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Correlation of carbon‐13 substituent‐induced chemical shifts: Meta ‐ and para ‐substituted methyl benzoates
Author(s) -
Buděšńský Miloš,
Exner Otto
Publication year - 1989
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.1260270612
Subject(s) - substituent , chemistry , benzoates , principal component analysis , carbon fibers , chemical shift , linear correlation , medicinal chemistry , organic chemistry , computational chemistry , stereochemistry , mathematics , composite number , statistics , algorithm
Carbon‐13 NMR spectra are reported for 69 substituted methyl benzoates in deuteriochloroform or in its mixture with dimethyl sulphoxide‐ d 6 . The substituent‐induced chemical shifts (SCS) of the CO carbon correlate poorly with dual substituent parameters (DSP) in all possible modifications, and for meta derivatives in particular this correlation is both overpara meterized and imprecise. A much better correlation was obtained with parameters (designated B m , B p and C p ) derived previously by principal component analysis (PCA) from a larger set. The SCS of the CH 3 carbon correlate very well with the original simple Hammett equation, and no DSP treatment is needed. The clustering of substituents is not consequential in such a large set.