Preparation of methylene diphenylene diisocyanates and polymethy

Details Preparation of methylene diphenylene diisocyanates and polymethy Preparation of methylene diphenylene diisocyanates and polymethy

1989-03-09

1990-12-18

Siegel, Alan

Organic compounds -- part of the class 532-570 series

Organic compounds

Isocyanate esters

C07C 6900

Patent

active

049787799

ABSTRACT:
An improved process is provided for the preparation of methylene diphenylene diisocyanates (MDI) and polymethylene polyphenylene poly (isocyanates) (PMDI) by the thermal decomposition of a methylene diphenylene bis (dialkylurea) or a polymethylene polyphenylene poly (alkylurea) in a solvent in the presence of an organic sulfonic acid or sulfonated aromatic ion exchange resin as a promoter for conversion of the urea groups to the corresponding isocyanate.

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Iwakura et al Bull. Tokyo Inst. Tech. 13, 25(195); Chem. abs. 44, 3924e (1950).
Bennet et al, J. Am. Chem, Soc. 75, 210(1952).

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