Publication costs assisted by Lebanon Valley CollegeThe hydrogen bonding of phenol, guaiacol, and catechol to the electron pair donors, dimethyl sulfoxide, tetrahydrofuran, and di-nbutyl sulfide, was studied in CCU solution at various temperatures by monitoring the hydroxyl stretching frequency at 3 µ. Only dimethyl sulfoxide was found to disrupt the intramolecular hydrogen bond of guaiacol. The intramolecular bond strength for guaiacol was found to be -3.3 kcal mol-1. All donors disrupt the intramolecular bond in catechol with consequent formation of hydrogen bonded complexes containing one and two donor molecules. The frequency shifts and enthalpy changes for the formation of the monodonor complex with catechol are larger than the corresponding properties for the phenol complex and reflect the influence of the intramolecular hydrogen bond on intermolecular hydrogen bonding.

Publication costs assisted by Lebanon Valley CollegeThe hydrogen bonding of phenol, catechol, guaiacol, and pyrogallol in diethyl ether-carbon tetrachloride solutions was studied over the temperature range 20-50" by monitoring the hydroxyl stretching frequency at about 3 p. The intramolecular hydrogen bond in guaiacol was not disrupted by association with diethyl ether. Equilibrium constants and enthalpy and entropy changes for the other systems were calculated. The intramolecular bond in catechol and pyrogallol is disrupted and both compounds form complexes containing one and two ether molecules, The frequency shift, enthalpy change, and equilibrium constant for the formation of the monoether complex with catechol and pyrogallol are larger than the corresponding properties for the phenol complex and reflect the influence of the intramolecular hydrogen bond on intermolecular hydrogen bonding. IntroductionThe study of the influence of the intramolecular hydrogen bond on hydrogen bonded properties has been largely limited to effects on ionization constants. Various investigators1.2 have reported abnormally large first ionization constants and abnormally small second ionization constants for dibasic acids which have intramolecular hydrogen bonding capability. If the intramolecular bond in such compounds as catechol and pyrogallol acts to increase the first ionization constant, the increased acidity of the hydrogen of the free hydroxyl group should be reflected in the thermodynamics of the intermolecular association of this hydroxyl with diethyl ether. A comparison of the thermodynamics of the phenol-ether complex with those of the catechol and pyrogallol ether complexes will thus allow a determination of the extent of the influence of the intramolecular bond on intermolecular hydrogen bonding.

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