Process for preparing isocyanates using phosphazine catalysts

Details Process for preparing isocyanates using phosphazine catalysts Process for preparing isocyanates using phosphazine catalysts

1992-10-15

1994-03-29

Dees, Jose G.

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

Organic compounds

Isocyanate esters

560 24, 560115, 560157, 560336, 564 12, 564 13, C07C26304

Patent

active

052986519

ABSTRACT:
A process for preparing isocyanates comprising (a) contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a phosphazene compound or a mixture of a phosphazene compound and an organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines, pyridine and mixtures thereof to produce the corresponding ammonium carbamate salt, and (b) reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent to produce the corresponding isocyanate. A second embodiment comprises recovering the ammonium carbamate salt of step (a) prior to reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent in the presence of an aprotic organic solvent and a phosphazene compound or a mixture of a phosphazene compound and an organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines, pyridine and mixtures thereof.

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