And the Nef reaction

Thermochemically is the operative word here. After all, NO can formally delocalize and thus stabilize both negative and positive charges as illustrated by the acidity of oximes cf. the well-established existence of (R2CNO) and the Nef reaction, cf. the putative existence of (R2CNO)+. 

Studies into oxidative dimerization have shown that only the persulfate anion is of synthetic value in these reactions. Reaction pH is also crucial with reactions proceeding fastest when a pH of 7.2-9.4 is maintained. " The reaction medium becomes more acidic as the oxidation progresses and needs either buffering or the slow addition of alkali throughout the reaction. If the reaction medium is allowed to become acidic then the starting nitroalkane is regenerated and the Nef reaction predominates. 

Due to the basicity of the (concave) pyridine, in a buffer most protons are located on the pyridine nitrogen. The concentration of free EtOH is small. Therefore in the standard pyridine buffer the C-protonation is faster than O-protonation. However, in a buffer containing a concave pyridine 3, the protonated nitrogen atoms of the concave pyridines 3 are shielded. This retards the C-protonation and a small concentration of protonated ethanol (EtOHj) is sufficient for O-protonation and the Nef-reaction. Thus, the Nef-reaction is possible in a buffered medium, under softer conditions than with mineral acids. The reaction was therefore called the Soft Nef-Reaction. 

Grierson, D. S., Husson, H.-P. Polonovski- and Pummerer-type reactions and the Nef reaction, in Comp. Org. Synth, (eds. Trost, B. 

The Weerman degradation was employed in one of the first preparations of dialdoses, namely of n-f/ireo-tetrodialdose, using the diamide of D-glucaric acid as starting material. An inosose has been degraded to a pentodialdose by way of its disulfone and the Nef reaction, transformation of a 6-deoxy-... 

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