Reduction of 2,6-Dimethylcyclohexanone with Sodium Borohydride Revisited: A Correction on the Structural Assignments of the Products, and the Discovery of a Solvent Effect

In a previously published article in this Journal (Garner, C. M. J. Chem. Educ. 1993, 70, A310-A311), 2,6-dimethylcyclohexanone was reduced with sodium borohydride in methanol to form 2,6-dimethylcyclohexanol. Product assignment was done by GC, according to previous literature results (Wigfield, D. C.; Phelps, D. J. J. Am. Chem. Soc. 1974, 96, 543-549.). NMR analysis clearly showed the major component to be the cis-cis isomer rather than the trans-trans isomer, as claimed in the previous work.Changing the solvent from methanol to ethanol produced a different ratio of cis-cis to trans-trans than was reported in the original work. Therefore, a short series of solvents was investigated to determine if there was a solvent effect. The results indicate that as the size and bulk of the solvent increase, the proportion of the trans alcohol product increases.