| 摘要 |
Methanol is removed from a methanol-containing mixture by treating the mixture with formaldehyde in the presence of an acetalisation catalyst to convert the methanol to methylal and removing this from the mixture by distillation as soon as it is formed. The formaldehyde may be used in the form of a polymer or as formalin solution. Suitable acetalisation catalysts are, for example, hydrochloric or sulphuric acid, calcium chloride, p-toluene sulphonic acid, cation exchangers, aluminium chloride, zinc chloride, piperidine hydrochloride, sodium bisulphate, ferric chloride, orthosilicic acid esters, titanic acid esters and dimethyl sulphite. If desired the catalyst may be neutralised after the acetalisation is complete by treatment with sodium carbonate, sodium acetate or an organic base. In the examples methanol is removed from a mixture of methanol and (a) methyl acetate, (b) trimethyl borate, (c) acetone, and (d) methyl acrylate. It is stated that the process may be used for the removal of methanol from mixtures of methanol and methyl esters of acrylic or a -alkyl acrylic acids. |
