Unexpectedly fast catalytic transfer hydrogenation of aldehydes by formate in 2-propanol–water mixtures under mild conditions

Abstract

Unsaturated aldehydes were efficiently reduced by transfer hydrogenation from sodium formate in water-2-propanol mixtures using a water-soluble Ru(II)-tertiary phosphine catalyst. The reaction yielded unsaturated alcohols with complete selectivity and without hydrogenation or isomerization of C C bonds of the substrates. Very high reaction rate was observed in the transfer hydrogenation of cinnamaldehyde already at 30 • C with turnover frequency of 160 h −1 and this increased to 3800 h −1 at 70 • C. Consequently, the method is applicable to the synthesis of unsaturated alcohols in case of heat sensitive or highly volatile aldehydes, too. Based on multinuclear NMR investigations, trans-[RuH 2 (H 2 O)(mtppms) 3 ] is suggested as the key catalytic species.

Strong Solvent Effects on Catalytic Transfer Hydrogenation of Ketones with [Ir(cod)(NHC)(PR3)] Catalysts in 2-Propanol-Water Mixtures

“…In contrast, Landaeta et al have determined the decrease of acetophenone conversion from 91% to 19% upon replacing dry 2-propanol as a solvent with a 2-propanol-water mixture containing 5% (v/v) water (x(2-propanol) = 0.82) [28]. We have also disclosed that transfer hydrogenation of aldehydes from aqueous sodium formate was largely accelerated upon addition of 2-propanol [49,50]. For these reasons, we undertook the study of transfer hydrogenation of acetophenone and benzylideneacetone in 2-propanol-water mixtures in a wide concentration range (18-100 v/v% 2-propanol) with several Ir(I)-NHC and Ir(I)-NHC-PR 3 complexes.…”

Chemoselective Transfer Hydrogenation of Cinnamaldehyde over Activated Charcoal Supported Pt/Fe3O4 Catalyst

“…The most popular hydrogen donor such as 2-propanol and formic acid/formate salt have received much more attentions [18][19][20]. For formic acid/formate salt, it is mostly utilized upon the homogeneous catalysts, such as Ir, Ru or Fe organometallic pincer complexes [19,21,22]. However, the separation and reusability of catalysts are the major concerns which are needed to be addressed.…”

Transfer Hydrogenation and Hydrogenation of Commercial‐Grade Aldehydes to Primary Alcohols Catalyzed by 2‐(Aminomethyl)pyridine and Pincer Benzo[h]quinoline Ruthenium Complexes

“…In addition to Ir complexes, the Ru Noyori system [(arene)RuCl(TsDpen)] (Tsdpen= N ‐( p ‐toluenesulfonyl)‐1,2‐diphenylethylenediamine), [CpRu(PPh 3 )(PN)] (PN=diphenyl‐2‐pyridylphosphine), [RuH 2 (PPh 3 ) 4 ], [RuCl 2 (PTA) 4 ] (PTA=1,3,5‐triaza‐7‐phosphaadamantane), [RuCl 2 ( m tppms) 2 ] 2 (mtppms=sodium 3‐diphenylphosphinobenzenesulfonate), [RuCl 2 (PO) 2 ] (PO=(2‐methoxyethyl)diphenylphosphine), [RuCl 2 (POP)(dmso)] (POP=xantphos), [RuCl 2 (PPh 3 )(NNN)] (NNN=2‐(benzoimidazol‐2‐yl)‐6‐(3,5‐dimethylpyrazol‐1‐yl)pyridine), [RuCl(PPh 3 ) 2 (MeCN) 3 ][BPh 4 ], [RuCl 2 (CO) 2 (PS)] (PS=bis(2‐diphenylphosphanylphenyl)ether monosulfide and 9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)xanthene monosulfide), and Ru cluster carbonyl derivatives catalyze the aldehyde TH using 2‐propanol or formates as hydrogen donors that work at relatively low S/C (100–1000). Complexes 2 and 3 were active in the TH of aldehydes with NaO i Pr and K 2 CO 3 as the base.…”