Bis(4-cyanatophenyl)-1,1-ethane

Claim 1

A process for preparing bis(4-cyanatophenyl)-1,1-ethane having a viscosity of less than 200 cps at 25° C., a reactivity at 110° C. of less than 0.3 percent trimerization per hour, and containing impurities of less than 50 ppm of tertiary amine and less than 1000 ppm of diethylcyanamide which comprises: a) reacting a solution of cyanogen halide selected from cyanogen chloride or bromide in a halocarbon solvent with a solution of bis(4-hydroxyphenyl)- 1,1-ethane, and a tertiary amine in a halocarbon solvent at a temperature below about -10° C. for a time sufficient to complete the esterification reaction; b) washing the resulting solution with aqueous acid, and c) recovering the cyanate ester product, wherein the cyanogen chloride and the dihydric phenol are present in the amount of about 1.05 to about 1.25 equivalents of cyanogen chloride to one equivalent of dihydric phenol and wherein the tertiary amine is present in the amount of about 1.005 to about 1.05 equivalents per each equivalent of the dihydric phenol.