Reaction mechanisms reduction

FIGURE 13.6 Fluorenone reduction reaction mechanism. (Adapted from Nakagawa, K. and Minami, K., Tetrahedron Lett., 5, 343-346, 1972.)... 

Dr. Fred Guengerich at Vanderbilt University has published mechanistic schemata for cytochrome P450 involvement in an extensive array of both common and uncommon oxidative reactions and reductive reactions. Some of those are exhibited later in this chapter in a brief consideration of reductive reactions. Mechanisms for carbon hydroxylation, heteroatom oxygenation, N-dealkylation, O-dealkylation, alcohol oxidation, arene epoxidation, phenol formation, oxidation of olefins and acetylenes, reduction of nitro compounds, reductive dehalogenation, and azo reduction, to name a few, are provided. 

Step 6 is the final step in the cellulose-to-lactic acid cascade, involving the isomerization of the 2-keto-hemi-acetal (here pyruvic aldehyde hydrate) into a 2-hydroxy-carboxyhc acid. This reaction is known to proceed in basic media following a Cannizzaro reaction with 1,2-hydride shift [111], Under mild conditions, Lewis acids are able to catalyze this vital step, which can also be seen as an Meerwein-Ponndorf-Verley reduction reaction mechanism. The 1,2-hydride shift has been demonstrated with deuterium labeled solvents [110, 112], Attack of the solvent molecule (water or alcohol) on pymvic aldehyde (step 5) and the hydride shift (step 6) might occur in a concerted mechanism, but the presence of the hemiacetal in ethanol has been demonstrated for pyruvic aldehyde with chromatography by Li et al. [113] andfor4-methoxyethylglyoxal with in situ CNMRby Dusselier et al. (see Sect. 7) [114]. 

Yu L, Pan X, Cao X, Hu P, Bao X. Oxygen reduction reaction mechanism on nitrogen-doped graphene a density functional theory study. J Catal 2011 282 183-90. 

Tripkovic V, Skulason E, Siahrostami S, Norskov JK, Rossmeisl J. The oxygen reduction reaction mechanism on Pt(lll) from density functional theory calculations. Electrochim Acta 2010 55 7975-81. 

Olson TS, Pylypenko S, Fulghum JE, Atanassov P (2010) Bifunctional oxygen reduction reaction mechanism on non-platinum catalysts derived from pyrolyzed porphyrins. J Electrochem Soc 157 B54—B63... 

Chen R, Li H, Chu D, Wang G (2009) Unraveling oxygen reduction reaction mechanisms on carbon-supported Fe-phthalocyanine and Co-phthalocyanine catalysts in alkaline solutions. J Phys Chem C 113(48) 20689-20697... 

First-Principles Insights in ORR Catalysis for PEMFC 21.3.1 Oxygen Reduction Reaction Mechanism... 

Figure 2.16. The oxygen reduction reaction mechanism on Pt [42]. (Reprinted from Surface Seience Reports, 45(4-6), Markovi N. M. and Ross P. N., Surface science studies of model fuel cell electrocatalysts, 117-229, 2002, with permission from Elsevier.)...

Key words polymer electrolyte membrane fuel cell, direct methanol fuel cell, oxygen reduction, reaction mechanism, core-shell, platinum-fiee. 

Pillihuaman, A. Takano, C. Nogueira, A. Mouiao, M. Iguchi, Y Chromites reduction reaction mechanism in Carbon-Chromites composite agglomerates at 1773 K. ISIJ,... 

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