Benzal chloride explained

Benzal chloride is an organic compound with the formula C₆H₅CHCl₂.^[1] This colourless liquid is a lachrymator and is used as a building block in organic synthesis.

Preparation and usage

Benzal chloride is produced by the free radical chlorination of toluene, being preceded in the process by benzyl chloride (C₆H₅CH₂Cl) and followed by benzotrichloride (C₆H₅CCl₃):

C₆H₅CH₃ + Cl₂ → C₆H₅CH₂Cl + HCl

C₆H₅CH₂Cl + Cl₂ → C₆H₅CHCl₂ + HCl

C₆H₅CHCl₂ + Cl₂ → C₆H₅CCl₃ + HCl

Benzylic halides are typically strong alkylating agents, and for this reason benzal chloride is treated as a hazardous compound.

Treatment of benzal chloride with sodium gives stilbene.

Most benzal chloride main industrial use is as a precursor to benzaldehyde. This conversion involves hydrolysis in the presence of base:^[2]

C₆H₅CHCl₂ + H₂O → C₆H₅CHO + 2 HCl

Notes and References

1. Web site: BENZAL CHLORIDE. International Programme on Chemical Safety. 2007-10-30.
2. Encyclopedia: Ullmann's Encyclopedia of Industrial Chemistry. Benzyl Chloride and Other Side-Chain Chlorinated Aromatic Hydrocarbons. Karl-August. Lipper. Eckhard. Löser. 2011 . 10.1002/14356007.o04_o01. 978-3527306732 .