Selective Hydrogenation Of Quinolines And Isoquinolines Catalyzed By Thermoregulated Phase-separable Platinum And Iridium Nanoparticles

Thermoregulated phase-separable Pt and Ir nanoparticles were prepared using IL_PEG1000as a stabilizer which possesses the critical solution temperature?CST?property and H₂ as the reductant.The nanoparticles can realized the process of thermoregulated phase-separable catalysis?TPSC?in the mixture of toluene and n-heptane,and the principle of TPSC is that at room temperature?T<CST?,the system is biphasic with a clear interface.The upper layer is the organic phase containing toluene and n-heptane,and the lower is the ionic liquid phase containing thermoregulated phase-separable nanoparticles.When heated to the reaction temperature?T>CST?,the catalyst mixes with organic phase forming a homogeneous phase.When the temperature cooing down the catalyst can precipitate from the organic phase,and the system turns into biphasic again.The catalyst can be separated from the organic phase by simple phase separation,and the catalyst can be reused directly.The thermoregulated phase-separable nanoparticles showed high catalytic activity and high selectivity,details are as follows:Thermoregulated phase-separable Pt nanoparticles were employed as catalyst for selective hydrogenation of quinoline.Under the optimized reaction conditions,IL_PEG1000/Pt=200?molar ratio?,T=130°C,P_H2=4 MPa,t=3 h,quinoline/Pt=1200?molar ratio?,both the conversion of quinoline and the selectivity for target product 1,2,3,4-tetrahydroquinoline?1-THQ?could reach more than 99%,the catalyst could be used 12 times without evident loss in catalytic activity.The turnover number?TON?was up to 14136 which was close the highest value ever reported for Pt nanoparticles catalyzed selective hydrogenation of quinoline.Thermoregulated phase-separable Ir nanoparticles were employed as catalyst for selective hydrogenation of isoquinoline.Under the optimized reaction conditions,I₂/Ir=30?molar ratio?,IL_PEG1000/Ir=30?molar ratio?,T=130°C,P_H2=5 MPa,t=5 h,isoquinoline/Ir=200?molar ratio?,both the conversion of isoquinoline and the selectivity for target product1,2,3,4-tetrahydroiso?1-THIQ?quinoline could reach more than 99%.The catalyst could be recycled with no evident in activity 10 times.The turnover number?TON?was up to 1910.The results showed that thermoregulated phase-separable Ir nanoparticles have good catalytic activity in the selective hydrogenation of isoquinoline,filling the blank of selective hydrogenation of isoquinoline by Ir nanoparticles.