In 1968,Tetrahedron included an article by Pala, Gianfranco; Crescenzi, Elda; Bietti, G.. SDS of cas: 16985-07-2. The article was titled ãNew synthesis of 4,4′-dihydroxydiphenyl(2-pyridyl)-methaneã? The information in the text is summarized as follows:
Condensing phenol with 2-pyridine carboxaldehyde was shown to give 4,4′-dihydroxydiphenyl(2-pyridyl)methane (I) together with 24-29% of its isomer 2,4′-dihydroxydiphenyl(2-pyridyl)methane (II). Recrystallization of the mixture, required to obtain I free from II, caused the yield of I to fall to scarcely 25%, based on 2-pyridine carboxaldehyde. To prevent or reduce formation of ortho condensation products, 2-pyridine carboxaldehyde was made to react with phenols halo-substituted in both or in a single ortho position. Reductive dehalogenation of the compounds thus obtained gave I in 65-70% yield. The results came from multiple reactions, including the reaction of 2,2′-(Pyridin-2-ylmethylene)diphenol(cas: 16985-07-2SDS of cas: 16985-07-2)
2,2′-(Pyridin-2-ylmethylene)diphenol(cas: 16985-07-2) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. SDS of cas: 16985-07-2The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds.