Effect of Substituent Geometrical Parameters on the Chemical Shifts of Ortho- and Meta-Protones in 1H NMR-Spectra of Monosubstituted Benzenes

Spectral (NMR 1H) parameters of phenyl ring protons in 26 monosubstituted benzenes C6H5-Y, including benzene, have been investigated. The values of ortho-, meta- and para-protons chemical shifts, as well as differences between the values of mentioned protons absorption have been analyzed by analytical and graphical ways. The concept of ideal plots for three types of phenyl protons and substituent “voluminosity” has been introduced. The dependence of voluminosity on substituent chemical structure and influence of voluminosity on the chemical shift of ortho-protons signals were shown. The plots of ortho-protons chemical shifts versus Brown constants have the high (99 % and more) correlation coefficient.