2,2 -Bipyridine-4,4 -dicarboxylic acid, reaction

Reaction of -picoline over degassed Raney nickel was found to give 5,5 -dimethyl-2,2 -bipyridine (5), the structure of which was established by its synthesis from 2-bromo-5-methylpyridine. Oxidation of this dimethyl-2,2 -bipyridine, and similar oxidation of the diethyl-2,2 -bipyridine derived from 3-ethylpyridinc, gave the corresponding dicarboxylic acid and the same acid was produced by the action of degassed Raney nickel on sodium nicotinate (in water) or on ethyl nicotinate. These transformations established the 5,5 -substitution pattern for three 2,2 -bipyridines derived from 3-substituted pyridines but such evidence is not available for the biaryls... 

Methyl-3,3 -bipyridine has been oxidized by permanganate to 3,3 -bi-pyridine-4-carboxylic acid. " 3,3 -Bipyridine carboxylic acids are easily decarboxylated and have been esterified and converted to amides, hydrazides, and acylazides. The Hofmann degradation, of the diamide of 3,3 -bipyridine-2,2 -dicarboxylic acid affords the expected 2,2 -diamino-3,3 -bipyridine, but some of the tricyclic system 108 is formed as well. A 2,2 -bis(acylazide) is converted to a similar tricyclic system with ethanol via the intermediate isocyanate, and several related reactions have been described. The simultaneous dehydration... 

The electrophilic reactions of co-ordinated 1,10-phenanthrolines are not always as simple as might be expected. Thus, the nitration of cobalt(m) 1,10-phenanthroline complexes yields 5-nitro-1,10-phenanthroline derivatives at low temperature, but prolonged reaction in hot solution leads to further reaction and oxidation of the ligand to give excellent yields of 1,10-phenanthroline-5,6-quinone complexes (Fig. 8-40). Even after the formation of the quinone, the complexes may exhibit further reaction. For example, reaction of the l,10-phenanthroline-5,6-quinone complexes with base results in the formation of a complex of 2,2 -bipyridine-3,3 -dicarboxylic acid (Fig. 8-41)... 

The solution and nujol-matrix photochemical reactions of CpM(CO)2H (M = Ru or Os), (ri -C5H4CH3)2Ru2(CO)4 and Cp20s2(CO)4 were followed by IR spectroscopy (vCO). Photochemical reactions of trans-(X)-Ru(dcbpy)(CO)2X2, where X = Br or I, dcbpy = 4,4 -dicarboxylic acid-2,2 -bipyridine, were monitored similarly. IR data were reported for two polymorphs of the cluster Ru4Pt2(CO)i8, i.e. the known monoclinic and a new orthorhombic form. ... 

Such acid-base reactions take place at the carboxylic groups of suitable ligands such as L-L = 2,2 -bipyridine-4,4 -dicarboxylic acid. e.g. [Ru(bipy)2(L-L)]2+ [131]. In acidic D2O solutions of the Ru(II)-complex [Ru (NH3)5(pyridine)]2+ a light-induced H/D exchange occurs at the pyridine ligand [10,132]. This reaction is also attributed to the enhanced basicity of the coordinated pyridine in the MLCT excited state. 

Polyamides and polyesters containing ruthenimn bipyridine complexes in their structures have been synthesized by Chan and coworkers." " Scheme 14 depicts the synthesis of polymer 64 by reaction of the metal-containing dicarboxylic acid complex 61 and the organic dicarboxylic acid (62) with an aromatic or aliphatic diamine (63). These polymers were thermally stable to temperatures between 320 and 500°C. Many of the polymers exhibited liquid crystalline characteristics. The photoconductivity of this class of polymer increased with increasing metal content." Chan also reported that polybenzo-bw-oxazoles and polybenzo-Z>w-thiazoles that contain ruthenium complexes coordinated to 2,2 bipyridyl units in the backbone... 

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