5.
Tasic L., Rittner R., Ferreira M. M. C., “a-Substituint Effects on NMR Chemical Shifs. Chemometric Approach”. Angra dos Reis, RJ, Brasil, 04-08/05/1999: VII Encontro de Usuários de Ressonância Magnética Nuclear [The VII Meeting of the Users of Nuclear Magnetic Resonance], An. Ressonância Magn. Nucl., 6, 107-114 (1999). Poster.
[Article. More information about the meeting see at Notes.]

Abstract (provisory).
The ¹³C and ¹H NMR a-substitution effects of twelve substituents of (-H, -F, -Cl, -Br, -OMe, -OEt, -SMe, -SEt, -SMe₂, -NEt₂, -Me, -Et) in four classes of a-substituted organic compounds (acetones, acetic acids, methyl acetates, 2-methy propenes) were studied by means of chemometric methods Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), the K-th Nearest Neighbor (KNN) and Soft Independing Modeling of Class Analogy (SIMCA) applied to 18 molecular parameters calculated at Hartree-Fock 6-31G(d,p) level and 6 parameters determined experimentally. The classification methods (PCA, HCA) showed that the NMR chemical shifts (the most important are those for a-H and a-C atoms) are mainly related to parameters accounting for inductive effects (depending on the nature of heteroatoms). The pattern recognition methods (KNN, SIMCA) showed efficient in classification of samples that belong to the investigated groups. Similar trends in properties of samples from the same class indicate that other possible samples from the same group have similar and predictable properties.

Keywords.
a-Substitution Effects; Chemometrics.

Keywords Plus.