A NEW METHOD FOR MIXED HALOGENATION. N-CHLOROAMINE-PHOSPHORUS BROMIDE SYSTEM AS A SYNTHETIC EQUIVALENT OF THE MIXED HALOGEN Cl⁺Br⁻

Abstract

A new method for the mixed halogenation of alkenes has been proposed based on the reaction of olefins with N-chloroamines in the presence of phosphorus bromide or oxybromide. The plausible reaction mechanism and the results of reactions with a number of model unsaturated compounds such as cyclohexene, 1-heptene, ethyl cinnamate, norbomene and those from the bicyclo[2.2.1]heptane series are discussed. In the reactions with reactive olefins this reagent acts as a synthetic equivalent of the unknown mixed halogen [Cl⁺Br⁻] with «abnormal» polarity of halogen atoms. The same reactions activated by PCl₃ or POCl₃ result in dichlorides in yields near to quantitative.

Key Words:

• Bromochlorination
• Halogenation
• N-chloroamines
• phosphorus bromides