2,2 -bipyridine from

The formation of trace amounts of 2,2 -bipyridine following reaction between pyridine and ammonia in the presence of a variety of catalysts led Wibaut and Willink to develop a method for the preparation of 2,2 -bipyridine from pyridine under the influence of a nickel-alumina catalyst. Using a pyridine-to-catalyst ratio of 10 1, temperatures between 320° and 325°C, and pressures between 42 and 44 atm, 2,2 -bipyridine was formed in yields of 0.30-0.67 gm per gram of catalyst. This method w as later applied to -picoline, to quino-line, - and to some of its derivatives, ... 

The Preparation of Substituted 2,2 -Bipyridines from Substituted Pyridines and Degassed Raney Nickel -i ... 

In the absence of an added solvent, 3-alkyIpyridines, 4-alkyl-pyridines, and 3,4-dialkylpyridines all gave yields of substituted 2,2 -bipyridines that were up to three times greater than that of 2,2 -bipyridine from pyridine under similar conditions. With 3-ethyl-4-methylpyridine a marked improvement in yield was ob.served when the reaction was carried out at about 150°C in a vacuum, rather than at the atmospheric boiling point (195°C) of this base. This effect has also been observed with some other bases but the amount of 3,3, 5,5 -tetramethy 1-2,2 -bipyridine from 3,5-lutidine could not be increased in this way, and this pyridine was as unreactive as the 2-substituted pyridines. This finding is undoubtedly related to the reluctance of 3-substituted pyridines to form 3,3 -disubstituted 2,2 -bipyridines. 

The three catalysts which have been used for the preparation of 2,2 -bipyridines from pyridines have also been employed for the preparation of 2,2 -biquinolines from quinolines. Tlie results have... 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

The outstanding feature of the preparation of 2,2 -bipyridine from pyridine under the influence of metal catalysts is the absence of isomeric bipyridines among the products. In this respect reactions using metal catalysts in a heterogeneous system differ from methods which have been used to prepare bipyridines in homogeneous sys-tems. ... 

Several lithium reagents have been found to convert pyridine to 2,2 -bipyr-idines in satisfactory yield. Following from the formation of 2,2 -bipyridines from 2-lithiopyridines, it has been found that 2-benzyl-2-lithio-1,3-dithiane forms 2,2 -bipyridine in 30-75% yield when refluxed with pyridine in tetrahydrofuran, " and related compounds behave similarly. Lithium diisopropylamide with pyridine in ether affords up to 50% 2,2 -... 

For [Cr(CO)4(phen)] and [W(CO)4(phen)], the crystal structures are known (85CJSC66, 85CJSC69, 90MK129). The ability of 1,10-phenanthroline to substitute 2,2 -bipyridine from [Mo(CO)4(bpy)] is ascribed to the more expressed ji-acceptor function and rigidity of the 1,10-phenanthroline ligand (88IC81). 

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