A mixture of 14.17 g silver nitrate (0.0838 moles) in 200 ml water, and 100 g (0.419 moles) trans-4-(4-chlorophenyl)cyclohexane carboxylic acid were prepared. To this mixture acetonitrile 500 ml was added under stirring and heated to reflux. 80 g (0.506 moles) 1,4-naphthoquinone was then added. 239 g (1.048 moles) ammonium persulfate dissolved in 600 ml water was added drop-wise to the stirred solution and continued reflux for half an hour. The reaction solution was then cooled to 30-32° C. and extracted with methylene chloride. The organic layer was first washed with water, followed with 10% sodium carbonate aqueous solution, and further with water until neutral pH. The organic layer was distilled to eliminate methylene chloride, stirred in acetonitrile, and filtered. The solid obtained was crystallized from acetonitrile to obtain 29.8 g of the trans isomer of Formula II (20.3% yield). M.P. 147- 149° C. (uncorrected).
