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Quantitative studies of hydrogen bonding in ortho-substituted phenols using proton magnetic resonance.

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Title: Quantitative studies of hydrogen bonding in ortho-substituted phenols using proton magnetic resonance.
Author: Allan, Ernest Albert
Degree: Master of Science - MSc
Program: Chemistry
Copyright Date: 1963
Subject Keywords Phenols;Nuclear magnetic resonance
Issue Date: 2011-10-27
Publisher University of British Columbia
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Abstract: The chemical shift of protons in intramolecular hydrogen bonds has been measured in 41 ortho substituted phenol type compounds. The change in chemical shift " ΔσOH " on formation of these hydrogen bonds is taken as the difference between the infinite dilution chemical shift of the parent phenol compound in CCl₄ solution and the chemical shift measured for the proton in the intramolecular hydrogen bond. This change in chemical shift is correlated with the corresponding frequency shift " ΔνOH " in the -OH stretching region of the infra-red spectrum. The dilution chemical shift for the -OH proton in the o-halophenols has been investigated over a concentration range 1-5 mole % in CS₂ and a temperature region -53 to 107°C Using the infinite dilution shift values, the equilibrium constants of the cis-trans conversion were obtained. Values for δCIS, the chemical shift of the completely hydrogen bonded form; δ TRANS, the chemical shift of the unbonded form, and ΔH , the enthalpy of formation of the hydrogen bond, were also calculated. From these results a value for ΔH, the enthalpy of formation for the dimer was calculated, assuming that the major dimer species in solution was formed from the combination of a cis and trans bonded form. Temperature studies of the change in chemical shift of the -OH proton for 2,1,6-trihalosubstituted phenols is also reported. The temperature range in this case was 0°C to 111°0.
Affiliation: Science, Faculty of
URI: http://hdl.handle.net/2429/38352
Scholarly Level: Graduate

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