GB701093A - Manufacture of cyclic alcohols and esters thereof - Google Patents

Abstract

A process for the preparation of cyclic alcohols comprises heating an alcohol selected from isopropyl alcohol and secondary butyl alcohol in the liquid phase and in the presence of an alkali metal hydroxide or an alkali metal alcoholate to a temperature in excess of 150 DEG C. and separating from the reaction mixture the cyclic alcohol produced. 1:1:3-Trimethylcyclohexanol-5 and a substituted cyclohexanol of formula C12H24O, respectively, are the cyclic alcohols produced, and as by products are obtained methyl isobutyl carbinol and an octyl alcohol respectively. The products are separated by fractional distillation. Potassium hydroxide, e.g. in amount 1 to 10 per cent., is a suitable condensing agent. To form an alkali metal alcoholate, the alcohol starting material may be mixed with an alkali metal hydroxide and the mixture dehydrated by distillation in the presence of benzene. The preferred reaction temperature is 250 DEG to 300 DEG C. As a solvent which may be present during the condensation, there may be used a hydrocarbon. When isopropyl alcohol is condensed, methyl isobutyl alcohol is a suitable diluent, and may be recycled after isolation from the reaction products. The reaction is preferably carried out in metal vessels, e.g. of steel, stainless steel or nickel and with finely divided metal, e.g. copper bronze as catalyst. Preferably more than 20 per cent. of the initial alcohol is condensed. In examples (1) and (5) isopropyl alcohol is heated at 290 DEG C. with potassium hydroxide in an autoclave; (2) to (4) isopropyl alcohol, potassium hydroxide and benzene are dehydrated by ternary distillation. The solution, in which more than half the potassium hydroxide has been converted to potassium isopropylate is passed continuously through a stainless steel tube at 80 atmospheres. A table shows the percentage conversion and yields of 1:1:3-trimethyl-cyclohexanol-5 and methyl isobutyl carbinol when working at 250 DEG , 274 DEG and 296 DEG C.; (9) secondary butyl alcohol is heated at 250 DEG C. with potassium hydroxide to yield an octyl alcohol and a substituted cyclohexanol C12H24O; (10) secondary butyl alcohol containing potassium secondary butylate is passed continuously through a heated tube at 264 DEG -266 DEG C. at 80 lbs./sq. inch. The products may be converted to esters by heating with a carboxylic in the presence of a mineral acid. Example (1) describe the preparation of 1:1:3-trimethyl-cyclohexyl acetate by heating the alcohol with acetic anhydride. The di(1:1:3-trimethyl-cyclohexyl) esters of sebacic, adipic and phthalic acids are prepared in further examples by heating 1:1:3-trimethyl cyclohexanol and sulphuric acid with the appropriate acid while distilling off water azeotropically. Specification 701,098 is referred to.