2,3 -Bipyridyls

One 1-ml aliquot is added to 1.0 ml of freshly-distilled 1,2-dibromo-ethane (bp 132°C) in an oven-dried flask which contains a static atmosphere of nitrogen or argon. After the resulting solution has been allowed to stand at 25°C for 5 min, it Is diluted with 10 rat of water and titrated for base content (residual base) to a phenolphthalein endpoint with standard 0.100 M hydrochloric acid. The second 1-mL aliquot is added cautiously to 10 ml of water and then titrated for base content (total base) to a phenol phthalein endpoint with standard aqueous 0.100 M hydrochloric acid. The methyllithium concentration is the difference between the total base and residual base concentrations.2 Alternatively, the methynithiura concentration may be determined by titration with a standard solution of sec-butyl alcohol employing 2,2 -bipyridyl as an indicator. 

Bipyridyl [366-18-7] M 156.2, m 70.5 , b 273 , pK -0.52, pK 4.44. Crystd from hexane, or EtOH, or (after charcoal treatment of a CHCI3 soln) from pet ether. Also ppted from a cone soln in EtOH by addition of H2O. Dried in a vacuum over P2O5. Further purification by chromatography on AI2O3 or by sublimation. [Airoldi et al. J Chem Soc, Dalton Trans 1913 1986.]... 

Other, closely related, nicotinic acid derivatives and the unsubstituted system itself have also been studied and undergo similar reactions. Moreover, the approach may be extended to 2,2 -bipyridyls. Newkome and his collaborators have used the 2,2 -bipyridyl unit 19) as an electrophile in which ortho-hr ommes served as leaving groups. They have also used halomethyl systems and formed the macrocycles from these systems . A compound derived from the latter starting material 20) is reported to form a cobalt complex, in which both nitrogens and only one of the oxygen atoms participate in the binding . The two precursor units are shown below as 79 and 20, respectively. 

The neutral radical 11.12 is an interesting heterocyclic analogue of 2,2 -bipyridyl. This paramagnetic (spin-bearing) ligand forms an N, -chelated complex with bis(hexafluoroacetylacetonato)cobalt(ir). ... 

Organometallic compounds apart, oxidation states below - -2 are best represented by complexes with tris-bidentate nitrogen-donor ligands such as 2,2 -bipyridyl. Reduction by LiAlH4 in thf yields tris(bipyridyl) complexes in which the formal oxidation state of vanadium is -1-2 to —1. Magnetic moments are compatible with low-spin configurations of the metal but. 

Other, 174, the product of a known ring opening reaction (97T8257). Ring opening of compounds of type 173 gives 2,2 -bipyridyls (98T15287) (see Section IV.F). 

Basicity measurements of 4-amino-2,2 -bipyridyl and some of its N-substituted derivatives have shown that, when an electron-withdrawing substituent is present, the protonation occurs at the distant ring and derivatives with electron-donating substituents are protonated at N(l) of the substituted ring [78JCS(P2)1215]. 

The reaction was carried out analogously to the general procedure for the addition of metalated ally 1 sulfoxides given in Section 1.5.2.2.3.2. BuL.i is used, in this case, for deprotonation instead of LDA. BuLi is added to a solution of 1 - 3 mmol of the phosphine oxide or phosphonate in THF until the first permanent appearance of the red color of the anion. Thereupon, 1.1 equivalents of the BuLi is added. For the phosphonates, whose anions are less intensely colored, 1.1 equivalents of BuLi are added to the solutions after the first permanent appearance of the red color of an added indicator, 2.2 -bipyridyl. 

Complexes of the more rigid 2,2 -bipyridyl and 1,10-phenanthroline are made ... 

Analytical chemistry of metal complexes with nitrogen-containing ligands of the 2,2 -bipyridyl type. A. T. Pilipenko and E. R. Falendysh, Russ. Chem. Rev. (Engl. Transl.), 1972, 41, 991-1008 (249). 

Bipyridyl,4-methyl-4 -vinyl-electrochemical polymerization, 6,25 electropolymerization, 6,16 Bipyridyls bis(ZV-oxide) metal complexes, 2, 496 metai complexes, 2, 89, 90,93 steric effects, 2, 90 2,2 -Biquinolyl... 

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