2,2 -Bipyridine, reaction with magnesium

A number of other routes are available for the syntheses of diquaternary salts of 4,4 -bipyridines. One method that has been extensively studied involves reaction of a 1-alkylpyridinium salt with sodium amalgam (or sodium in liquid ammonia) to form the 1,1 -dialkyl-1,1, 4,4 -tetrahydro-bipyridine, which is readily oxidized to the corresponding l,l -dialkyl diquaternary salt. This reaction is analogous to the synthesis of 4,4 -bipyridine by the action of sodium on pyridine, followed by oxidation of the intermediate tetrahydrobipyridine. " The reduction may be achieved electrolytically or by reaction with zinc or magnesium. Various oxidizing agents have been used to assist the conversion to the di-quaternary Another synthesis of diquaternary salts of... 

The complex Mg(bpy)2-3THF can be prepared by the direct reaction of magnesium with 2,2 -bipyridine in THF and is presumably of the... 

An important method for the synthesis of bipyridines involves reaction of an alkali metal, such as sodium or magnesium, with pyridine. This process results in the formation of several isomeric bipyridines, including 2,2 -bipyridine, but the predominant isomer formed is usually 4,4 -bipyridine. This method is covered in the section devoted to the synthesis of 4,4 -bipyr-idine (Section 4-Substituted pyridines, however, readily give 4,4 -... 

The system is reversible in the absence of an added electron donor but undergoes irreversible reaction at the reduced rhenium bipyridine center in the presence of added triethylamine. The observation of reaction at the rhenium site upon excitation in the absorption band of the metalloporphyrin site is compatible with an ultrafast back electron transfer, provided that the triethylamine coordinated to the magnesium prior to absorption and that the electron transfer from the metalloporphyrin to the bipyridine was followed rapidly by irreversible electron transfer from the triethylamine to the metalloporphyrin. The experiments graphically demonstrated the benefits of the incorporation of carbonyl ligands at the electron acceptor as they allowed a tracking of the sequence of charge separation and back electron transfer via time-resolved IR data . ... 

The direct electrochemical synthesis (Scheme 2) of the addncts of organomagnesinm halides with 2,2 -bipyridine (6) and salts of organodihalogenomagnesinm(II) anions (7) was reported by Hayes and coworkers . Adducts of different stoichiometry and 7 were obtained in the electrochemical oxidation of magnesium in ACN solutions containing organic halides RX (8), a.ro-dihalides XR X (9) and 8 with ammonium salts R NX, respectively. All new products showed none of the typical reactions of Grignard reagents. 

Nickel-2,2-bipyridine complexes are also used for the preparation of unsymmetrical biaryls such as 4-methoxy-4 -trifluoromethylbiphenyl by electroreduction of two aryl halides, one of which has electron-donating and the other electron-withdrawing groups in the aromatic ring as shown in equation 110. The reaction was carried out in N-methylpyrrolidinone at constant current in an undivided cell fitted with a sacrificial magnesium anode and excess of 2,2 -bipyridine167. 

---