GB350539A - - Google Patents

Abstract

Primary aliphatic amines are separated from secondary and/or tertiary aliphatic amines by treating the mixtures with an aromatic aldehyde of comparatively high boiling-point such as benzaldehyde so as to form a benzylidene compound with the primary amine, distilling off the secondary or tertiary base which has not taken part in the reaction, decomposing the residual compound by heating it with a mineral acid, and separating in known manner the mixture of aldehyde and primary amine thus produced. According to examples (1) a mixture of monoethylamine and diethylamine containing hydrocarbons is separated by adding benzaldehyde to form benzylidene-ethylamine, distilling off the diethylamine and hydrocarbons, decomposing the benzylidene compound with sulphuric acid while passing steam through the liquid, recovering benzaldehyde in the distillate, running the residual liquid into excess of alkali, and distilling off the ethylamine which is liberated. Methylamine may be similarly separated from dimethylamine, or primary butylamine from secondary butylamine. (2) A mixture of ethylamine and diethylamine is separated by forming the addition compound with p-toluylaldehyde or (3) with b -naphthaldehyde and (4) ethylamine is separated from triethylamine by adding benzaldehyde, distilling off the tertiary base, acidifying the residue with hydrochloric acid, distilling the liberated benzaldehyde in steam, and recovering ethylamine by adding alkali to the residue of hydrochloride.