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Magnetic nonequivalences in 2,2,4‐trimethylpentane‐1,3‐diol diisobutyrate and diacetate
Author(s) -
Fantazier Richard M.
Publication year - 1973
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270050207
Subject(s) - geminal , moiety , methylene , chemistry , intramolecular force , diol , solvent , steric effects , stereochemistry , carboxylate , solvent effects , medicinal chemistry , polymer chemistry , organic 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.