Photochemical transformation of tetrabromofuran by oxygen into 2,3,4,4-tetrabromobut-2-en-4-olide in the solid state

Abstract

The solid-state photo-oxidation (1)→(2) recorded by Torrey in 1897 has been verified and structure (2) confirmed; a possible mechanism for the transformation involving free radicals is suggested. In contrast, the bromination (5)→(2) reported by Hill and Cornelison in 1894 could not be repeated despite many attempts. An ionic mechanism for the preparation (4)→(6) is proposed; the semi-aldehyde (6) in solution exists solely in the lactol form (7).