Trichloromethyl group
{{Short description|Functional group, formula –CCl3}}
File:Trichloromethyl group.svg
The trichloromethyl group is a functional group that has the formula {{chem2|\sCCl3}}. The naming of is group is derived from the methyl group (which has the formula {{chem2|\sCH3}}), 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 {{chem2|H\sCCl3}}, 1,1,1-trichloroethane {{chem2|H3C\sCCl3}}, and chloral {{chem2|HOC\sCCl3}}.
The trichloromethyl group has a significant electronegativity.{{cn|date=May 2018}} For this reason, trichloromethyl-substituted acids, such as trichloromethanesulfonic acid, are often stronger than the original. For example, the acidity constant (pKa) of trichloroacetic acid {{chem|HOOC}}–{{chem|CCl|3}} is 0.77, whereas that of acetic acid is 4.76.{{Cite web|url=http://www.chemspider.com/Chemical-Structure.109615.html|title=Trichloromethyl {{!}} CCl3 {{!}} ChemSpider|website=www.chemspider.com|access-date=2018-08-26}}{{Cite web|url=https://webbook.nist.gov/cgi/cbook.cgi?ID=C3170807&Mask=800|title=Trichloromethyl radical|website=webbook.nist.gov|language=en|access-date=2018-08-26}}
By the same principle, the trichloromethyl group generally lowers the basicity of organic compounds, e.g. trichloroethanol.