Development of water-soluble catalysts for oxidation and hydrogenation reactions

Today, there is a significant need for methods that meet the growing environmental and economic considerations and limitations. Our research program is mainly devoted to the development of organic synthetic methodologies through aqueous-phase organometallic catalysis. Hence, various water-soluble catalysts have been prepared for the synthesis of alcohols, ketones, and amines. CuCl 2 .2H 2 O/BQC (2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt) catalytic system was discovered to actively and selectively catalyze the oxidation of alcohols, alkylarenes, and alkynes with tert- butyl hydroperoxide (TBHP). Regarding hydrogen transfer reactions, the catalyst system [Ir(COD)Cl] 2 /BQC has demonstrated significant efficacy for Oppenauer-type oxidation of secondary alcohols. Conversely, the combination of [Rh(COD)Cl] 2 and P(m-C 6 H 4 SO 3 Na) 3 (TPPTS) has exhibited excellent performance in the Meerwein-Ponndorf-Verley-type reduction of aldehydes and ketones. We developed also interesting processes for the preparation of amines using molecular hydrogen. By using water soluble Pd(PhCN) 2 Cl 2 /BQC, primary and secondary amines were converted to highly alkylated amines by DRA (direct reductive amination). The in situ generated water-soluble rhodium complex derived from [Rh(COD)Cl] 2 in aqueous ammonia has also been identified as an effective catalyst for the selective hydrogenation of aromatic nitriles to primary amines, achieving very good yields. Finally, we reported that the catalyst synthesized from Pd(PhCN) 2 Cl 2 , BQC and HMS (mesoporous silica) catalyzes efficiently and selectively the hydrogenation of both aromatic and aliphatic nitriles to the corresponding secondary or tertiary amines. For the oxidation and hydrogenation reactions studied, the catalytic activity and selectivity of most of the water-soluble systems used can be maintained through recycling.