| 摘要 |
1500466 Preparing poly(aminophenyl)methylenes and corresponding isocyanates UPJOHN CO 20 May 1976 [27 June 1975] 20886/76 Heading C2C A mixture of di(aminophenyl)methane and oligomeric polymethylene polyphenyl polyamines is prepared by heating a substantially water-free mixture of aminals derived from reaction of an aromatic amine and formaldehyde with a catalyst selected from diatomaceous earths, clays and zeolites at 20-55‹ C. until the reaction mixture contains 80-100% by weight of the corresponding benzylamines, adjusting the temperature to 55-70‹ C. until from 75- 90% by weight of the benzylamines have been converted to methylene polyphenyl polyamines and finally raising the temperature to 80-101‹ C. until conversion is complete. The product mixture may particularly comprise at least 90% by weight of the diamine, at least 80% of which will usually be the p,p<SP>1</SP>-isomer. The catalyst may be kieselguhr, tripolite, diatomite, infusional earth, attapulgus clay, kaolin, fuller's earth, bentonite, montmorillonite or a natural or synthetic zeolite and may be dried at 100- 500‹ C. prior to use. A mixture of methylene bis(phenyl isocyanate) and its oligomers is obtained from the above mixture by phosgenation in toluene. |
