Benzaldehyde and its derivatives are used as food supplements. These substances can be used mainly as flavorings or as antioxidants. Besides, peroxynitrite, an oxidizing agent, could be formed in canned food. Both species could react between them. The present article has focused on the kinetic study of the oxidation of aldehydes by peroxynitrite. A reaction mechanism that justifies all the experimental results is proposed. This mechanism, in acidic media, passes through three competitive pathways: (a) a radical attack that produces benzoic acid. (b) peracid oxidation, and (c) a nucleophilic attack of peroxynitrous acid over aldehyde to form an intermediate, X, that produces benzoic acid, or, through a Cannizzaro-type reaction, benzoic acid and benzyl alcohol. All rate constants involved in the third pathway (c) have been calculated. These results have never been described in the literature in acid media. A pH effect was analyzed.

Advances in science and technology have improved the quality of life but have also contributed to environmental pollution through additives like parabens, commonly used as preservatives in personal care products. This study investigates the degradation of a series of parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) in aqueous-phase solution initiated by peroxynitrous acid (HOONO), an oxidant present in environmental waters. A stopped flow system was employed to follow this oxidation reaction. A reaction mechanism, considering experimental variables, such as pH, temperature, ionic strength, radical scavengers, and reaction products detected, was proposed. This mechanism involves two competitive pathways: a radical attack producing hydroquinone and quinone and a nucleophilic attack by HOONO yielding p-hydroxybenzoic acid, a less ecotoxic compound than parabens. The acidic equilibrium constants of the carbonyl group of parabens and the rate constants for the nucleophilic attack of HOONO on parabens were experimentally determined. Additionally, a structure–reactivity correlation analysis (QSAR) through the Taft equation was applied for the determined equilibrium and nucleophilic attack rate constants. The derived QSAR can be applied to other water-soluble parabens.

Benzaldehyde and its derivatives are used as food supplements, due to their properties as anti-oxidants and mainly as organoleptic substances. The degradation of these aldehydes produces benzoic acid and benzyl alcohol derivatives, both of which present high toxicity levels. On the other hand, peroxynitrite acts as an oxidizing agent, thus strategies for its production control during food processing could help to improve food quality parameters such as taste, colour and functional properties. Therefore, the control of these degradative oxidation processes is of great interest to the food industry. In order to know in depth this problem, the present article has fo-cused on the kinetic study of the oxidation of aldehydes by peroxynitrite. The proposed mecha-nism justifies all the experimental results, passing through three competitive pathways were per-oxynitrite acts as a radical, nucleophilic or oxidant species. The possible increase of toxic prod-ucts was analyzed.