Proton-Coupled Electron Transfer in the Reaction of 3,4-Dihydroxyphenylpyruvic Acid with Reactive Species in Various Media

Table 5

Parameters characterizing the O–H bond cleavage in selected media. in Å is the distance from the oxygen of the phenoxyl moiety to the moved hydrogen atom . in is the corresponding frequency associated with the movement of this hydrogen atom, while and in ⋅⋅ are the associated rate constants using, respectively, TST/ST and TST/ZCT methods. in is the activation free energy, and = 3, 4. NA stands for not applicable.

Media
Related to the attacked site
Vacuum	0.969	3769	31.2	6.8 10	5.0 10
Cyclohexane	0.975	3645	47.0	1.6 10	3.5 10
Benzene	0.976	3625	53.8	5.1 10	7.1 10
Methanol	0.990	3331	71.8	3.6 10	2.5 10
Water	0.991	3326	78.3	4.8 10	1.6 10
Related to the attacked site
Vacuum	0.964	3710	68.1	1.9 10	6.2 10
Cyclohexane	0.975	3661	—	—	—
Benzene	0.976	3652	78.6	2.9 10	NA
Methanol	0.983	3493	93.3	1.7 10	6.1 10
Water	0.985	3457	90.9	—	—