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Principal component analysis in studies of substituent-induced chemical shifts of 1,4-disubstituted benzenes

✍ Scribed by Eduardo L. Canto; Ljubica Tasic; Roy E. Bruns; Roberto Rittner

Publisher
John Wiley and Sons
Year
2001
Tongue
English
Weight
120 KB
Volume
39
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Chemometric analyses of 1,4‐disubstituted benzene aromatic carbon atom NMR chemical shifts, bearing 14 substituents (X) within a complete series involving the same substituents as fixed groups (Y), are reported. The substituent effects of (i) strong electron donors (NMe~2~, NH~2~ and OMe), (ii) halogens (F, Cl and Br), (iii) electron acceptors (CF~3~, CN and NO~2~), (iv) acceptors of the carbonyl type [C(O)OEt, C(O)Me and CHO] and (v) neutral groups (H and Me) were studied using principal component analysis (PCA). The charge alterations (Δ__q__) induced by introducing a substituent X at C‐1 were also analyzed by the means of PCA of data obtained from theoretical calculations (AM1 method). The correlations among the substituent chemical shifts (SCS) and among the charge alterations (Δ__q__) and the dependence of SCS on charge alterations were analyzed by regression analyses applied to the scores of the first principal components (PC1) obtained in the PCA of the SCS and Δ__q__ values. Copyright © 2001 John Wiley & Sons, Ltd.

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