Electron spin resonance studies. Part 61. The generation and reactions of the t-butoxyl radical in aqueous solution

Analysis of 2,2’-Azobis (2-Amidinopropane) Dihydrochloride Degradation and Hydrolysis in Aqueous Solutions

“…2), alcohols (Eq. 3), and ketones were found in the solution 13,19,20. The ketone is formed by β‐scission of a tertiary alkoxyl radical (Fig.…”

“…9). This reaction is often a major degradation pathway in tertiary alkoxyl radicals and occurs at >10 6 s −1 for t ‐butoxyl radicals 20. The formation of the ketone is a propagation reaction, releasing a methyl radical that quickly adds O 2 and continues to react in solution.…”

Degradation of methyl tertiary-butyl ether (MTBE) by anodic Fenton treatment

“…The formation of double bonds in the non-radical products (e.g., HCHO, acetone, CO 2 , and CO) also contributes to the fast rates [54]. Similar to the fast ␤-scission of radical 4d to form acetone as shown in Scheme 4 (10 6 s −1 ) [59], many of the other radical ␤-and ␣-scissions in Schemes 1-5 should be rapid enough to compete with both the formation of peroxyl radical 5c (pathway c) and redox reactions with Fe 3+ /Fe 2+ (pathways d-f) in Scheme 5.…”

“…The ␣-hydrogen can rapidly shift to the oxygen [59], converting 2a to the C-centered radical Scheme 2b. 2b is potently reductive [30] and is oxidized by Fe 3+ to CH 3 OC(CH 3 ) 2 CHO (MMP).…”

“…In addition to pathways b and c, radical 5b (and radical 5h) can be oxidized by Fe 3+ to either 5d (pathway d, A = OH) or 5e (pathway e, A = alkoxyl or alkyl), depending on the nature of substitutent A (examples have been discussed in the previous sections). Finally, in the presence of an electronwithdrawing substitutent, radical 5b can be reduced to the parent compound 5a by Fe 2+ (pathway f) through an inner sphere mechanism with RO 2 -Fe 3+ as the intermediate [59,60].…”