Catalytic transfer hydrogenation of hydrophobic substrates by water-insoluble hydrogen donors in aqueous microemulsions

Asymmetric Transfer Hydrogenation in Thermomorphic Microemulsions Based on Ionic Liquids

“…Further studies on the effect of temperature showed that a lower yield can be compensated with increasing temperature (entries 10−14). 28,29 The excellent enantioselectivity was maintained even at a temperature of 70 °C, which is in accordance with our previous observations. 20 The results for entries 15−18 suggest that the addition of an appropriate amount of water (i.e., decreasing γ while keeping the ionic liquid amount constant at 0.3 g) is beneficial to increase the yield of the reaction.…”

“…26,27 So far, only few examples on transfer hydrogenation in microemulsions were reported. 22,28 Batarseh et al investigated the transfer hydrogenation of various unsaturated substrates by cyclohexene and similar water-insoluble hydrogen donors in aqueous microemulsion at 100−140 °C, relying mostly on fatty alcohol polyethylene glycol ethers as nonionic surfactants. 28 The influence of surfactant was also a key aspect in a study by Schwarze et al in 2015, addressing the transfer hydrogenation of 4-acetylbiphenyl with 2-propanol as the hydrogen donor, Rh/TPPTS as catalyst, and K 2 CO 3 as base.…”

“…22,28 Batarseh et al investigated the transfer hydrogenation of various unsaturated substrates by cyclohexene and similar water-insoluble hydrogen donors in aqueous microemulsion at 100−140 °C, relying mostly on fatty alcohol polyethylene glycol ethers as nonionic surfactants. 28 The influence of surfactant was also a key aspect in a study by Schwarze et al in 2015, addressing the transfer hydrogenation of 4-acetylbiphenyl with 2-propanol as the hydrogen donor, Rh/TPPTS as catalyst, and K 2 CO 3 as base. 22 A strong influence of the surfactant on the catalytic activity was observed, as TX-100 showed about 10% higher conversions compared to fatty alcohol polyethylene glycol ethers in a threephase n-heptane/water/surfactant/2-propanol microemulsion system, although higher concentrations of TX-100 led to a decrease in activity.…”

Ni-NHC Nanoparticles in Micelles as an Effective and Reusable Catalyst for Hydrogenations and Reductive-Aminations in Water

“…Therefore, our catalytic system was rather active and chemoselective but slower than previous studied Pd catalysts stabilized by surfactants. Indeed, by operating under 1 to 14 bar H 2 pressures ,− or through hydrogen transfer, ,, they reduced quantitatively alkenes within 0.5 to 12 h, at room temperature or higher in some cases.…”

“…Catalytic applications of metallomicelles appear promising for the sustainable synthesis of bulk and fine chemicals and catalyst recycling. For example, several systems based on Pd/C, Pd organometallics, or nanoparticles have been reported as effective catalysts for cross-coupling reactions, ,− transfer hydrogenations ,− and hydrogenations. − Indeed, such metallomicelles have hydrophobic/lipophilic inner cores that allow the solubilization of organic reagents, as well as the catalysis of their reactions, and hydrophilic exterior domains. The catalytic processes within their inner core can proceed in water, and a full separation of the organic products from the aqueous reaction medium is possible through extraction, decantation, or filtration.…”