Comproportionation,

An important series of reactions, which illustrates the diversity of behaviour to be expected, is the comproportionation of halates and halides. Bromides are oxidized quantitatively to bromine and iodides to iodine, this latter reaction being much used in volumetric analysis ... 

A microwave-assisted three-component reaction has been used to prepare a series of 1,4-disubstituted-1,2,3-triazoles with complete control of regiose-lectivity by click chemistry , a fast and efficient approach to novel functionalized compounds using near perfect reactions [76]. In this user-friendly procedure for the copper(l) catalyzed 1,3-dipolar cycloaddition of azides and alkynes, irradiation of an alkyl halide, sodium azide, an alkyne and the Cu(l) catalyst, produced by the comproportionation of Cu(0) and Cu(ll), at 125 °C for 10-15 min, or at 75 °C for certain substrates, generated the organic azide in situ and gave the 1,4-disubstituted regioisomer 43 in 81-93% yield, with no contamination by the 1,5-regioisomer (Scheme 18). 

Comproportionation to form [CljGaGaC ] to the extent of ca. 5% occurs when GaClj, which has structure Ga [GaCl4], is melted with Ga at 180°C ... 

I. by Comproportionation with the Group-IIIB Element or Its Univalent State... 

Kurzydlowski, D. and Grochala, W. (2000) Elusive AuF in the Solid State As Accessed via High Pressure Comproportionation. Chemical Communications, (9), 1073-1075. 

Giulivi, C. and Davies, K. (1990). A novel antioxidant role for haemoglobin. The comproportionation of ferryl haemoglobin with oxyhaemoglobin. J. Biol. Chem. 265, 19453-19460. 

In general, thermodynamic stability of a mixed-valence dinuclear complex, which is denoted as a combination of reduced (Red) and oxidized (Ox) sites, Red-Ox, is exhibited as a difference in redox potentials AE° = E°(Ox-Ox/Red-Ox) - °(Red-Ox/Red -Red). This difference is related to the comproportionation constant, Kc, defined in Eq. (1) ... 

The free energy of comproportionation, AGc, involves several factors, as given in Eq. (2) by Sutton et al. ... 

The simplest variant of the selective catalytic reduction of NO with NH3 is the standard-SCR reaction, in which NH3 and NO comproportionate in a 1 1 stoichiometry to nitrogen. This reaction is efficiently catalyzed with high activity and selectivity between 300 and 400°C by V205/W03-Ti02 catalysts, which are wide-spread in stationary SCR systems [1],... 

Comproportionation equilibrium constants for Equation 9.3 between dications and neutral molecules of carotenoids were determined from the SEEPR measurements. It was confirmed that the oxidation of the carotenoids produced n-radical cations (Equations 9.1 and 9.3), dications (Equation 9.2), cations (Equation 9.4), and neutral ir-radicals (Equations 9.5 and 9.6) upon reduction of the cations. It was found that carotenoids with strong electron acceptor substituents like canthaxanthin exhibit large values of Kcom, on the order of 103, while carotenoids with electron donor substituents like (J-carotene exhibit Kcom, on the order of 1. Thus, upon oxidation 96% radical cations are formed for canthaxanthin, while 99.7% dications are formed for P-carotene. This is the reason that strong EPR signals in solution are observed during the electrochemical oxidation of canthaxanthin. 

Israeli, A., Patt, M., Oron, M., Samuni, A., Kohen, R., and Goldstein, S. 2005. Kinetics and mechanism of the comproportionation reaction between oxoammonium cation and hydroxy-lamine derived from cyclic nitrones. Free Radical Biology and Medicine 38 317-324. 

In solutions with relatively high ammonia concentrations, NH3 reacts with NP to give Fe(CN)5(H20)3 plus N2, effecting comproportionation of NH3 and NO+ to N2 (60,52c). Likewise, primary amines (RNH2) are diazotized by aqueous NP to give the alcohols (ROH) plus N2, with the maximum rate occurring about pH 10.5 (55). The rates of these reactions are first-order in [NP] and [RNH2] and increase with the basicity of the amines. 

It should be recalled that in the case of the EE mechanism, in solution one can have the comproportionation reaction ... 

In fact, when there is no interaction a statistical treatment shows that the comproportionation constant, Kcom, takes a value of 4 and, therefore, AE° = 35.6 mV. In this case the cyclic voltammogram is of... 

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