The Addition of Hydrogen Bromide to Crotonic Acid in Carbon Tetrachloride Solution and the Oxygen Effect

Abstract

Abstract (1) Hypotheses suggested to explain the orientation of hydrogen bromide in the addition to the ethenoid compound have been briefly reviewed and critisized. (2) Allowing the mixture of hydrogen bromide and oxygen to react with crotonic acid in carbon tetrachloride, three products, β-bromobutyric acid, crotonic acid dibromide and α-hydroxy-β-bromobutyric acid, have been isolated. (3) Oxygen has been found not to accelerate the addition of hydrogen bromide to crotonic acid in carbon tetrachloride solution in the dark. (4) It is concluded that in the addition of hydrogen bromide to crotonic acid in the presence of oxygen, this participates in the reaction producing free bromo-radical acid and bromine atoms, the latter being attached to the β-carbon atom of crotonic acid, but that the chains involving these cannot develop because of the ready reaction of the bromo radical acid with oxygen rather than with hydrogen bromide.