PROCESS FOR THE PREPARATION OF POLYAMINES OF THE DIPHENYL METHANE SERIES WHICH ARE RICH IN ORTHO ISOMERS

摘要

Mo-1914 LeA 18,671 PROCESS FOR THE PREPARATION OF POLYAMINES OF THE DIPHENYL METHANE SERIES WHICH ARE RICH IN ORTHO. ISOMERS The instant invention is directed to a process for the preparation of polyamines of the diphenyl methane series which are rich in ortho isomers, which comprises: (a) reacting an aromatic amine with formaldehyde to produce N-substituted pre-condensates; (b) removing the water formed in this reaction as well as any water introduced in the form of aqueous formaldehyde solution; (c) rearranging said precondensates in the presence of aromatic amine salts of strong acids to the corresponding primary amines substituted on the aromatic nucleus; (d) neutralizing said aromatic amine salts of strong acids; and (e) subsequently working up in known manner the resulting reaction products; wherein the quantities of reactants and of said strong acids are calculated so that the total quantity of aromatic amine used corresponds to an aromatic amine/formaldehyde molar ratio of from 4:1 to 20:1, and the total quantity of strong acid added, based on the total quantity of aromatic amine, corresponds to an aromatic amine/acid equivalent ratio of from 10:1 to 1,000:1, and at least half of the total quantity of aromatic amine used is combined with the acid to form an aromatic amine/aromatic amine salt mixture; said aromatic amine/aromatic amine salt mixture is heated to a temperature of from 100 to 200.degree.C, said N-substituted pre-condensate, which has been maintained at a temperature of from 0 to 100.degree.C, is introduced into this mixture; and said rearrangement of the pre-condensate is then completed at a temperature within the range of from 100 to 250.degree.C. LeA 18,671