Abstract: A process for preparing an aromatic polyamine mixture including 4,4?-methylenedi(phenylamine) and higher homologues of MDA is provided. The process includes steps of (i) reaction of aniline with formaldehyde by means of an acid catalyst to form a crude product mixture (I), (ii) neutralization of the crude product mixture (I) and removal of the salts formed; (iii) isolation of aniline; (iv) distillation of the resulting crude product mixture so as to separate off (iv-1) a mixture (II) of MDA isomers (II-1) containing from 8 to 20% by weight of 4,4?-methylenedi(phenylamine) and not more than 0.3% by weight of secondary components (II-2) and (iv-2) a low boiler mixture of at least 55% by weight of secondary components (II-2) and MDA isomers (II-1); and (v) recirculation of the mixture (II).

Abstract: The present invention relates to a process for hydrogenating a mixture (G1) in the presence of a catalyst, where the mixture (G1) comprises at least one colorless amine and at least one color-imparting component. As a result of the hydrogenation step, the at least one color-imparting component is firstly partially, preferably fully, hydrogenated, while the colorless amine, in particular aniline, is not hydrogenated or hydrogenated to only a very small extent. The color-imparting components which cause the discoloration of the amine which is itself in principle colorless are thus removed by hydrogenation, as a result of which purification of the colorless amine or the mixture (G1) is achieved.

Abstract: A process for preparing an aromatic polyamine mixture including 4,4?-methylenedi(phenylamine) and higher homologues of MDA is provided. The process includes steps of (i) reaction of aniline with formaldehyde by means of an acid catalyst to form a crude product mixture (I), (ii) neutralization of the crude product mixture (I) and removal of the salts formed; (iii) isolation of aniline; (iv) distillation of the resulting crude product mixture so as to separate off (iv-1) a mixture (II) of MDA isomers (II-1) containing from 8 to 20% by weight of 4,4?-methylenedi(phenylamine) and not more than 0.3% by weight of secondary components (II-2) and (iv-2) a low boiler mixture of at least 55% by weight of secondary components (II-2) and MDA isomers (II-1); and (v) recirculation of the mixture (II).

Abstract: The present invention relates to a process for hydrogenating a mixture (G1) in the presence of a catalyst, where the mixture (G1) comprises at least one colorless amine and at least one color-imparting component. As a result of the hydrogenation step, the at least one color-imparting component is firstly partially, preferably fully, hydrogenated, while the colorless amine, in particular aniline, is not hydrogenated or hydrogenated to only a very small extent. The color-imparting components which cause the discoloration of the amine which is itself in principle colorless are thus removed by hydrogenation, as a result of which purification of the colorless amine or the mixture (G1) is achieved.

Abstract: A process for the chlorination of alkylanilines is provided allowing a highly selective chlorination in the meta-position of the aromatic ring. This is achieved by reacting a mixture comprising the alkylaniline and sulfuric acid with chlorine. This process allows a meta-chlorination with a selectivity of more than 90%.

Abstract: A process for the chlorination of alkylanilines is provided allowing a highly selective chlorination in the meta-position of the aromatic ring. This is achieved by reacting a mixture comprising the alkylaniline and sulfuric acid with chlorine. This process allows a meta-chlorination with a selectivity of more than 90%.