Phenyl cyanate (CAS NO.: ), which is also known as Cyanic acid, phenyl ester, could be produced through the following synthetic routes.

A 1-L, three-necked, round-bottomed flask equipped with a mechanical stirrer, thermometer, and a 200-mL pressure-equalizing dropping funnel with a stopper is charged with 160 g (50.9 mL, 1.0 mol) of bromine and 150 mL of water. The mixture is stirred rapidly while cooling in an ice–salt bath to -5°C, and a solution of 49.0 g (1.0 mol) of sodium cyanide in 150 mL of water is added dropwise over a 40–50 min period while maintaining the temperature of the reaction mixture at -5 to 5°C. The resulting solution is stirred an additional 5–10 min. A solution of 89.5 g (0.95 mol) of phenol in 300 mL of tetrachloromethane is added in one portion to the flask. The resulting mixture is stirred vigorously while 96.0 g (131 mL, 0.95 mol) of triethylamine is added dropwise over a 30–40-min period at such a rate that the temperature does not exceed 5–10°C. After an additional 15 min of stirring, the mixture is transferred to a separatory funnel, the organic phase is separated and the aqueous layer is extracted twice with 50-mL portions of tetrachloromethane. The organic phases are combined and washed three times with 50-mL portions of water and then dried over polyphosphoric anhydride (P₂O₅). The drying agent is removed by filtration and the solvent is removed by distillation under reduced pressure using a rotary evaporator at 20°C (25 mm). A few drops of polyphosphate ester are added to the remaining liquid and the product is distilled through a 20-cm Vigreux column to give 85–96 g (75–85%) of phenyl cyanate, bp 77–79° (13 mm), n_D20 1.5094–1.5100, d₄20 1.096. The product is a colorless liquid with a pungent odor.

Notice: These operations, which involve toxic reagents, should be conducted in an efficient hood.