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Issue 1, 1999
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Substituent effects on the benzene ring. Prediction of the thermochemical properties of alkyl substituted hydroquinones

Abstract

The standard molar enthalpies of formation ΔfHm°(cr) at 298.15 K for hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and 2,3-dicyanohydroquinone were measured by combustion calorimetry. The standard molar enthalpies of sublimation of 2-methylhydroquinone, 2-tert-butylhydroquinone, and 2,5-di-tert-butylhydroquinone were obtained from the temperature dependence of the vapour pressure measured in a flow system. Molar enthalpies of fusion ΔcrlHm° of the latter compounds were measured by differential scanning calorimetry (DSC). Resulting values of ΔfHm°(g) were obtained at 298.15 K and were used to derive the strain enthalpies of alkylhydroquinones. The intramolecular interactions of the substituents are discussed in terms of the deviations of ΔfHm°(g) from the group additivity rules. No peculiarities in the interaction energies among the alkyl and the hydroxy groups in the ortho- and meta-positions of alkylhydroquinones were detected in comparison with alkyl-substituted phenols. Thus, no new parameters are needed for the prediction of the ΔfHm°(g) of similar shaped alkylhydroquinones by using the group-additive procedure.

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Supplementary files


Article type: Paper
DOI: 10.1039/A806706F
Phys. Chem. Chem. Phys., 1999,1, 127-131

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    Substituent effects on the benzene ring. Prediction of the thermochemical properties of alkyl substituted hydroquinones

    S. P. Verevkin, Phys. Chem. Chem. Phys., 1999, 1, 127
    DOI: 10.1039/A806706F

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