Name: (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diolOn October 28, 2002 ,《Electronic Differences between Coordinating Functionalities of Chiral Phosphine-Phosphites and Effects in Catalytic Enantioselective Hydrogenation》 was published in Organometallics. The article was written by Suarez, Andres; Mendez-Rojas, Miguel A.; Pizzano, Antonio. The article contains the following contents:
A convenient synthesis of new chiral phosphine-phosphites (P-OP) was described. The versatility of the synthetic protocol developed gave ligands with different phosphine fragments and the choice of the stereogenic element location. Analyses of the values of 1JPSe of the corresponding diselenides are in accord with the expected lower σ-donor ability of the phosphite fragment, with respect to the phosphine group, and with an increase of phosphine basicity after substitution of Ph substituents by Me groups. Inspection of υ(CO) values on complexes RhCl(CO)(P-OP) demonstrated a variable π-acceptor ability of the phosphite group, compensating for the change of basicity of the phosphine functionality, as well as having a rather reduced electron d. at the metal center compared with diphosphine analogs. The distinct nature of the P functionalities also was evidenced in Rh-catalyzed enantioselective hydrogenation of Me Z-α-acetamidocinnamate (MAC). Thus, the coordination mode of the substrate is governed by the chiral ligand, directing the olefinic bond to a cis position with respect to the phosphite group, as demonstrated by NMR studies performed with [Rh(P-OP)(MAC)]+ complexes. In consequence, the phosphite group has a greater impact on the enantioselectivity of the product. However, the optical purity of the process also depends on the nature of the phosphine group, and hence, an appropriate election of both P functionalities is required for the attainment of excellent enantioselectivities (99% ee). After reading the article, we found that the author used (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol(cas: 329735-68-4Name: (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol)
(R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol(cas: 329735-68-4) belongs to phenols. Phenols are more acidic than typical alcohols.Name: (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids (their pKa is usually between 10 and 12).
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