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Magnetic nonequivalences in 2,2,4-trimethylpentane-1,3-diol diisobutyrate and diacetate

✍ Scribed by Richard M. Fantazier

Publisher
John Wiley and Sons
Year
1973
Tongue
English
Weight
692 KB
Volume
5
Category
Article
ISSN
0749-1581

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✦ Synopsis

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.

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✍ Richard M. Fantazier 📂 Article 📅 1973 🏛 John Wiley and Sons 🌐 English ⚖ 492 KB

## Abstract The methylene protons in 2,2,4‐trimethylpentane‐1,3‐diol (**1**), its __1__‐isobutyrate (**2**) and __3__‐isobutyrate (**3**) monoesters, are magnetically nonequivalent with respect to chemical shift. Under the same experimental conditions, the chemical shift differences are 14·4 Hz, 46

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