The fastest improvement of the wealth and quality of life was witnessed in last decades by the humanity globally. Economic and social development, however, influenced the state and processes of the natural environment at the same time significantly. Food supply is one of the major interfaces between the society and the natural resources, as we highlight in our literature review; approximately one-third of the resource use and pollution is originated in nutritional needs. Also, health effects of western diet are remarkable. Consequently, debate on 'healthy diet' and 'environmentally friendly' food supply chain became complementary and reinforcing topics recently, at least in the scientific communication.

In this paper, a double exponential approximating approach is described for a quite common kinetic model (mixed second‐order formation of an intermediate followed by its first‐order decay) under non‐pseudo–first‐order conditions (i.e., when the initial ratio of the two reactants is between 1 and 10). For the evaluation, first the exact kinetic curves predicted by the two‐step model were calculated and then fitted to a double exponential function. The goodness of the fits and the estimated parameters of the double exponential function for both I and P concentrations were determined as a function of the rate constants and initial concentrations in the two‐step model. It was found that the fit of the double exponential function is acceptable or very good under these conditions despite the fact that none of the reagents is in a large excess. Since UV–vis absorption spectroscopy is probably the most common technique to follow kinetic traces, we also made efforts to deal with the typical properties of monitoring the process through UV–vis. It was found that the experimental curves can be fitted quite well with a double exponential function if the reagents have minor absorption compared to the intermediate and/or product. The connection between the observed rate constants and the rate constants of the above‐mentioned mechanism is also studied.

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Table of contents entryThe kinetics of the reactions between 1,4-benzoquinones and hydrogen peroxide were studied.A systematic study of substituent effects revealed a Hammett-like correlation, where the rate of reaction is mainly determined by electronic effects. 3 AbstractThe kinetics and mechanisms of the redox reactions between hydrogen peroxide and 1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2,6-dimethyl-1,4-benzoquinone, 2-chloro-1,4-benzoquinone and 2,6-dichloro-1,4-benzoquinone were studied in aqueous media using spectrophotometric monitoring. The formation and decay of a hydroxylated 1,4-benzoquinone was detected. The formation of the intermediate was first order with respect to the parent 1,4-bezoquinone and hydrogen peroxide, whereas inverse first order dependence was revealed with respect to hydrogen ion. The decomposition reaction had two parallel pathways: one was first order with respect to the intermediate, while the other showed second-order dependence.The values of the rate constant measured for the formation step were successfully correlated with both the redox potentials of the substituted quinone/hydroquinone systems and the pK a values of the hydroxylated quinone derivatives. Therefore, electronic effects govern the reactivity of the quinones in this process. NMR and GC-MS measurements were carried out to identify the products in the system. Quantum mechanical calculations were also carried out in these systems.4

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