GB659727A - Process for the recovery of methylol, methanol and alkali metal formates - Google Patents

Abstract

Mixtures consisting of methylal, methyl formate and methanol are treated with aqueous caustic alkali to saponify the formate and resinify any aldehydes present, the methylal and methanol are distilled off and recovered together with an aqueous slurry of crystalline alkali metal formate. The alkali metal formate is decolorized by washing with methylal. The process may be effected continuously the methanol and methylal being distilled off together and subsequently separated. The treated fraction is obtained by the distillation of products made by partially oxidizing hydrocarbons such as butane or propane in the vapour phase. Preferably a small stoichiometric excess of alkali, e.g. NaOH or KOH is used as a strong aqueous solution; 30-40 per cent NaOH at 40-100 DEG C. and 0-50 p.s.i.g. for about 20 minutes being satisfactory. In an example a mixture consisting of 67 per cent methyl formate, 31 per cent methylal, 1 per cent methanol and 1 per cent of acetaldehyde and propionaldehyde is saponified with 30 per cent NaOH at 50-60 DEG C., the mixture being in the saponification vessel for about 20 minutes, and the products are stripped to give an overhead of methylal and methanol which is subsequently separated by aqueous extractive distillation and a bottoms of aqueous sodium formate which after separation from oils and resins is concentrated and the crystals obtained washed with recycled purified methylal.