Since acid is liberated in the course of the reaction, the reaction is autoinhibited in the absence of buffering capacity of the solution. Thus, to lower the pH of a 0. IM solution of I in water to a value of 4.0, at which the rate of dehydrobromination is negligible, only 0.05% I must be converted. This explains the cause of the low pH values of aqueous solutions of I, whereas impurities of II in them cannot be detected by the method of NMR spectroscopy. ...