GB422139A - Improvements in the manufacture and production of trimethylamine - Google Patents

Abstract

Trimethylamine is separated from mixtures thereof with ammonia by distillation in the presence of a third substance which forms with ammonia an azeotropic mixture of lower boiling point than the azeotropic mixture of trimethylamine and ammonia, but does not form a ternary azeotropic mixture with trimethylamine and ammonia. Suitable substances are low-boiling aliphatic hydrocarbons and ethers. The distillation is preferably effected at a raised pressure, e.g. at the vapour pressure of the mixture at atmospheric temperature, but distillation may also be effected at atmospheric or reduced pressure. When the boiling point of the third substance differs considerably from that of trimethylamine, an excess of the third substance may be added, so that all the ammonia may be removed as azeotropic mixture and the excess of third substance then distilled off. When the boiling point of the third substance is close to that of trimethylamine, the amount of substance added is preferably rather less than is necessary to remove all the ammonia as azeotropic mixture, the remainder of the ammonia being removed as ammonia-trimethylamine mixture. Examples are given describing the distillation of ammoniatrimethylamine mixtures in the presence of n-butane, isobutane, and dimethyl ether; the use of n- or iso-butylene as the third substance is also mentioned. When dimethyl ether is used, the azeotropic mixture can be used, with or without addition of ammonia and methyl alcohol, for the catalytic manufacture of methylamines.ALSO:Trimethylamine is separated from mixtures thereof with ammonia by distillation in the presence of a third substance which forms with ammonia an azeotropic mixture of lower boiling point than the azeotropic mixture of trimethylamine and ammonia, but does not form a ternary azeotropic mixture with trimethylamine and ammonia. Suitable substances are low-boiling aliphatic hydrocarbons and ethers. The distillation is preferably effected at a raised pressure, e.g. at the vapour pressure of the mixture at atmospheric temperature, but distillation may also be effected at atmospheric or reduced pressure. When the boiling point of the third substance differs considerably from that of trimethylamine, an excess of the third substance may be added, so that all the ammonia may be removed as azeotropic mixture and the excess of third substance then distilled off. When the boiling point of the third substance is close to that of trimethylamine, the amount of substance added is preferably rather less than is necessary to remove all the ammonia as azeotropic mixture, the remainder of the ammonia being removed as ammoniatrimethylamine mixture. Examples are given describing the distillation of ammonia-trimethylamine mixtures in the presence of n-butane, isobutane, and dimethyl ether; the use of n-or iso-butylene as the third substance is also mentioned.