# Electrochemical reduction of 4-(2′-thienyl)quinazoline in acid solutions☆

TL;DR: In this paper, the electrochemical behavior of 4(2′-thienyl)quinazoline (4TQ) was studied in acid solutions of varying ionic strengths using polarography, cyclic voltammetry and controlled-potential electrolysis.

Abstract: The electrochemical behaviour of 4(2′-thienyl)quinazoline (4-TQ) was studied in acid solutions of varying ionic strengths using polarography, cyclic voltammetry and controlled-potential electrolysis. 4-TQ is reduced in two single electron steps to give the dihydro-4-TQ product. The two polarographic waves were found to be diffusion-controlled, the first wave being reversible and the second wave irreversible. On the basis of the results obtained, a mechanism is suggested for 4-TQ reduction in which a dimerization reaction goes in parallel with the electron-transfer step.

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TL;DR: In this paper, an equation for the current-time relationship when a linear potential sweep is applied to an electrode has been derived, where is a constant dependent on the potential interval over which the integration is carried out, but independent of sweep rate, C the concentration of the species undergoing reaction, A the electrode area, and ν the time rate of change of the linear potential sweeping.

Abstract: Integration of the equation for the current‐time relationship when a linear potential sweep is applied to an electrode has led to an equation for the number of coulombs passed, , where is a constant dependent on the potential interval over which the integration is carried out, but independent of sweep rate, C the concentration of the species undergoing reaction, A the electrode area, and ν the time rate of change of the linear potential sweep. A procedure to distinguish between coulombs due to diffusing and nondiffusing reactants is given. The derived relationships are verified experimentally. Separation of the coulombs due to the reduction of ferric iron and platinum oxide under conditions where both reactions take place concomitantly is described. In the iodide‐iodine‐triiodide system, it is concluded that iodine, rather than triiodide, is the adsorbed species.

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TL;DR: In this article, the electronic absorption spectra of Wurster's cations in ethanol were studied by considering the symmetry properties of the singly excited electronic spectrum of the corresponding parent molecules, and it was confirmed that the monomer and dimer are in equilibrium in the solution at low temperature.

Abstract: The dimerization of p‐benzosemiquinone anion and Wurster's cations in ethanol has been studied by the electronic absorption spectra of these radicals formed by ultraviolet irradiation and chemical oxidation of the corresponding parent molecules. The ion radicals studied are p‐benzosemiquinone anion (SQ−), p‐phenylenediamine cation (PD+), N,N‐dimethyl‐p‐phenylenediamine cation (DMPD+, and N,N,N',N'‐tetramethyl‐p‐phenylenediamine cation (TMPD+). With an ethanol solution of p‐phenylenediamine bromide (PD+Br−), the concentration dependence of the two absorption maxima at 4650 and 6050 A (corresponding to the monomer and dimer, respectively) were studied quantitatively. It has been confirmed that the monomer and dimer are in equilibrium in the solution at low temperature. The equilibrium constants were found to be 2200 and 4400 liters mole−1 at − 72° and − 77°C, respectively. The electronic absorption bands of these dimers were interpreted by considering the symmetry properties of the singly excited electronic...

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