Reactions in “sacrificial” solvents

Abstract

The involvement of organic solvents in redox reactions and their influence on the efficiency and ''greenness'' of the desired chemical transformation are critically reviewed. Some representative examples are presented on the co-oxidation and co-reduction of widely used solvents (alcohols, ethers, nitriles, amides, sulfoxides, hydrocarbons, dense CO 2 ), and on the impact of these frequently hidden reactions. The transformation of the solvent may be limited to its unintended consumption leading to an increase in the E-factor, but it may also play a critical role in the reaction investigated and lead to false interpretation of reaction mechanisms. In fact, the approach of using a ''sacrificial'' solvent as a part of the oxidizing system may be an attractive-but surely not a green-alternative in synthetic chemistry. Finally, the crucial but often unrecognized role of the solvent in stabilizing or destabilizing catalytic metal nanoparticles is discussed. Surface redox reactions involving the solvent can be decisive for switching between heterogeneous and homogeneous catalytic pathways.

Electron tunneling of hierarchically structured silver nanosatellite particles for highly conductive healable nanocomposites

“…An additional strong O-C=O peak (1569 cm −1 ), corresponding to conjugated γbutyrolactone, was observed for the AgNS-AgFLs. The 2-hydroxy tetrahydrofuran, formed in the reaction medium, generated conjugated γ-butyrolactone as a byproduct upon further oxidation 35,36 . Additional peaks related with SR (Si(CH 3 ) 2 stretching, Si-O-Si stretching, Si-CH 3 stretching, and CH bending) were observed for the AgNS-AgFL-SR nanocomposite 37 .…”

The Influence of Alkali Metal Ions on the Stability and Reactivity of Chromium(III) Superoxide Moieties Spanned by Siloxide Ligands

“…By using propionitrile as a solvent, a drastic increase in reactivity was observed (making the determination of rate constants for 4 +O 2 impossible), with no change in the overall trend (see Section 1.3.1.2 in the Supporting Information). Notably, an active participation of the solvents in the reaction mechanism, as an alternative conceivable explanation,—could be ruled out (Section 2, Supporting Information). When the experiments were repeated with 2,6‐dimethylphenol as the substrate (BDE 84.50 kcal mol −1 ), which has a far stronger O−H bond, the reaction slowed down to such an extent that an extra set of absorption bands could be observed by UV/Vis spectroscopy (Li + 561, 594; Na + 507, 583; K + 509, 574 nm).…”

A Mechanistic Study on the Nucleation and Growth of Au on Pd Seeds with a Cubic or Octahedral Shape

“…The report of Yuan et al., [87] however, remains a significant breakthrough, for although H 2 O 2 had previously been identified as a suitable oxidative species for methane oxidation, its use was typically reported in chemically reactive organic solvents 88. 90 Care must be taken whilst examining these previous results, therefore, as it has previously been reported that this can lead to both the formation of more reactive oxygen donors (such as peroxyacetimidic acid or peroxycarboximidic acid) or lead directly to C 1 ‐oxygenated species via co‐oxidation or degradation of the organic solvent 91. This is hugely undesirable on a process level, as it results in the production of non‐methane‐derived oxygenated species and the degradation of the desired solvent.…”