NMR 1H spectra

The chemical shifts in NMR 1H spectra of the para-substituted propylbenzens by the general formula:  p-X-C6H4-CRR1CH2CH3 (where R, R1 = H, CH3) have been analyzed. The presence or absence of the aryl fragment influence on the methyl end-group was observed by the value of the basic spectral parameters – the chemical shifts of methyl protons (δСН3Н) in comparison with analogous data of corresponding alkanes. The specific criteria for identifying such effect were developed and validated.

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.