Premium
Aryl carbon chemical shifts of methylbenzoic acids and methylbenzoate anions
Author(s) -
Guilleme Joaquin,
Diez Ernesto,
Bermejo Francisco J.
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230608
Subject(s) - chemistry , chemical shift , aryl , additive function , carboxylate , carbon fibers , aqueous solution , medicinal chemistry , twist , spectral line , computational chemistry , quantum chemical , stereochemistry , organic chemistry , molecule , mathematical analysis , alkyl , materials science , mathematics , composite number , composite material , geometry , physics , astronomy
The aryl carbon chemical shifts of methylbenzoic acids in CDCl 3 and methylbenzoate anions in aqueous NaOH solutions have been assigned. The shifts have been interpreted by means of a model based on the additivity of substituents which is similar to that previously developed for the analysis of the methyl chemical shifts. Corrective parameters included to take into account the interactions of adjacent substituents are found to be related to both the twist angle, θ, of the carboxyl or carboxylate substituents and the conformation of the methyl groups. The derived values of the twist angle are in closer agreement with x‐ray data than those estimated from UV spectra or from Cl‐PPP computations.