Preparation of Coumarin Derivatives and their Evaluation as Additives for Nickel Plating Solutions

Abstract

SummaryAnalysis of the behaviour of coumarin and its breakdown products suggested that coumarino-7, 8-α-pyrone might be a levelling agent with less deleterious effects on the deposit. The compound was made, and shown to be sparingly soluble in Watts nickel plating solution and to exhibit moderate levelling power. It slightly reduced internal stress while the plate remained ductile and semi-bright. These properties were maintained over a longer period of use than was possible with a coumarin bath but the levelling power of the pyrone fell, with time, to a negligible value. It is concluded that unfavourable adsorption of the cathodic reduction product probably persists with this derivative of coumarin.