Thermoregulated Phase-Separable Palladium Nanoparticles Catalyzed Carbonylative Sonogashira Coupling And Aminocarbonylation Of Aryl Iodides

Ionic liquids ILPEG1000 ([CH₃?OCH₂CH₂?₂₂N+Et₃][CH₃SO₃^-]), which possesses the critical solution temperature ?CST? property, was used as a stabilizer for preparation of Pd nanoparticle catalyst through hydrogen reduction of Pd?OAc?₂. The ILPEG1000-stabilized Pd nanoparticles and the mixture of toluene and n-heptane can form and realize thermoregulated phase-separable catalysis ?TPSC?. The principle of TPSC is that at room temperature, the lower ILPEG1000 phase containing Pd nanoparticles and the upper organic phase composed of toluene and n-heptane are immiscible, when the temperature gradually elevates and surpases the CST, the biphasic system mingles to a single phase, then the reaction can react in a single phase. When the temperature of reaction system decreases to room temperature, the system becomes original biphase again. The catalyst can be separated from the reaction system easily through simple phase separation and reused directly in the next reaction run.ILPEG1000-stabilized Pd nanoparticles were employed as catalyst for the carbonylative Sonogashira coupling of aryl iodides. We took the carbonylative Sonogashira coupling of iodobenzene with phenylacetylene as template reaction. Under the optimal reaction conditions: Iodobenzene/Pd= 500 ?molar ratio?, TPP/Pd= 2 ?molar ratio?, T= 120 ?, t= 6 h, PCO= 1 MPa, TEA as base, the iodobenzene's conversion was more than 99% and the selectivity for diphenylpropynone was 97%. The catalyst could be reused for 8 times without evident loss in activity and selectivity. The turnover number ?TON? was 4,215.ILPEG1000-stabilized Pd nanoparticles were employed as catalyst for the aminocarbonylation of aryl iodides. We took the aminocarbonylation of iodobenzene with diethylamine as template reaction. Under the optimal reaction conditions:Iodobenzene/Pd= 200 ?molar ratio?, T= 120 ?,/= 8 h, PCO= 1 MPa, TEA as base, the iodobenzene's conversion was more than 99% and the selectivity for N,N-dimethylbenzamide was 97%. The catalyst could be reused for 5 times without evident loss in activity and selectivity. The TON was 1,104.