Process for preparing di(aminophenyl)methanes

Details Process for preparing di(aminophenyl)methanes Process for preparing di(aminophenyl)methanes

1975-07-24

1977-08-02

Hines, Robert V.

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

260 25AT, 260453AM, 2605705P, 2605709, C07C 8508

Patent

active

040395804

ABSTRACT:
A process is described for the preparation of polymethylene polyphenyl polyamines containing from 40 to 60 percent by weight of diamine and also containing markedly less high molecular weight polyamines than products hitherto available. Phosgenation of the polyamines gives the corresponding mixture of polymethylene polyphenyl polyisocyanates of markedly lower viscosity and lighter color than products hitherto available, and yielding polymer foams which are substantially white in color.
The process comprises condensing aniline and formaldehyde (molar ratio 4-10:1) in the absence of catalyst, separating water from the resulting aminal mixture, contacting the aminals at 20.degree. C to 60.degree. C with a solid catalyst (diatomaceous earths, clays, zeolites) until formation of benzylamines is substantially complete, distilling aniline from the resulting benzylamines under reduced pressure and below 150.degree. C until the aniline content is 3 to 22 percent by weight, and contacting the resulting product with a solid catalyst (diatomaceous earths, clays, zeolites) at 100.degree. C to 190.degree. C until conversion to polymethylene polyphenyl polyamines is complete.

REFERENCES:
patent: 3362979 (1960-01-01), Bentley
patent: 3676497 (1972-07-01), Recchia et al.
patent: 3857890 (1974-12-01), Recchia et al.

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