Practical Synthesis of 2,2,5,5‐Tetrachloro‐1,6‐Hexanedioic Acid, from Trans‐1,2‐Cyclohexanediol or Cyclohexanone, Involving Oxidation of 3,3,6,6‐Tetrachloro‐1,2‐Cyclohexanedione

Abstract

AbstractTrans‐1,2‐cyclohexanediol was quantitatively converted into 3,3,6,6‐tetrachloro‐1,2‐cyclohexanedione (2) by treatment with chlorine in dimethylformamide. The hydrate of the dione was oxidized by aqueous potassium permanganate to afford the title acid 1 in 91% overall yield. An alternative low cost preparation was elaborated, providing 2 in 61–74% yield starting from cyclohexanone in a three step procedure without isolation of intermediates. The reaction sequence involves substitution of α‐dichloro‐ and trichlorocyclohexanones by sodium acetate in acetic acid and chlorination of the resulting 2‐hydroxy‐ and 2‐acetoxy‐2‐cyclohexenones in dimethylformamide.