Reaction mechanism of some benzene sulfonamide and saccharin derivatives during nickel electrodeposition in Watts-type electrolyte

The reaction mechanism of additives was investigated in Ni eletrolytes by determination of their consumption in different cathodic processes and by accumulation rates of cathodic reaction products. The methyl group of o- and p-toluene sulfonamides and N-methylsaccharin increased the rates of additives consumption mainly by the acceleration of desulfuration reaction. The consumption rates of the above additives and the rates of desulfuration reactions decreased with increase in temperature of the electrolyte. The amino group in the aromatic cycle of benzene sulfonamide increased interaction between additives and the cathode. Incorporation of organic compounds into electrodeposits was observed, in addition to desulfuration. Increase in temperature increased the aminobenzene sulfonamides consumption. The triple bond in the side chain of N-(2-butyn-4-ol)saccharin made the reaction mechanism quite complicated. At least 15 cathodic reactions took place in this process. Additive consumption increased with temperature.