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Thermochemistry of phenols: experimental standard molar enthalpies of formation of 2-phenylphenol, 4-phenylphenol, 2,6-diphenylphenol, and 2,2′- and 4,4′-dihydroxybiphenyl

https://doi.org/10.1006/jcht.1997.0316Get rights and content

Abstract

The standard (p°=0.1 MPa) molar enthalpies of formation ΔfHm°(cr) at the temperatureT=298.15 K were measured by using combustion calorimetry of 2-phenylphenol, 4-phenylphenol, 2,6-diphenylphenol, 2,2′-dihydroxybiphenyl, and 4,4′-dihydroxybiphenyl. The standard molar enthalpies of sublimation ΔcrgHm° of the compounds were obtained from the temperature variation of the vapour pressure measured in a flow system. Molar enthalpies of fusion Δcr1Hm° of the compounds were measured by d.s.c. Values of the weak interactions (about 2 kJ·mol−1to 4 kJ·mol−1) of phenyl substituents with the hydroxyl group were derived from the enthalpies of formation in the gas phase.

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The experimental part of this work was done at the Institute of Organic Chemistry and Biochemistry, University of Freiburg, F.R.G. (E-mail: [email protected]).

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