The addition of hydrogen chloride to allene and 1, 2-butadiene at-78" involves attack at a terminal methylene group of the allenic system. Allene requires a catalyst such as bismuth trichloride and yields a mixture of 2-chloropropene and 2, 2-dichloropropane. 1, 2-Butadiene yields a mixture of trans-and cis-2-chloro-2-butene in the ratio 87/13; 2-butyne is also formed but does not add hydrogen chloride under the conditions. The orientation of addition of ...
