A. Ethyl cis- and trans-2-phenylcyclopropanecarboxylate. Xylene (500 ml., (Note 1)) is heated to reflux in a 2-l. flask equipped with a mechanical stirrer, dropping funnel, and reflux condenser. A solution of 179 g. (1.57 moles) of ethyl diazoacetate [Org. Synth., Coll. Vol. 4, 424 (1963)] (Note 2) and 163 g. (1.57 moles) of styrene (Note 3) is placed in the dropping funnel and added dropwise to the refluxing, stirred xylene over a period of 90 minutes. After addition is complete, the solution is stirred and heated at the reflux temperature for an additional 90 minutes (Note 4). Xylene is removed under reduced pressure, and the residual red oil is distilled through a short Vigreux column. The fraction boiling at 85–93° (0.5 mm.) is collected, yielding 155 g. (52%) of colorless product, n_D26 1.5150, n_D20 1.5166 (Note 5) and (Note 6).

B. cis-2-Phenylcyclopropanecarboxylic acid. A 1-l., three-necked flask equipped with a dropping funnel, stirrer, and a short Vigreux column (Note 7), to which is attached a partial take-off distilling head with reflux condenser, is charged with 155 g. (0.816 mole) of ethyl cis- and trans-2-phenylcyclopropanecarboxylate, 200 ml. of ethanol, 65 ml. of water, and 24.5 g. (0.612 mole) of sodium hydroxide pellets (Note 8). The mixture is heated at the reflux temperature for 5 hours during which time 200 ml. of ethanol is slowly distilled and replaced by an equal volume of water added through the dropping funnel. Heating is discontinued, 250 ml. of water and 150 ml. of benzene are added, and the mixture is stirred for 2–3 minutes. The layers are separated, and the aqueous layer is washed with two 50-ml. portions of benzene (Note 9).

The benzene extracts are placed in the apparatus used above, and 130 ml. of water and 13 g. (0.32 mole) of sodium hydroxide pellets are added. Benzene (200 ml.) is distilled and then the 200 ml. of ethanol obtained in the initial hydrolysis is added. The reflux-distillation process is continued for 5 hours, during which time 250 ml. of distillate is obtained. The mixture is cooled, and 65 ml. of benzene and 30 ml. of concentrated hydrochloric acid are added. The layers are separated, and the aqueous solution is washed twice with 35-ml. portions of benzene. The combined benzene extracts are concentrated and dried by distillation of 90 ml. of benzene. The hot concentrate is decanted from a trace of salt, 70 ml. of petroleum ether is added, and the resulting solution is stored overnight at 0°. Filtration of the solid from the cold petroleum ether solution and washing with a small volume of cold 50:50 benzene–petroleum ether yields 19.5–23.8 g. (14.6-20.7% based on the mixed ester used, or 38–46.4% based on the cis ester, (Note 10)) of cis-2-phenylcyclopropanecarboxylic acid, m.p. 106–109° (Note 11). An additional 2–3 g. of the cis acid may be obtained by concentrating the mother liquors to low volume, adding petroleum ether, and chilling the resulting solution for several days.