Trimerization of aromatic isocyanates catalyzed by certain ammonium salts
AssigneeThe General Tire & Rubber Company
InventorsHubert J. Fabris, Edwin M. Maxey, Heinz Uelzmann
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Abstract
Quaternary ammonium salts or inorganic and organic oxygen acids having pK values (where pK is the negative log of the dissociation constant) for at least one of the dissociable hydrogen atoms equal to or greater than 2.0 in aqueous solution are employed as extremely efficient catalysts for trimerization of organic isocyanates, particularly aromatic isocyanates, to isocyanurates and for urethane formation.
Claims8
A method which comprises reacting organic isocyanates in contact with at least 0.01 part by weight of said isocyanates of a compound displaying catalytic activity for exothermic cyclic trimerization of organic isocyanates and for urethane formation, said compound corresponding to the structural formula (NR.sub.4).sub.y A in which
- A is an anion derived from an acid having a pK value, in aqueous solution at substantially room temperature, of 2.0 or greater and being free of substituents which can react with isocyanates under conditions of trimerization and being selected from the group consisting of inorganic oxygen acids, carboxylic acids and carbonic acid,
- each R is any organic group other than A and free of any substituents and functional groups which can react with isocyanates under conditions of trimerization, no more than one R per N containing an aromatic ring attached directly to N, and
- y is a whole number equal in value to the valence of A.
Dependencies are inferred from the claim text.