3-Methylcyclohexene (CAS no.: ), which is known as , phenyl-, could be produced through the following synthetic routes.

A. 3-Methyl-2-cyclohexen-1-ol. A solution of 33.6 g. (0.305 mole) of 3-methyl-2-cyclohexen-1-one in 600 ml. of anhydrous diethyl ether is placed in a 2-l., three-necked, round-bottomed flask fitted with a mechanical stirrer, a reflux condenser attached to a source of dry nitrogen, and a pressure-equalizing dropping funnel. The solution is stirred and cooled in an ice bath while 471 ml. (0.0825 mole) of a 0.175 M solution of lithium aluminum hydride in ether is added dropwise. When the addition is complete the reaction mixture is stirred at 0° for another 15 minutes. Cooling and gentle stirring are continued while moist ether is added through the dropping funnel until gas is no longer evolved. The resulting slurry is filtered, and the filtrate is washed with saturated aqueous sodium chloride and dried over magnesium sulfate. Removal of ether on a water bath and distillation of the residue under reduced pressure provide 33.7 g. (98%) of 3-methyl-2-cyclohexen-1-ol, b.p. 94–95° (31 mm.).

B. Amalgamated . Zinc powder (206 g., 3.15 moles) is placed in a 1-l. beaker, covered with 250 ml. of 10% hydrochloric acid, and stirred for 2 minutes. The acid is then decanted and replaced by distilled water, the mixture is stirred, and the supernatant is decanted. Washing is continued in this way until the water is neutral to litmus. A warm solution of 40 g. (0.15 mole) of mercury(II) chloride in 250 ml. of distilled water is then poured onto the zinc, and the mixture is stirred gently for 10 minutes. After filtration, the powder is washed with 250 ml. of distilled water, five 250-ml. portions of 95% ethanol, and five 250-ml. portions of anhydrous ether. Drying under vacuum gives 196 g. of zinc amalgam.

C. 3-Methylcyclohexene. A 1-l., round-bottomed, three-necked flask equipped with a mechanical stirrer, a reflux condenser connected to a source of dry nitrogen, and a pressure-equalizing addition funnel is charged with 196 g. (3 moles) of dry amalgamated zinc powder, 22.4 g. (0.200 mole) of 3-methyl-2-cyclohexen-1-ol (CAS no ), and 280 ml. of anhydrous ether. The flask is placed in an ethanol–water–dry ice bath maintained at -15° throughout the reaction. The reaction mixture is stirred gently for 5 minutes, then stirred vigorously while 153 ml. (0.40 mole) of 2.6 M hydrogen chloride in anhydrous ether is added dropwise over 1.5 hours. When the addition is complete, stirring is continued for an additional 15 minutes, after which the reaction medium is neutral to moist litmus.

Decanting the reaction mixture separates residual zinc, which is washed thoroughly with two 200-ml. portions of ether. The ethereal solutions are combined, washed sequentially with two 50-ml. portions of water, 50 ml. of 10% aqueous sodium hydrogen carbonate, and two 50-ml. portions of saturated aqueous sodium chloride, and dried over magnesium sulfate. After filtration, ether is removed by careful distillation through a Dufton column at atmospheric pressure. When the residual solution is approximately 100 ml. in volume, it is transferred to a smaller apparatus and distilled slowly at atmospheric pressure. After a forerun of ether, 13.2–14.4 g. (68–75%) of 3-methylcyclohexene distils at 103–104°.