Reactions of lignin model compounds with pulp bleaching chemicals. Cannizzaro-type reaction of tetrachloro- o -benzoquinone with alkali

Abstract

Reaction of tetrachloro-o-benzoquinone 1 with aqueous sodium hydroxide resulted in a Cannizzaro-type disproportionation into tetrachloromuconic acid and tetrachlorocatechol. The tetrachloromuconic acid was isolated and identified by X-ray crystallography as the methyl ester of the cyclized lactone 3. Crystals of C 7 H 3 Cl 3 O 4 , 4, are orthorhombic, a = 9.991 (2), b = 7.981 (1), c = 24.626(2) Å, Z = 8, space group Pna2 1 . The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.033 for 1609 reflections with I ≥ 3σ(I).