Benzonitrile

March 12, 2018
Earlier this year, I became a “star”.
What molecule am I?

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.

Benzonitrile fast facts

CAS Reg. No. 100-47-0
Molar mass 103.12 g/mol 
Empirical formula C7H5N
Appearance Colorless liquid
Boiling point 191 °C
Water solubility <5 g/L

 

Benzonitrile hazard information

GHS classification*: flammable liquids, category 4.
H227—Combustible liquid Chemical Safety Warning
GHS classification: acute toxicity, oral, category 4
H302—Harmful if swallowed Chemical Safety Warning
GHS classification: acute toxicity, dermal, category 4
H312— Harmful in contact with skin Chemical Safety Warning
GHS classification: hazardous to the aquatic environment, acute hazard, category 3
H402—Harmful to aquatic life  Chemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

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