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Correlation of carbon‐13 substituent‐induced chemical shifts revisited: Meta ‐ and para ‐substituted benzonitriles
Author(s) -
Exner Otto,
Buděšínský Miloš
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.1260270106
Subject(s) - substituent , chemistry , chemical shift , benzene , principal component analysis , carbon fibers , carbon 13 nmr , benzene derivatives , spectral line , series (stratigraphy) , computational chemistry , medicinal chemistry , organic chemistry , stereochemistry , chemical synthesis , materials science , artificial intelligence , composite number , computer science , composite material , paleontology , biochemistry , physics , astronomy , in vitro , biology
Abstract Carbon‐13 NMR spectra are reported for 63 substituted benzonitriles in deuteriochloroform or in its mixture with dimethyl sulphoxide‐ d 6 . The substituent‐induced chemical shifts (SCS) of the CN carbon correlate well with dual substituent parameters (DSP) in the para series but poorly in the meta series, whichever parameters are used. The DSP treatment was found to be inferior to principal component analysis (PCA), using as a probe 29 sets of literature data on α,β‐unsaturated benzene derivatives. Whereas one component is sufficient for meta derivatives, two terms are needed for para derivatives, which are different for the α‐ and β‐positions. The constants derived by PCA could be in principle used to predict further SCS, but their scope must be still explored.