Benzyl chloride

Not to be confused with benzoyl chloride.

Benzyl chloride

Benzyl chloride 100px
Names
IUPAC name chlorophenylmethane
Other names α-Chlorotoluene BnCl chloromethylbenzene
Identifiers
CAS Number	100-44-7 Y
ChEBI	CHEBI:615597 Y
ChEMBL	ChEMBL498878 Y
ChemSpider	13840690 Y
EC Number	202-853-6
Jmol 3D model	Interactive image Interactive image
KEGG	C19167 Y
PubChem	7503
UNII	83H19HW7K6 Y
InChI InChI=1S/C7H7Cl/c8-6-7-4-2-1-3-5-7/h1-5H,6H2 Y Key: KCXMKQUNVWSEMD-UHFFFAOYSA-N Y InChI=1/C7H7Cl/c8-6-7-4-2-1-3-5-7/h1-5H,6H2 Key: KCXMKQUNVWSEMD-UHFFFAOYAV
SMILES ClCc1ccccc1 c1ccc(cc1)CCl
Properties
Chemical formula	C7H7Cl
Molar mass	126.58 g/mol
Appearance	colorless to slightly yellow liquid
Odor	pungent, aromatic
Density	1.100 g/cm3
Melting point	−39 °C (−38 °F; 234 K)
Boiling point	179 °C (354 °F; 452 K)
Solubility in water	very slightly soluble (0.05% at 20°C)
Solubility	soluble in ethanol, ethyl ether, chloroform, CCl4 miscible in organic solvents
Vapor pressure	1 mmHg (20°C)
Refractive index (nD)	1.5415 (15 °C)
Vapor pressure	{{{value}}}
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

Benzyl chloride, or α-chlorotoluene, is an organic compound with the formula C₆H₅CH₂Cl. This colourless liquid is a reactive organochlorine compound that is a widely used chemical building block.

Preparation

Benzyl chloride is prepared industrially by the gas-phase photochemical reaction of toluene with chlorine:

C₆H₅CH₃ + Cl₂ → C₆H₅CH₂Cl + HCl

In this way, approximately 100,000 tonnes are produced annually. The reaction proceeds via free radical, involving the intermediacy of the chlorine atoms. Side products of the reaction include benzal chloride and benzotrichloride.

Other methods exist, such as the Blanc chloromethylation of benzene. Benzyl chloride was first prepared from treatment of benzyl alcohol with hydrochloric acid.

Uses and reactions

Industrially, benzyl chloride is the precursor to benzyl esters which are used as plasticizer, flavorants, and perfumes. Phenylacetic acid, a precursor to pharmaceuticals, arises via benzyl cyanide, which is generated by treatment of benzyl chloride with sodium cyanide. Quaternary ammonium salts, used as surfactants, are readily formed by alkylation of tertiary amines with benzyl chloride.

In organic synthesis, benzyl chloride is used for the introduction of the benzyl protecting group for alcohols, yielding the corresponding benzyl ether, and carboxylic acids, yielding the corresponding benzyl ester. Benzoic acid (C₆H₅COOH) can be prepared by oxidation of benzyl chloride in the presence of alkaline KMnO₄

C₆H₅CH₂Cl + 2 KOH + 2 [O] → C₆H₅COOK + KCl + H₂O

It may be used in the synthesis of amphetamine-class drugs, and for this reason sales of benzyl chloride are monitored as a List II drug precursor chemical by the US Drug Enforcement Administration.

Benzyl chloride also reacts readily with metallic magnesium to produce a Grignard Reagent. It is preferable over benzyl bromide for the preparation of benzylic Grignard reagent, since the reaction of the bromide with magnesium tends to form the Wurtz-coupling product 1,2-diphenylethane.

Safety

Benzyl chloride is an alkylating agent. Indicative of its high reactivity (relative to alkyl chlorides), benzyl chloride reacts with water in a hydrolysis reaction to form benzyl alcohol and hydrochloric acid. Since benzyl chloride is quite volatile at room temperature, it can easily reach the mucous membranes where the hydrolysis takes place with production of hydrochloric acid. This explains why benzyl chloride is a lachrymator and has been used as in chemical warfare. It is also very irritating to the skin.

External links

• International Chemical Safety Card 0016
• SIDS Initial Assessment Report for benzyl chloride from the Organisation for Economic Co-operation and Development (OECD)
• CDC - NIOSH Pocket Guide for Chemical Hazards - Benzyl chloride