R. Fantazier
Feb 1, 1973
Citations
0
Influential Citations
3
Citations
Journal
Magnetic Resonance in Chemistry
Abstract
2,2,4-Trimethylpentane-1,3-diol diisobutyrate (1) and diacetate (2) exhibit magnetic nonequivalence for both sets of geminal-dimethyl groups adjacent to the asymmetric center, and nonequivalence of the methylene protons three bonds removed. Solvent and temperature studies indicate that one geminal-dimethyl moiety is affected only by intramolecular influences, while the other is also subject to solvent effects. The behavior is rationalized in terms of a preferred conformation in which steric effects prevent the interaction of one moiety with solvent. An inverse temperature dependence for methyl nonequivalence is observed for 2 and an absence of a temperature dependence is noted for 1. The unusually large methylene nonequivalences, 23 Hz in 1 and 34 Hz in 2, are attributed to the proximity of an ester carboxylate.