Process for the purification of 4,4'-diisocyanatodiphenylmethane

Details Process for the purification of 4,4'-diisocyanatodiphenylmethane Process for the purification of 4,4'-diisocyanatodiphenylmethane

1982-10-25

1983-11-08

Bascomb, Jr., Wilbur L.

Distillation: processes, separatory

And recovering heat by indirect heat exchange

203 74, 203 77, 260453SP, B01D 310, C07C11900

Patent

active

044140746

ABSTRACT:
A new process for the production of very pure 4,4'-diisocyanatodiphenylmethane is disclosed, in which diisocyanatodiphenylmethane isomers which are obtained by distillation from the phosgenation products of aniline/formaldehyde condensates are initially freed from 2,2'- and 2,4'-isomers under certain distillation conditions and are then further worked-up by distillation, in that in a first final stage, from 50 to 90%, by weight of the diisocyanate freed from 2,2'- and 2,4'-isomers is isolated as the head product in the form of pure 4,4'-diisocyanatodiphenylmethane and in a second final stage, another quantity of pure 4,4'-diisocyanatodiphenylmethane is separated as the head product from the distillation of the sump of the first final stage.

REFERENCES:
patent: 3155699 (1964-11-01), Powers
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patent: 3658656 (1972-04-01), Adica et al.
patent: 3816496 (1974-06-01), Schnabel
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patent: 4118286 (1978-10-01), Burns et al.
patent: 4189354 (1980-02-01), Ellendt et al.
patent: 4264723 (1981-04-01), Ichijima et al.

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