New experimental results on oscillatory aerial oxidation of aldehydes

Abstract

Some new experimental results on the oscillatory aerial oxidation of acetaldehyde, propionaldehyde and benzaldehyde in 90% acetic acid containing cobalt (II) acetate and sodium bromide are reported. It has been observed that benzaldehyde can be replaced by acetaldehyde or propionaldehyde but not by formaldehyde. Oscillations are not observed when cobalt (II) acetat, is replaced by cobalt nitrate, cuprous chloride, cupric acetate and manganese acetate. Bromate ion or liquid bromine. However, can replace sodium bromide. Certain additives, viz., CCI₄, Hg²⁺ ions, KI, I₂, phenol. aniline, 1,10-phenanthroline, ethylenediamine, acetylacetone and hydroquinone quench the oscillations. Addition of sodium chloride to the oscillatory system yields different types of colour oscillations (blue⇌olive green) instead of pink to brown. A semi-batch reactor has been used to study oscillatory system containing acetaldehyde under controlled conditions of temperature. oxygen flow-rate and the reactant concentrations.