Interaction between phenol and electron donors in cyclohexane and carbon tetrachloride

Abstract

Association constants, k_c, for the process phenol + electron donor ⇌ complex have been determined from absorbance measurements at a predetermined wavelength in the u.v. region for a series of solutions of phenol in cyclohexane–donor and carbon tetrachloride–donor mixtures of varying composition. Electron donors used are classified as ether- or alcohol-type and consist of 1,2-dimethoxyethane, tetrahydrofuran, dioxan, diethyl ether, di-isopropyl ether, di-n-butyl ether, methanol, ethanol, n-butanol, propan-2-ol, isoamyl alcohol, t-butyl alcohol, and dimethylformamide. It is found that (i)K_c is greater in cyclohexane than in carbon tetrachloride solution, (ii)K_c increases with increase in donor E_T value, and in the case of the ethers with Δν_D the shift in the O–D stretching frequency of methan[²H]ol, defined as ν_D(benzene)–ν_D(ether), and (iii) variation in K_c arises principally from changes in the standard entropy of association, ΔS^⊖.