Effects of the intramolecular hydrogen bond on intermolecular hydrogen bonding in hydroxybenzene-ether systems

Abstract

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.

Intermolecular Hydrogen Bonding Modulates O‐H Photodissociation in Molecular Aggregates of a Catechol Derivative

“…1b) features two narrow and intense absorption bands at 3576 and 3624 cm À1 , which are assigned to the intramolecularly hydrogen-bonded ("b") and free ("f") O-H local stretching modes (Fig. 1e), respectively, based on catechol studies (34)(35)(36). CAM-B3LYP calculations on the monomer support this assignment, giving frequencies of 3826 and 3892 cm À1 for the b and f modes.…”

Effects of Multiple OH/SH Substitution on the H‐Bonding/Stability versus Aromaticity of Benzene Rings: From Computational Insights

“…Here in this work, four types of IHBs: (i) O−H⋅⋅⋅O (ii) O−H⋅⋅⋅S (iii) S−H⋅⋅⋅O, and (iv) S−H⋅⋅⋅S have been observed in the framework of both the DFT and ab initio approaches. At the first glance, using the QTAIM tool, only three kinds of IHBs such as O−H⋅⋅⋅S, S−H⋅⋅⋅O, and S−H⋅⋅⋅S were detected (small sphere is shown in light blue colour) while the O−H⋅⋅⋅O type interaction(s) was/were absent [see Figures 1 ( 1 a ), 4 ( 4 a and 4 b ), 6 ( 6 a and 6 b , and 6 c ) indicated by light blue dotted colour for the sake of convenience], however, several reports on the existence of the O−H⋅⋅⋅O IHB(s) in the H‐bonded aromatic systems such as 1,2‐benzenediol, 1,2,3‐benzenetriol, and their related systems, are available in the literature [67–70] …”

Effects of Intra- and Intermolecular Hydrogen Bonding on O–H Bond Photodissociation Pathways of a Catechol Derivative

“…The spectra are presented as apparent extinction, which is calculated using ε apparent = A /( lc ), where A is the measured absorbance, l is the sample path length, and c is the initial concentration of 4-tBuC. Two narrow bands are seen in the 0% Et 2 O sample at 3624 and 3577 cm –1 , which correspond to the free O–H (f) and intramolecularly bonded O–H (b) modes, respectively. ,− For the 5% Et 2 O sample, the f band at 3624 cm –1 almost disappears, and the b band at 3577 cm –1 redshifts to 3562 cm –1 , which we label b′. Additionally, a new broad band appears at 3294 cm –1 with a shoulder at 3408 cm –1 .…”

“…Similar equilibria were discussed previously for unsubstituted catechol in carbon tetrachloride solution. 20,21 At low Et 2 O concentrations, the 1:1 complex dominates, in which 4-tBuC retains an intramolecular hydrogen bond while donating an intermolecular hydrogen bond to Et 2 O (f-solvated structure in Scheme 1). The bsolvated form of the 1:1 complex (Scheme S1) is not observed in any significant concentration.…”