Benzyl chloride: Difference between revisions

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 by the free radical process, involving the intermediacy of free chlorine atoms. Side products of the reaction include benzal chloride and benzotrichloride.

Other methods of production 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 plasticizers, flavorants, and perfumes. Phenylacetic acid, a precursor to pharmaceuticals, is produced from 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 in reaction with alcohols, yielding the corresponding benzyl ether, carboxylic acids, and benzyl ester. Benzoic acid (C₆H₅COOH) can be prepared by oxidation of benzyl chloride in the presence of alkaline KMnO_4:

C₆H₅CH₂Cl + 2 KOH + 2 → C₆H₅COOK + KCl + H₂O

Benzyl chloride 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 this 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. In contact with mucous membranes, hydrolysis produces hydrochloric acid. Thus, benzyl chloride is a lachrymator and has been used as in chemical warfare. It is also very irritating to the skin.

References

^ NIOSH Pocket Guide to Chemical Hazards. "#0053". National Institute for Occupational Safety and Health (NIOSH).
^ "Benzyl chloride". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ M. Rossberg et al. "Chlorinated Hydrocarbons" in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchell, A. R. (1989), Vogel's Textbook of Practical Organic Chemistry (5th ed.), Harlow: Longman, p. 864, ISBN 0-582-46236-3.
Henry Gilman and W. E. Catlin (1941). "n-Propylbenzene". Organic Syntheses; Collected Volumes, vol. 1, p. 471.

External links

Categories:

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	Benzyl chloride is prepared industrially by the gas-phase ] reaction of ] with ]:<ref name=Ullmann>M. Rossberg et al. "Chlorinated Hydrocarbons" in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. {{DOI\|10.1002/14356007.a06_233.pub2}}</ref>		Benzyl chloride is prepared industrially by the gas-phase ] reaction of ] with ]:<ref name=Ullmann>M. Rossberg et al. "Chlorinated Hydrocarbons" in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. {{DOI\|10.1002/14356007.a06_233.pub2}}</ref>
	:C<sub>6</sub>H<sub>5</sub>CH<sub>3</sub> + Cl<sub>2</sub> → C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>Cl + HCl		:C<sub>6</sub>H<sub>5</sub>CH<sub>3</sub> + Cl<sub>2</sub> → C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>Cl + HCl
	In this way, approximately 100,000 tonnes are produced annually. The reaction proceeds ~~via~~ ], involving the intermediacy of ~~the~~ chlorine atoms.<ref>{{VogelOrganic5th\|page = 864}}.</ref> Side products of the reaction include ] and ].		In this way, approximately 100,000 tonnes are produced annually. The reaction proceeds by the ] process, involving the intermediacy of free chlorine atoms.<ref>{{VogelOrganic5th\|page = 864}}.</ref> Side products of the reaction include ] and ].

	Other methods exist, such as the ] of ]. Benzyl chloride was first prepared from treatment of ] with ].		Other methods of production exist, such as the ] of ]. Benzyl chloride was first prepared from treatment of ] with ].

	==Uses and reactions==		==Uses and reactions==
	Industrially, benzyl chloride is the precursor to benzyl esters which are used as ], flavorants, and perfumes. ], a precursor to pharmaceuticals, ~~arises~~ ~~via~~ benzyl cyanide, which is generated by treatment of benzyl chloride with sodium cyanide. ]s, used as ]s, are readily formed by alkylation of ]s with benzyl chloride.<ref name=Ullmann/>		Industrially, benzyl chloride is the precursor to benzyl esters which are used as ]<nowiki/>s, flavorants, and perfumes. ], a precursor to pharmaceuticals, is produced from benzyl cyanide, which is generated by treatment of benzyl chloride with sodium cyanide. ]s, used as ]s, are readily formed by alkylation of ]s with benzyl chloride.<ref name=Ullmann/>

	In ], benzyl chloride is used for the introduction of the ] ] ~~for~~ ]s, yielding the corresponding benzyl ether, ~~and~~ ]s, ~~yielding the corresponding~~ benzyl ester. ] (C<sub>6</sub>H<sub>5</sub>COOH) can be prepared by oxidation of benzyl chloride in the presence of alkaline KMnO<sub>4</sub>		In ], benzyl chloride is used for the introduction of the ] ] in reaction with ]s, yielding the corresponding benzyl ether, ]s, and benzyl ester. ] (C<sub>6</sub>H<sub>5</sub>COOH) can be prepared by oxidation of benzyl chloride in the presence of alkaline KMnO<sub>4:</sub>

	C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>Cl + 2 KOH + 2 → C<sub>6</sub>H<sub>5</sub>COOK + KCl + H<sub>2</sub>O		C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>Cl + 2 KOH + 2 → C<sub>6</sub>H<sub>5</sub>COOK + KCl + H<sub>2</sub>O

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

	Benzyl chloride also reacts readily with metallic ] to produce a ].<ref>{{OrgSynth \| author = Henry Gilman and W. E. Catlin \| title = n-Propylbenzene \| collvol = 1 \| collvolpages = 471 \| year = 1941 \| prep = cv1p0471}}</ref> It is preferable over ] for the preparation of ~~benzylic Grignard~~ reagent, since the reaction of the bromide with magnesium tends to form the Wurtz-coupling product ].		Benzyl chloride also reacts readily with metallic ] to produce a ].<ref>{{OrgSynth \| author = Henry Gilman and W. E. Catlin \| title = n-Propylbenzene \| collvol = 1 \| collvolpages = 471 \| year = 1941 \| prep = cv1p0471}}</ref> It is preferable over ] for the preparation of this reagent, since the reaction of the bromide with magnesium tends to form the Wurtz-coupling product ].

	==Safety==		==Safety==
	Benzyl chloride is an ]. Indicative of its high reactivity (relative to alkyl chlorides), benzyl chloride reacts with water in a ] reaction to form ] and ]. Since benzyl chloride is quite ] at room temperature, it ~~can~~ ~~easily~~ ~~reach the~~ mucous membranes ~~where the~~ hydrolysis ~~takes place with production of~~ ]. ~~This explains why~~ benzyl chloride is a ] and has been used as in ]. It is also very irritating to the skin.		Benzyl chloride is an ]. Indicative of its high reactivity (relative to alkyl chlorides), benzyl chloride reacts with water in a ] reaction to form ] and ]. Since benzyl chloride is quite ] at room temperature. In contact with mucous membranes, hydrolysis produces ]. Thus, benzyl chloride is a ] and has been used as in ]. It is also very irritating to the skin.

	==References==		==References==