Improvements in and relating to the separation of primary and tertiary nitrogen bases from mixtures thereof

摘要

Aniline is recovered from mixtures containing it and tertiary cyclic nitrogen bases, e.g., pyridines, by distilling such mixtures, e.g., coal tar bases, in presence of a paraffin fraction so that the aniline is distilled off in the form of an aniline-paraffin azeotropic mixture while the tertiary bases are separated as a higher boiling fraction or residue. The aniline is then separated from the paraffins (a) by fractional distillation in the presence of water (b) by distilling off the aniline-paraffin azeotropic mixture to leave residual aniline (c) by washing the mixture with acid and recovering the aniline as aniline salt. 75 gallons of coal tar bases distilling 5 per cent. at 184 DEG C. and 95 per cent. at 189 DEG C. and 25 gallons of a paraffin mixture distilling 5 per cent. at 181 DEG C. and 95 per cent. at 199 DEG C. were charged into a still with fractionating column, condenser and separator arranged to return the top layer separated to the still and take off the bottom layer. The mixture was distilled with a column top temperature of from 165 to 172 DEG C. 40 gallons of product obtained showed a content of 7 per cent. paraffins which were removed as an azeotrope with aniline by further distillation to 184 DEG C. the receiver being then changed and the residual aniline collected. The azeotrope condensate was utilised for treating a further batch.