2- 9 dimer, carbon

Most of the products Hsted in Tables 1—3 are based on manufacture from tall oil fatty acids. Dimer acids based on other feedstocks (eg, oleic acid) may have different properties. A European manufacturer recently announced availabiUty of a 44-carbon dimer acid, presumably made from an emcic acid feedstock (7). 

G. Gidofalvi and D. A. Mazziotti, Application of variational reduced-density-matrix theory to the potential energy surfaces of the nitrogen and carbon dimers. J. Chem. Phys. 122, 194104 (2005). 

The rarely encountered radical addition to N=N was observed in the decomposition of diazonium salts 297. In some cases unstable derivatives of the initially formed radical 298 were obtained via nitrogen-nitrogen or nitrogen-o-carbon dimerization. ... 

Corypalline (165 R = H)249 could be oxidatively dimerized electrochemi-cally in overall yields ranging from 44 to 85% depending on experimental conditions. Two types of dimers are obtained, the amount of carbon-carbon dimer 166 decreasing when R was varied from H through methyl to ethyl, and the product distribution shifted toward the carbon-oxygen-carbon dimer 167, presumably because of steric hindrance250 [Eq. (103)]. 

When the sodium salt of 1-methylcorypalline (165 R = CH3) was oxidized in acetonitrile, a good yield of carbon-carbon dimer (69%) was obtained, in which only one of the enantiomeric pairs was obtained.251 The results were explained by proposing a surface mechanism in which the isoquinoline rings are adsorbed in a planar fashion. If the reacting molecules are adsorbed on the surface with methyl groups projecting upward, only those... 

Due to the higher reactivity of the C-C bonds at the poles of the C70 molecule that have the highest 7r-bond orders, they are exclusively involved in the above mentioned dimerizations-cycloadditions. Therefore, five [2+2] addition isomers of (C70)2 and two of the cross-dimers (C60)(C70) were formed that were finally resolved in the pure forms with the aid of recycling high-pressure liquid chromatography (HPLC). In all these all-carbon dimers (Scheme 3), the [2+2] connecting bonds can be easily cleaved under electroreductive conditions, suggesting that such kinds of dimeric materials can be used as prototypes in molecular switches based on fullerene architectures. 

Phenoxyl radicals react with each other mainly by coupling (or dimerization). Second-order decay of transient phenoxyl radicals takes place with rate constants of the order of 10 M g-i 272,296,338,352,353 leads to formation of dimeric products. Various dimers are formed by combination at the various radical sites. Since the unpaired spin is delocalized on the oxygen and on the ortho and para carbons, dimers result from combination of O with C and of C with C (equation 34). Dimers containing 0—0 bonds are less stable and generally were not detected. 

Scheme 70. Mechanism for the formation of the carbon-carbon dimer via o-dichlorobenzene approach.

Anionic Rosette Ribbon Built of Guanidinium and Hydrogen Carbonate Dimer... 

Reid CJ, Ballantine J, Rews SW, Harris F et al (1995) Charge inversion of ground-state and metastable-state C2 cations formed from electroionised C2H2 and C2N2, and a re-evaluation of the carbon dimer s ionisation energy. Chem Phys 190 113-122... 

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