New Aspects of the Chemistry of Quaternary Addition Reagents for the Electrocrystallisation of Zinc.
The introduction of quaternary pyridinium derivatives as brightening agents for the electrodeposition of zinc from alkaline electrolytes is one of the significant recent advances in this field. This work describes the brightening effect of quaternary pyridinium derivatives, with differences in structure, on the zine deposits obtained from alkaline cyanide and cyanide-free electrolytes. In addition chemical changes were found to be occurring in these solutions, which could be followed. using ultra-violet and nuclear magnetic resonance spectroscopy. Analysis of the ultra-violet data has enabled the kinetics of these reactions to be deduced and this together with relevant information from the literature, has led to the hypothesis that the new species are bimolecular ethers. A correlation of the ultra-violet and electroplating results, suggests that these bimolecular ethers may be the brightening agents and not the materials originally added...
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