volume of menstruum.  Specification 544,221 is referred to.  The Specification as open to inspection under Sect. 91 states that substantially water-insoluble inert liquids in general and any monohydric alcohol including methanol and phenol may be used in making the reaction menstruum, and is not limited as regards the water content of the fused mixture.  This subject-matter does not appear in the Specification as accepted.