Benzyl chloride, or α-chlorotoluene, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

. This colorless 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 Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon with the chemical formula , often abbreviated as , where Ph stands for the phenyl group. It is a colorless, water Water is an inorganic compound with the c ...

with

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

: : In this way, approximately 100,000 tonnes are produced annually. The reaction proceeds by the

free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabolic disorders Metabolism ...

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 The Blanc chloromethylation (also called the Blanc reaction) is the chemical reaction of aromatic rings with formaldehyde and hydrogen chloride to form chloromethyl arenes. The reaction is catalyzed by Lewis acids such as zinc chloride. The reac ...

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

. Benzyl chloride was first prepared from treatment of

benzyl alcohol Benzyl alcohol (also known as α-cresol) is an aromatic alcohol with the formula C6H5CH2OH. The benzyl group is often abbreviated "Bn" (not to be confused with "Bz" which is used for benzoyl), thus benzyl alcohol is denoted as BnOH. Benzyl a ...

with

hydrochloric acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

Uses and reactions

Industrially, benzyl chloride is the precursor to benzyl esters, which are used as plasticizers, flavorants, and

perfume Perfume (, ) is a mixture of fragrance, fragrant essential oils or aroma compounds (fragrances), Fixative (perfumery), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agre ...

s. Phenylacetic acid, a precursor to pharmaceuticals, is produced from benzyl cyanide, which in turn is generated by treatment of benzyl chloride with

sodium cyanide Sodium cyanide is a compound with the formula Na C N and the structure . It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also expl ...

Quaternary ammonium salt In organic chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure , where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium ion () and the primary, secondary, ...

s, used as

surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...

s, are readily formed by alkylation of

tertiary amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

s with benzyl chloride. Benzyl ethers are often derived from benzyl chloride. Benzyl chloride reacts with aqueous sodium hydroxide to give dibenzyl ether. In

organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

, benzyl chloride is used to introduce the benzyl

protecting group A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis. In man ...

in reaction with

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

s, yielding the corresponding benzyl ether,

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

s, and benzyl ester.

Benzoic acid Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...

() can be prepared by oxidation of benzyl chloride in the presence of alkaline : : 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 The Drug Enforcement Administration (DEA) is a Federal law enforcement in the United States, United States federal law enforcement agency under the U.S. Department of Justice tasked with combating illicit Illegal drug trade, drug trafficking a ...

. Benzyl chloride also reacts readily with metallic

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

to produce a

Grignard reagent Grignard reagents or Grignard compounds are chemical compounds with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromi ...

. 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 Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...

. Indicative of its high reactivity (relative to alkyl chlorides), benzyl chloride slowly reacts with water in a

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

reaction to form

and

. In contact with mucous membranes, hydrolysis produces hydrochloric acid. Thus, benzyl chloride is a lachrymator and has been used in chemical warfare. It is also very irritating to the skin. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S.

Emergency Planning and Community Right-to-Know Act The Emergency Planning and Community Right-to-Know Act of 1986 is a United States federal law passed by the 99th United States Congress located at Title 42, Chapter 116 of the U.S. Code, concerned with emergency response preparedness. On Octobe ...

(42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.

References

External links

* *
CDC - NIOSH Pocket Guide for Chemical Hazards - Benzyl chloride
{{Authority control Organochlorides Lachrymatory agents IARC Group 2A carcinogens Benzyl compounds

Preparation

Uses and reactions

Safety

See also

References

External links