[Mg].CC1CCCO1.[C:8]1([CH:15]([CH3:17])[CH3:16])[CH:13]=[CH:12][C:11]([CH3:14])=[CH:10][CH:9]=1.II.C([Mg]Cl)C.BrCCBr.C1(C)CCC(C(C)C)C(Cl)C1.[C:39](=[O:41])=[O:40]>>[CH:11]1([CH3:14])[CH2:12][CH2:13][CH:8]([CH:15]([CH3:17])[CH3:16])[CH:9]([C:39]([OH:41])=[O:40])[CH2:10]1Magnesium (15.6 g, 50 mesh), 2-methyl-tetrahydrofuran (103 g), para cymene (50 g), iodine (0.1 g), and ethyl magnesium chloride (4 cc) were added under nitrogen to a 1-liter flask equipped with agitation, addition funnel, off-set adaptor for thermometer, gas addition tube, and condenser. The mixture was stirred for 30 min. at 75° C., and then 1,2,-dibromo ethane (4 cc) was slowly added. p-Menth-3-yl chloride (134 g dissolved in para cymene) was then added at a rate of 33 g/hr (0.21 mole/hr). After approximately ½ of the p-menth-3-yl chloride was added, carbon dioxide was concurrently added by bubbling the carbon dioxide into the mixture at a rate of 7.8 g/hr (0.18 mole/hr), and at a temperature of 80° C. After all of the p-menth-3-yl chloride was added, the temperature was raised to 90° C. to complete carbonation. After carbonation was complete, the resultant mixture was hydrolyzed with aqueous hydrochloric acid having a concentration of 15%. VPC analysis showed a yield of 78.3% by weight of p-menthane-3-carboxylic acid.
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