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In a previously published article in this Journal (1), 2,6-dimethylcyclohexanone was reduced with sodium borohydride in methanol to form 2,6-dimethylcyclohexanol (see Fig. 1). This experiment was done on the microscale, and product assignment was done by GC, according to previous literature results (2).
When this experiment was modified for the semimicroscale, the GC conditions needed to separate the three alcohol products were investigated. With a Carbowax column, the largest peak came out first, whereas with an SE-30 column, the largest peak came out second. Since order of elution varied with column polarity, a more definitive method was needed to determine the structure of the major product. An NMR analysis of these three alcohols had previously been published (3). The chemical shift of the hydrogen alpha to the OH for each of the three isomers is different enough so that proton NMR can resolve them. NMR analysis of the product mixture clearly showed the major component to be the cis-cis isomer, 1 (broad singlet at 3.50 ppm), rather than the trans-trans isomer, 2 (triplet, J = 9 Hz, at...