Trichloromethyl group

The trichloromethyl group is a functional group that has the formula −CCl₃. The naming of is group is derived from the methyl group (which has the formula −CH₃), by replacing each hydrogen atom by a chlorine atom. Compounds with this group are a subclass of the organochlorines. Some notable examples of compounds with this group are trichloromethane H−CCl₃, 1,1,1-trichloroethane H₃C−CCl₃, and chloral HOC−CCl₃.

Structure of the Trichloromethyl group

The trichloromethyl group has a significant electronegativity.^{[citation needed]} For this reason, trichloromethyl-substituted acids, such as trichloromethanesulfonic acid, are often stronger than the original. For example, the acidity constant (pK_a) of trichloroacetic acid HOOC–CCl
₃ is 0.77, whereas that of acetic acid is 4.76.^[1][2]

By the same principle, the trichloromethyl group generally lowers the basicity of organic compounds, e.g. trichloroethanol.

See also

• Trifluoromethyl group
• Trichloromethoxy