Electrochemical Oxidation of 4-Morpholinoaniline in Nonaqueous Solvents

Abstract

Electrochemical oxidation of 4-morpholinoaniline (4MA) in six nonaqueous solvents was carried out using cyclic voltammetry technique. Two one-electron transfer couples were observed with a half-wave potential separation ( E 1/2 ) which is consistent with the donor number of solvents. In these solvents, in scan rates (0.1-1 Vs −1 ), the first oxidation step of 4-morpholinoaniline was found to be diffusion controlled with chemically reversible process. Significant differences in the chemical reversibility were observed for the second oxidation step. In donor solvents such as DMSO, DMF and THF, the oxidation of 4MA •+ to the dication (4MA 2+ ) is coupled with chemical follow-up reactions. Also the solvent effects on the heterogeneous electron exchange of 4MA to radical cation (4MA •+ ) have been studied in nonaqueous solvents. In addition, the effect of the physical and chemical properties of the solvent on the electrochemical behavior of the 4MA/4MA •+ couple has been examined. Values of the heterogeneous electron transfer rate constants (k s ) were determined through cyclic voltammetry by applying digital simulation method. It has been shown that the dynamics of solvent reorientation strongly affects the heterogeneous electron transfer rate in the studied case. An almost linear relationship between ln k s and ln τ L , the longitudinal relaxation time of a given solvent has been found.

Electrochemical study of Alamar Blue (resazurin) in aqueous solutions and room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate at a glassy carbon electrode

“…It is well known that, the reduction mechanism of an organic compound changes from the one two-electron step in a protic to the two one-electron steps in an aprotic environment. 26,27 So, it can be concluded that, the two-electron reduction of 1 to 2 in aqueous solutions (Scheme 1), changes to the two successive one-electron transfer steps in [C4mim][BF4] (Scheme 7).…”

Solvent effects on electrosynthesis, morphological and electrochromic properties of a nitrogen analog of PEDOT

“…On the other hand, despite the fact that significant efforts are devoted mainly to structural designing, the physical and chemical properties of CPs are also highly dependent on the polymerization conditions involving applied potentials, solvents, supporting electrolytes, current density, temperature and pH, as well as the method of electropolymerization. [18][19][20] For typical conducting polymers including polypyrrole, [21][22][23] polythiophene (inclusive of PEDOT) [24][25][26][27] and polyaniline, [28][29][30] effects of electropolymerization conditions on polymer films based on monomers have been substantially studied. It was reported that a small supporting electrolyte was easily dispersed in the polymer films to improve doping and contrast, and thus the electrochromic performances.…”

Mechanistic study of electrochemical oxidation of 2,5-diethoxy-4-morpholinoaniline in aqueous solutions: hydrolysis, trimerization, and hydroxylation processes

“…It is known that cyclic voltammetry is a powerful technique for investigation of electrochemical reactions that are coupled with chemical reactions [13,14]. Electrochemical studies of amines were performed at various conditions such as aqueous and nonaqueous solvent or at various pHs [15][16][17][18][19][20][21]. Electrochemical oxidation mechanism of aromatic amines is quite complex, and leads to a variety of products depending on their structure and electrolysis conditions [22,23].…”