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Substituent effects of 1 H NMR parameters of chlorinated diphenyl ethers. A statistical approach
Author(s) -
Nevalainen Tapio,
Kolehmainen Erkki
Publication year - 1994
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260320809
Subject(s) - chemistry , chemical shift , substituent , steric effects , intramolecular force , coupling constant , chlorine , computational chemistry , chlorine atom , proton nmr , nmr spectra database , carbon 13 nmr , proton affinity , ring (chemistry) , spectral line , stereochemistry , medicinal chemistry , organic chemistry , protonation , ion , physics , particle physics , astronomy
The 1 H NMR spectra of 64 polychlorinated diphenyl ethers (PCDEs) were measured and assigned. Multiple linear regression analysis was used to estimate the effects of chlorine atoms on the 1 H NMR chemical shifts and coupling constants. The ‘simple sum rules’ were found to be inadequate for the prediction of 1 H NMR chemical shifts of PCDEs. Therefore, corrective terms of two chlorine atoms were taken into account. The most important effects on chemical shifts were shown to be the steric interactions of two adjacent chlorine atoms and the intramolecular ring current effect observed in the ortho ‐proton of tri‐ ortho ‐substituted PCDEs. The substituent effects on J (HH) coupling constants were found to be approximately additive. An interannular coupling between ortho ‐protons [ 6 J (HH) = 0.05–0.15 Hz] of adjacent rings was observed.