Organochlorides

Organochlorides, also known as chlorocarbons, are a group of organic compounds that contain at least one covalently bonded chlorine atom. These compounds are a subset of the broader family of halocarbons. Organochlorides are diverse in their structures and applications, ranging from simple molecules like methyl chloride (CH3Cl) to complex polymers such as Polyvinyl chloride (PVC). Due to their widespread use and persistence, some organochlorides have significant environmental and health impacts.

Properties and Classification

Organochlorides can be classified based on their structure and the type of carbon-chlorine bond present. Aliphatic organochlorides have chlorine atoms bonded to sp3-hybridized carbons, while aromatic organochlorides have chlorine atoms bonded to sp2-hybridized carbons in an aromatic ring, as seen in Chlorobenzene.

The physical properties of organochlorides, such as boiling point, melting point, and solubility, vary widely and are influenced by the number and position of chlorine atoms in the molecule. Generally, the presence of chlorine increases the density and decreases the flammability of these compounds compared to their hydrocarbon counterparts.

Synthesis

Organochlorides are synthesized through various chemical reactions. One common method is the free radical chlorination of hydrocarbons, which involves the reaction of chlorine gas with hydrocarbons in the presence of light or heat. Another method is the addition of hydrogen chloride to alkenes, known as hydrochlorination.

Applications

Organochlorides have a wide range of applications. They are used as solvents (Chloroform, Carbon tetrachloride), refrigerants (Freon), plasticizers, and in the manufacture of plastics (PVC), synthetic rubber, and other polymers. Some organochlorides, such as DDT, have been used as pesticides, although their use is now restricted due to environmental concerns.

Environmental and Health Impact

Many organochlorides are persistent in the environment and bioaccumulate in wildlife and humans, leading to significant health and ecological concerns. Compounds such as DDT, PCBs, and Dioxins are known for their long-term persistence and toxicity. Exposure to high levels of certain organochlorides can lead to various health issues, including cancer, reproductive disorders, and endocrine disruption.

Regulation and Remediation

Due to their environmental persistence and potential health risks, the production and use of certain organochlorides are regulated under international agreements such as the Stockholm Convention on Persistent Organic Pollutants. Remediation of contaminated sites and water bodies involves various strategies, including bioremediation, which utilizes microorganisms to degrade organochlorides into less harmful substances.

See Also

• Halogenation
• Persistent organic pollutant
• Chlorinated solvent