The bromochlorination of phenyl-and alkyl-substituted acetylenes with tetrabutylammonium dichlorobromate (1−)(1) in dichloromethane was found to be anti-stereospecific and nonregiospecific (regiospecific in the case of phenylacetylene). Whereas the addition of molecular bromine chloride (2) to phenyl-substituted acetylenes was found to give nonstereospecific and regiospecific adducts, the reaction of alkyl-substituted acetylenes ...