chloroalkane

Chloroalkanes, or alkyl chlorides, are a class of organohalogen compounds in which one or more hydrogen atoms of an alkane have been replaced by chlorine. The simplest members, mono-chloroalkanes, have the general formula CnH2n+1Cl (for n ≥ 1) and include examples such as chloromethane (CH3Cl) and chloroethane (C2H5Cl). When more chlorine atoms are present, the compounds are called dichloro-, trichloro-, etc., but those are typically addressed as chlorinated alkanes rather than under the umbrella term "chloroalkanes".

Preparation: Industrially, alkyl chlorides are commonly prepared by substituting hydroxyl groups or hydrogen with chlorine using reagents such as thionyl chloride (SOCl2), phosphorus trichloride (PCl3), or phosphorus pentachloride (PCl5) from corresponding alcohols or by hydrocarbon chlorination under radical conditions using Cl2 and light (photochemical chlorination). They can also be formed by the addition of HCl to alkenes (depending on regiochemistry) to give alkyl chlorides.

Properties: The C–Cl bond imparts polarity, making alkyl chlorides typically liquids or gases with higher boiling points than the parent alkanes of comparable size. They are good substrates for nucleophilic substitution (SN1 or SN2) and are commonly used as intermediates in organic synthesis. Their reactivity increases with the stability of the carbocation in SN1 or with a primary/secondary substrate in SN2.

Applications: Chloroalkanes serve as solvents and as building blocks in the production of more complex chemicals, including other halogenated compounds. They are often used in the preparation of alcohols, ethers, and plastics precursors, and in certain industrial manufacturing processes such as vinyl chloride generation from chlorinated precursors.

Safety and environmental concerns: Many alkyl chlorides are volatile and may be irritating to the respiratory tract and skin. Some are toxic and possibly carcinogenic with long-term exposure. They can be environmentally persistent and, when combusted, may release hydrogen chloride. Proper handling and engineering controls are necessary in industrial settings.