difluoromethylene

Difluoromethylene is a term used in organic and organofluorine chemistry to describe a carbon-centered fragment bearing two fluorine substituents. In common usage it denotes either the difluoromethylene group (-CF2-), a carbon bonded to two fluorines and to two other substituents, or the difluoromethylidene unit (=CF2) when the carbon forms a double bond to another atom. The phrase thus covers two related motifs: a saturated CF2 bridge and an unsaturated =CF2 unit.

The difluoromethylene unit is often introduced via difluorocarbene (CF2) chemistry. Difluorocarbene can be generated in situ from chlorodifluoromethane with a base or from difluoromethyl sulfone derivatives; the difluoromethyltrimethylsilane reagent (TMSCF2H) with fluoride sources is another common route. Reactions include addition of difluorocarbene to alkenes to give difluorocyclopropanes and difluoromethylation of carbonyls or other substrates to furnish difluoromethylated products.

The difluoromethylene motif occurs in a range of compounds, including polymers such as polyvinylidene fluoride (PVDF), which contains repeating units -CH2-CF2-. This unit contributes to high chemical resistance, thermal stability, and dielectric properties, making PVDF and related materials useful in membranes, coatings, and electronics. In medicinal chemistry, difluoromethyl and difluoromethylene groups are used to tune acidity, lipophilicity, and metabolic stability, and to serve as bioisosteres that influence pharmacokinetic and pharmacodynamic properties.

Related topics include the difluoromethyl group, difluorocarbene chemistry, and PVDF.