Determination of Components in Phenol Mixtures by Nuclear Magnetic Resonance.

Abstract

Many mixtures of phenols in hexamethylphosphoramide were found to give NMR spectra containing a well resolved hydroxyl peak for each component. These peaks occur in the region 8 to 13 p.p.m. and are free from interference due to aromatic proton absorption. The chemical shift of a particular phenol is not affected

Understanding of Assembly Phenomena by Aromatic−Aromatic Interactions: Benzene Dimer and the Substituted Systems

“…These can be contrasted with the corresponding values of the T conformers which are −1.08/ −0.55/−0.44/(0)/−0.21/−0.18/−0.04 kcal/mol with respect to the T conformer of the benzene dimer. The stability of T conformers reflects the Hammett constants (σ p for NH 2 /OH/CH 3 /H/F/CN/NO 2 is −0.66/−0.37/−0.17/0/+0.06/+0.66/+0.78) ), the complexes with an electron withdrawing/donating group are more/less stable than the benzene dimer.…”

Integrated Intensities of Absorption Bands in Infrared Spectroscopy

“…A correlation between infrared intensities and NMR and PMR chemical shifts may be anticipated and such correlations have been reported [200]. The correlation of both infrared intensities [7,8] and NMR chemical shifts with Hammett and Taft reactivity parameters [201] implies that both types of probes sense similar perturbations of electronic structure, although by completely different mechanisms (dipole-moment variations and changes in nuclear spin frequencies).…”

Nuclear magnetic resonance spectrometry

“…Additivity rules are given or extended for alkyl benzenes (2082), methyl benzenes (1 733) phenolic compounds (1 15), 4,6disubstituted o-cresols (1152), vinylic protons (1605), angular methyls in steroids (various solvent systems often are considered) (372,645,644,2168,444,2167,160,87), and methylene groups adjacent to C=C (2011). Correlation between Hammett u constants for aromatic ring substituents and shifts of protons on or near the ring are reported for phenolic OH (2056,502), OH of substituted benzoic acids (1154), aromatic aldoximes (1619), 3-substituted 1,2,4-triazoles (715), protons of a-substituted pyridines (1621), aromatic aldehyde protons (75), toluenes, acetophenones, and thioanisoles (1388), some substituted styrenes (536), vinyl protons of heteroaryl acrylics (1086), N H of substituted anilines (2203)) Nmethyl of dimethyl anilines (1696), and furanes (1604,1477). Correlation between Hammett u constants for aromatic ring substituents and shifts of protons on or near the ring are reported for phenolic OH (2056,502), OH of substituted benzoic acids (1154), aromatic aldoximes (1619), 3-substituted 1,2,4-triazoles (715), protons of a-substituted pyridines (1621), aromatic aldehyde protons (75), toluenes, acetophenones, and thioanisoles (1388), some substituted styrenes (536), vinyl protons of heteroaryl acrylics (1086), N H of substituted anilines (2203)) Nmethyl of dimethyl anilines (1696), and furanes (1604,1477).…”

“…Components in mixtures of phenols can be analyzed by their OH peak positions in properly prepared hexamethylphosphoramide, where the shifts are down field from the aromatic proton region (502). Thiols may be identified more readily, or their spectra simplified, by in situ treatment with reactive isocyanates (309).…”