A mixture of 2,3-dichloro-1,4-naphthoquinone (5 gm), trans 4-(4-chlorophenyl)-cyclohexane-1-carboxylic acid (6.06 gm) and silver nitrate (2.47 gm) is taken in acetonitrile (60 ml) and the mixture is heated to reflux, maintaining good stirring. Then a solution of ammonium persulphate (14.23 gm) in water (77 ml) is added through a dropping funnel over a period of 1-2 hrs. The mixture refluxed for 4 hrs. Then it is cooled in ice for about 1 hr after which it is filtered. The solid is extracted with hot methylene chloride (100 ml×3). The organic layer is dried over anhydrous sodium sulphate and concentrated to get light brownish yellow solid. This on crystallization from acetonitrile afforded the trans compound as yellow crystals (1.5 gm).
