Utilisation de la méthode d'autocorrélation modifiée pour étudier des relations structure–déplacement chimique 13C pour des alcanes

Abstract

Abstract Use of a modified autocorrelation method to study 13C chemical shifts-chemical structure relationships for alkanes. The concept of the multifunctional autocorrelation method governing global description of molecules was modified, in order to generate new atomic environments. Such atomic environments allow the generation of atomic descriptors by means of a modified autocorrelation method. The principle of this approach is explained through a case study dealing with the design of a model allowing the simulation of the carbon-13 nuclear magnetic spectra for alkanes. The data set contains 243 values of chemical shifts. Carbon atoms in alkanes are described by using as structural descriptor a vector corresponding to only four components of the multifunctional autocorrelation method. The established model allows us the prediction of the 13C chemical shift with high success. Results obtained by means of multiple regression analysis was less satisfying than those obtained using neural network approach. The quality of the neural network model was evaluated by means of the Cross validation technique, with a mean error between δexp and δcalc of 0.60 ppm.