4,4 -Dihydroxy-2,2 -bipyridine, reaction

Complete chlorination of 4,4 -bipyridine to octachloro-4,4 -bipyridine is accomplished by vapor-phase chlorination at 555°C. Mono-, di-, tri-, and tetrachloro-4,4 -bipyridines substituted at the positions ortho to the nitrogen atoms are obtained at lower temperatures. 2,6-Dihydroxy-3-cyano-4,4 -bipyridine gives 2,5,6-trichloro-3-cyano-4,4 -bipyridine on reaction with phosphorus chlorides, ring substitution accompanying replacement... 

Dehydrogenative lactonization of diols is an efficient way to various lactones (Scheme 22). ° The lactone formation is found to be catalyzed by a recoverable stable dicationic iridium complex with 6,6 -dihydroxy-2,2 -bipyridine ligands, and employs a variety of benzylic and aliphatic diols in aqueous media. In comparison with the esterification of hydroxyl acids, hydroacyloxylation of olefmic acids and Baeyer-ViUiger reaction of cyclic ketones, the dehydrogenative lactonization of diols proceeds without any oxidant hence, it is more environmentally benign and atom economical. 

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