Tetrachlorocyclopropene
Tetrachlorocyclopropene is a chemical compound with the formula C3Cl4. A colorless liquid, the compound is a reagent used to prepare acetylene derivatives and in organic synthesis. It was first reported by Tobey and West. It is prepared by addition of dichlorocarbene to trichloroethylene and then further treating the resultant pentachlorocyclopropane with base to perform dehydrochlorination.
The compound is used to prepare arylcyclopropanones by a two-step, one-pot procedure beginning with a Friedel-Crafts-like arylation:
The aryltetrachlorocyclopropenes are then hydrolyzed to give the keto-alcohol:
The Friedel-Crafts-like arylation employs a Lewis acid catalyst. Treatment of tetrachlorocyclopropene with aluminium trichloride gives the trichlorocyclopropenium ion, which has been isolated as its tetrachloroaluminate salt. X-ray crystallography confirms the structure, revealing very short C-Cl bonds.