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Studies of substituent effects by carbon‐13 NMR spectroscopy. VI —Application of multivariate data analysis to 13 C NMR chemical shifts of protonated chalcones and thiophene chalcone analogues
Author(s) -
Musumarra Giuseppe,
Carbone Domenica,
Johnels Dan,
Edlund Ulf
Publication year - 1986
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.1260240305
Subject(s) - chemistry , chalcone , substituent , protonation , carbon 13 nmr , thiophene , chemical shift , nuclear magnetic resonance spectroscopy , proton nmr , organic chemistry , spectroscopy , computational chemistry , physics , quantum mechanics , ion
The 13 C NMR chemical shifts of protonated chalcones and thiophene chalcone analogues were analysed by two multivariate data analysis methods, principal components analysis and partial least squares analysis. A general relaying effect of the carbenium centre was manifested by an increased sensitivity to substituent changes at positions conjugated to the charged position. The shift data in both series could be satisfactorily described by the 13 C NMR shifts of monosubstituted benzenes, as shown by partial least squares data analysis. This indicates a grouping of substituent effects into those of donors, acceptors, alkyls and halogens.