Benzonitrile

Benzonitrile, the simplest cyanoaromatic, is a clear liquid with an almond-like odor. Methods for synthesizing it include

• heating sodium benzenesulfonate with NaCN,
• adding benzenediazonium chloride to a hot aqueous solution of NaCN and CuSO₄,
• oxidizing toluene in the presence of ammonia,
• dehydrating benzamide, and
• treating bromobenzene with CuCN or NaCN.

Despite these many synthetic methods, the only uses for benzonitrile are as a solvent or a precursor to benzoguanamine, a derivative of melamine. But recently, the molecule was the subject of a “stellar” discovery.

Brett A. McGuire, at the National Radio Astronomy Observatory in Charlottesville, VA, and collaborators identified benzonitrile in interstellar dust. They estimate that the dust cloud is 430 light-years away. This is the first aromatic molecule to be discovered in space, even though astrochemists estimate that 10% of all interstellar carbon consist of polynuclear aromatics.