ИСТИНА

Modern chemical industry is experiencing a spectacular increase of the use of hetero- and homogeneous catalysts in producing different chemicals. Replacement of classical processes with other based on more effective / selective catalysts is an important target as it can significantly reduce industrial wastes [1]. Transfer hydrogenation of ketones in water by formates is a versatile and “green” method of preparing secondary alcohols with high atom-economy, however until early 2000s it was limited mostly to (partially) water-soluble substrates. Recently we have developed a convenient method for the synthesis of surface-active ruthenium complexes [(p-Cym)RuCl(Ln)] (RuLn) with a diamine ligand Ln functionalized with a quaternary ammonium group bearing long alkyls CnH2n+1 (n = 8,16) [2]. These catalysts are highly active for transfer hydrogenation of (hydrophobic) ketones in water and can be reused after catalytic cycle multiple times. Unlike RuL16, the complex with shorter alkyl “tail” RuL8 does not leach to the organic solvent phase during extraction of the product and thus can be used as a recyclable catalyst. We have shown that RuL8-based catalytic system can be used at least 10 cycles, however its strict protection from air is mandatory. Here we report the development of a recyclable micellar catalytic system based on novel surface-active complexes RhLn for reduction of ketones in water that is tolerant to air. The complexes RhL8, RhL16 were fully characterized spectroscopically, by ESI-MS and elemental analysis. The catalytic study showed that RhLn are highly active in hydrogenation of model ketone (acetophenone) in water, moreover their activity can be greatly improved by the addition of zwitter-ionic surfactant С14H29NMe2+(CH2)3SO3- (DMAPS). Interestingly, these catalysts are stable and even more active on air and thus satisfy the initial objective. We demonstrated that RhL8-based catalytic systems can perform at least 6 cycles on air without significant activity decay. Further tests with hydrophobic substrates are in progress.