The Upjohn Co.

Kwok K Sun

Henri Ulrich

Adnan A Sayigh

A process is described for the preparation of bis(aminophenyl)alkanes and bis(aminophenyl)cycloalkanes which comprises condensing a m-alkylphenol with an alkanone or cycloalkanone and heating the resulting condensation product with an at least stoichiometric amount of an acid addition salt of aniline or a substituted aniline or a mixture of such amines.

Process for preparing diaminodiphenyl-alkanes

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.

Process for separating 4,4'-diaminodiphenylmethane

An improved process is described for the preparation of bis(aminophenyl)alkanes which comprises heating the corresponding bis(di-alkoxyphenyl)alkane or corresponding cyclic ethers of bis(phenyl)alkanes with an at least stoichiometric proportion of an aniline acid addition salt, optionally in the presence of an inert organic solvent.

Process for the preparation of bis(aminophenyl)alkanes

The use of certain dihydric phenols, alkyl ethers thereof, and alkyl-substituted monohydric phenols, as promoters in the acid catalyzed condensation of phenol and acetone to form Bisphenol-A enables said reaction to be carried out more rapidly, at significantly lower temperatures in some instances, with greater selectivity, i.e. reduction in proportion of undesired by-product, and most significantly, with the use of only catalytic amounts of mineral acid (instead of the large quantity in the conventional process) or the use of the inexpensive solid catalysts, such as acidic clays, which due to their low catalytic ability, are not useful as sole catalyst for this condensation if the promoter is not present. The promoters are readily recoverable for re-use.

Process for the preparation of bisphenol-A

A process is described for the isolation of 4,4'-diaminodiphenylmethane in substantially pure form (of the order of purity of at least 95%) from admixtures thereof with the corresponding 2,4'-isomer and 2,2'-isomer. The isomeric mixture of diamines is heated, optionally in the presence of an inert organic solvent, with at least two equivalents, per mole of said diamine mixture, of a phenol or bisalkylidenephenol. The 4,4'-diaminodiphenylmethane forms a complex with said phenol and the 4,4'-isomer of the diamine is isolated therefrom in substantially pure form by treatment with alkali or by heating to dissociate. The isomeric mixture of diamines used as starting material can be employed in the form of a mixture of polymethylene polyphenyl polyamines containing a major portion of said diamines.

Purification of methylenedianilines

A process is described for the selective removal of 2,2'- and 2,4'-diaminodiphenylmethanes from mixtures containing 2,2'-, 2,4'- and 4,4'-diaminodiphenylmethanes and polyamines by heating these mixtures in the presence of aqueous hydrochloric acid (55 to 95 percent by equivalents based on the total amine in the starting material) and formaldehyde. The process is particularly useful to facilitate the isolation of substantially pure 4,4'-isomer from aniline-formaldehyde condensation products. The pure 4,4'-isomer is a valuable intermediate for polyamides as well as for the corresponding diisocyanate. The by-products of the reaction are oligomeric polymethylene polyphenyl polyamines which are also useful as curing agents and intermediates for polymethylene polyphenyl polyisocyanates and the like.

Purification process for MDA

A process is described for the selective removal of 2,2'- and 2,4'-diaminodiphenylmethane from mixtures thereof with the corresponding 4,4'-isomer by heating the mixture of isomers in the presence of a 1,3,5-tri-arylhexahydro-1,3,5-triazine and a catalyst (aqueous mineral acid). The process is particularly useful in facilitating the isolation of substantially pure 4,4'-isomer from the aniline-formaldehyde condensation. The pure 4,4'-isomer is a valuable intermediate for polyamides as well as for the corresponding diisocyanate. The by-products of the reaction are oligomeric polymethylene polyphenyl polyamines which are also useful as curing agents and intermediates for polymethylene polyphenyl polyisocyanates and the like.

Process for the purification of MDA

2,2'- AND 2,4'-DIAMINODIPHENYLMETHANE ARE SELECTIVELY REMOVED FROM ADMIXTURES THEREOF WITH THE 4,4'-ISOMER BY HEATING THE ISOMER MIXTURE AT 30.degree. TO 100.degree. C in the presence of styrene, .alpha.-alkylstyrenes, or the mono- or diamino nuclear substituted derivatives thereof and a catalyst (mineral acid, clays, diatomaceous earth, zeolites). The styrene or .alpha.-alkylstyrene can be employed as such or generated in situ from a precursor therefor. The process is particularly useful in facilitating the isolation of substantially pure 4,4'-diaminodiphenylmethane from the polyamine mixture obtained by condensation of aniline and formaldehyde.

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Hamden, CT, United States of America

Kwok K Sun