Electrode Kinetic Aspects of the Kolbe Reaction

Electrophoretic deposition of graphene-related materials: A review of the fundamentals

“…Following the Kolbe-like release of CO 2 [138], the radicals that are generated recombine to recover some of the covalent bonds in the original graphene framework. Cross-linking between sheets may also contribute to the deposition process.…”

EPR Spectroscopic Characterization of the Manganese Center and a Free Radical in the Oxalate Decarboxylase Reaction

“…Purified OxDC crystallizes as a hexamer of 43-kDa subunits, each of which is a member of the "bicupin" structural family (5), and contains two mononuclear manganese centers with amino acid ligands that are functionally similar to those of manganese superoxide dismutase (MnSOD) (6); namely three histidine residues and one carboxylic acid residue. Oxalate 13 C and 18 O isotope effects on V max /K m of YvrK suggest the presence of a slow, partially rate-determining step prior to the irreversible C-C bond cleavage (4), which was proposed to be a proton-coupled electron transfer.The requirement for and substoichiometric consumption of dioxygen in the YvrK catalytic process, involvement of open shell manganese (2), and chemical precedent for oxalate decarboxylation in the Kolbe electrolysis (7,8) and the BorodinHunsdiecker reaction (9 -11) have led to various mechanistic proposals involving radical intermediates, and enzymic manganese complexes with formal oxidation states of either Mn(III) (2, 4) or Mn(IV) (3). A previously published electron paramagnetic resonance (EPR) spectrum of the enzyme in the resting state confirmed the presence of Mn(II) but did not address the question of higher valence states under turnover conditions (2).…”

“…The requirement for and substoichiometric consumption of dioxygen in the YvrK catalytic process, involvement of open shell manganese (2), and chemical precedent for oxalate decarboxylation in the Kolbe electrolysis (7,8) and the BorodinHunsdiecker reaction (9 -11) have led to various mechanistic proposals involving radical intermediates, and enzymic manganese complexes with formal oxidation states of either Mn(III) (2,4) or Mn(IV) (3). A previously published electron paramagnetic resonance (EPR) spectrum of the enzyme in the resting state confirmed the presence of Mn(II) but did not address the question of higher valence states under turnover conditions (2).…”

The long and successful journey of electrochemically active amino acids. From fundamental adsorption studies to potential surface engineering tools.

“…As pointed out in an earlier work (Dourado et al 2017), the adsorption of L-Cys is a key point for understanding certain side reactions, such as the Kolbe descarboxylation (Vijh andConway 1967, Wang et al 2015). Also, the formation of a film at the surface is an example of a self-assembling monolayer (SAMs), which was reviewed recently for different amino acids on metallic surfaces with the expectation that different effects would take place on the oxides (Costa et al 2015).…”

“…Another aspect studied was the side reaction of the descarboxilation of the adsorbed species; this was a point not considered in any other work dealing with the electrooxidation of L-Cys but treated as being of high importance for L-Tyr (Ogura et al 1999, Zinola et al 2005) and L-His (Ogura et al 1999). This kind of reaction could be related to a Kolbe Mechanism (Vijh andConway 1967, Wang et al 2015), but this kind of behavior should be more expressed in alkaline media due to the higher reactivity of the deprotonated carboxyl; but interestingly, in acid media (pH 0), this reaction was more pronounced (Dourado et al 2017). This fact was explained by the structure of the first adsorbed species, which were different from those reported for Au (Bieri and Bürgi 2005, Di Felice et al 2003, Di Felice and Selloni 2004 and Ag (Brolo et al 2002, Santos et al 2007, meaning that the carboxyl was away from the surface for Au and Ag at lower pH values and closer in alkaline media.…”