Benzal chloride

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Benzal chloride
Skeletal formula of benzal chloride
Ball-and-stick model of benzal chloride
Preferred IUPAC name
Other names
  • Benzyl dichloride
  • Benzylidene chloride
  • α,α-Dichlorotoluene
  • PhCl2H
3D model (JSmol)
ECHA InfoCard 100.002.463
EC Number 249-854-8
MeSH Compounds Benzylidene Compounds
RTECS number CZ5075000
UN number 1886
Molar mass 161.03 g/mol
Appearance Colorless liquid
Density 1.254 g/cm3, liquid
Melting point −17 to −15 °C (1 to 5 °F; 256 to 258 K)
Boiling point 205 °C (401 °F; 478 K) (82 °C at 10 mmHg)
0.25 g/L at 39 °C
Vapor pressure 0.6 kPa (45 °C)
Toxic (T), Carc. Cat. 2B, Dangerous for the environment (N)
R-phrases (outdated) 22-23-37/38-40-41
S-phrases (outdated) 36/37-38-45
Flash point 93 °C (199 °F; 366 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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[edit]

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


  1. ^ "BENZAL CHLORIDE". International Programme on Chemical Safety. Retrieved 2007-10-30.
  2. ^ Lipper, Karl-August; Löser, Eckhard, "Benzyl Chloride and Other Side-Chain Chlorinated Aromatic Hydrocarbons", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.o04_o01