Patent ID: 6818795
Filing Date: 2004-11-16
Classification: C07C

Abstract:
A process for the production of compounds having general formula (I) wherein R represents a hydrogen atom or a C1 -C8 alkyl, C4-C10 cycloalkyl or C6-C12 aromatic radical an n is an integer greater than or equal to one, such as to give a functionality ranging from 2 to 6, which comprises:reacting aniline or one of its derivatives represented by the formula wherein R is as previously defined, and formaldehyde, or a compound capable of producing formaldehyde, in proportions ranging from 2 to 10 moles of aniline per mole of formaldehyde, at a temperature ranging from 10-60Â° C. and in the absence of an acid catalyst, so as to form an aminal mixture in aniline;(b) separating the water from the aminal mixture to a residual concentration of water equal to about 1-2% by weight; (c) optionally diluting the solution previously formed in step (b), in aniline; (d) isomerizing the aminal mixture by feeding it into one or more fixed bed reactors containing a solid acid catalyst selected from a zeolite or a silico-alumina, at a temperature ranging from 100 to 250Â° C., and at atmospheric pressure or at a value which is such as to maintain the reagent mixture in the liquid state; (e) removing the aniline from the methylenedianiline, or its higher homologous products, by means of distillation.