Phenylacetyl isothiocyanate

When large quantities are used, the distillation should be performed in parts, for on prolonged heating phenylacetyl isothiocyanate decomposes with a heavy loss in yield. 

A. Phenylacetyl isothiocyanate. Twenty-five grams (0.16 mole) of phenylacetyl chloride (Note 1), 100 ml. of benzene, and 53 g. (0.16 mole) of lead thiocyanate (Note 2) are placed in a 1-1., three-necked, round-bottomed flask equipped with a mechanical stirrer and a reflux condenser. The stirrer is started and the mixture is refluxed for 5 hours. A small amount of activated charcoal is added, and refluxing is continued for 5 minutes. The warm mixture is filtered through a Buchner funnel under suction (Note 3), and the solid on the filter is washed with two 50-ml. portions of benzene. The solvent is removed from the filtrate under reduced pressure, and the residue is distilled at once to yield 17.5— 22.7 g. (61-79%) of phenylacetyl isothiocyanate, b.p. 83-91° at about 0.3 mm. It is a colorless liquid that rapidly darkens on standing (Notes 4 and 5). 

CyeUzoHon. Phenylacetyl isothiocyanate is cyclized by aluminum chloride to 2 a-thiohomophthalimide. ... 

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