Manufacture of isocyanates
AssigneeAmerican Cyanamid Company
InventorsSteven L. Trenbeath, Allan M. Feldman, Laurence J. Nummy
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Abstract
A process for producing aromatic mono- and polyisocyanates by the addition reaction of isocyanic acid with vinyl aromatics is disclosed. The process is characterized by the slow addition of the olefin to a reaction mass of solvent and isocyanic acid to maintain the isocyanic acid in high excess to unreacted olefin.
Claims7
In the preparation of isocyanates by addition of isocyanic acid to an olefin in an inert solvent and in the presence of a catalyst effective to promote the reaction, the improvement which comprises establishing a reaction mass of isocyanic acid and inert solvent therefor at approximately atmospheric pressure and at a temperature between about 25.degree. and 80.degree. C. and adding the olefin to the reaction mass at a rate such that the molar proportion of remaining isocyanic acid to unreacted olefin is above about 25 to 1, while maintaining said temperature between 25.degree. and 80.degree. C. and maintaining the molarity of unreacted isocyanic acid in said mass between about 1 and about 6.
Dependencies are inferred from the claim text.