Isotope exchange reactions of hydrogen in alkyl halides

Summary

• 1. Tert-butyl chloride participates in a hydrogen exchange reaction with anhydrous deuteroacetic acid in the presence of the salts of coordinationally unsaturated metals, viz., FeCl₃, SbCl₅, SnCl₄, ZnCl₂, HgCl₂. No hydrogen exchange is observed in the same medium in the absence of aprotonic acids.

• 2. Kinetic studies show that the reate of exchange depends substantially on the nature of the aprotonic acid. According to their influence on the rate of hydrogen exchange aprotonic acids can be arranged in ths following sequence: FeCl₃∼-SbCl₅>SnCl₄>ZnCl₂>HgCl₂>BF₃.

• 3. The opinion is held that the cause of the described action of aprotonic acids lies in their contribution to the heterolysis of the carbon to chlorine linkage, and that hydrogen exchange in these cases is related to the formation of carbonium ions.