| 摘要 |
A process is described for the isolation of 4,4'-diaminodiphenylmethane in substantially pure form (of the order of 99% purity) from admixtures thereof with the corresponding 2,4'-isomer and 2,2'-isomer. The dihydrochloride of the isomeric mixture of diamines is heated in the presence of an inert organic solvent with a mixture of isomers of the free diamine, in which the amount of the 4,4'-isomer is at least equal to that of the 2,4'-isomer in the dihydrochloride isomeric mixture. The isomeric mixture of the diamines may be employed in the form of a mixture of polymethylene polyphenyl polyamines containing a major portion of said diamines. The reaction product consists of the insoluble dihydrochloride of substantially pure 4,4'-diaminodiphenylmethane and a solution which is enriched in 2,4'-isomer as compared with the starting mixture of diamines.
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