Difluoromethylation of some C–H acids with chlorodifluoromethane under conditions of phase transfer catalysis (PTC)

Selected C–H acids react with difluorocarbene generated from chlorodifluoromethane with concentrated aqueous solution of sodium hydroxide, and a catalyst, benzyltriethylammonium chloride (TEBAC) in benzene or THF affording C-difluoromethyl substituted derivatives. This process is restricted to C–H acids of pKa ≅ 16.3–19.1. The observed facts are rationalized.