Rate constants of carbonate radical anion reactions with molecules of environmental interest in aqueous solution: A review

The rate constants of carbonate radical anion (CO3 center dot-) reaction with organic molecules, mainly of environmental interest, were collected from the literature and structure effects were discussed together with methods of rate constant determination and reaction mechanisms. These rate constants are essential for modelling chemical processes taking place with participation of reactive radicals in the environment determining the persistence of certain toxic compounds. The rate constants span over a very wide range from 10(2) to 10(9) mol(-1) dm(3) s(-1), but, even the highest values are smaller by a factor of 2-5 as the diffusion controlled limit. This survey shows that only those molecules have high rate constants in the 10(7)-10(9) mol(-1) dm(3) s(-1) range which have special electron rich part(s). These molecules are removed selectively in CO3 center dot- reactions. Such electron rich moiety is the NH2 group attached to an aromatic ring. High vales weremeasured e.g., for most of anilines or the sulfonamide antibiotics. -CO group attached to theN-atom(in acetanilides and in phenylurea herbicides), or strong electron withdrawing substituents on benzene ring strongly decrease the rate constant. High values were also measured for aromatic molecules with dissociated -OH group (O-, phenoxides). The thioether group (e.g., in amino acids, or in fenthion or phorate insecticides) also activates the molecules in CO3 center dot- reactions. (c) 2020 Elsevier B.V. All rights reserved.