Search

• Co-Salen complexes containing different groups and bearing potassium iodide (KI) complexed with crown ether (K@SCs) were prepared. • Salen derivative organic polymer as heterogeneous catalyst for CO 2 cycloaddition reaction. • Alkali metal halides and Lewis acids have good synergistic effects in catalytic reactions. Metallosalen presents very important applications in both homogenous and heterogeneous catalysis. Correspondingly, porous polymeric metallosalen combined with the performance of organometallics and heterogeneous polymers possess potential in CO 2 fixation reactions. Herein, a family collection of K@SCs were conceived and obtained by combining cobalt-salen complexes with different groups and diaminobenzene-18-crown-6 complexed with KI, which allows multiphase catalytic immobilization of CO 2 to epoxides. Catalyst K@SC-3 can fix CO 2 into a variety of substituted epoxides in >90% yields to the corresponding cyclic carbonates in co-catalyst-free and solvent-free conditions. Furthermore, K@SC-3 can be recovered and reused at least six times by simple centrifugal separation, demonstrating superior stability. The kinetics experiments were also carried out at varied temperatures catalyzed by K@SC-3. It is concluded that a first-order equation of epoxide was proved and the activation energy was calculated to be 27.13 KJ/mol. [Display omitted] [ABSTRACT FROM AUTHOR]

• The Tröger base analogue coordinated with potassium iodide and containing crown ether CATB-KI was fabricated. • The acidified CATB-KIs shown high catalytic efficiency to cyclic carbonates. • The synergistic mechanism has been proved in terms of experimental results and calculation of dynamics. Tröger's bases (TB) containing two steric nitrogen atoms, are alternated as building block for constructing molecular acceptors to form covalent bonds with acids, making TB a promising catalyst. Herein, TB analogs fabricated with crown ethers were knitted by condensation reaction and combined with potassium iodide as a brand-new catalytic system (CATB-KIs), which were characterized using FT-IR, 13C CP MAS NMR, SEM, TGA, and XPS spectroscopy respectively. The generated CATB-KIs exhibited excellent performance for CO 2 fixation reaction with epoxides to produce cyclic carbonates under mild conditions, and the catalytic activity could be further improved by coordinating with acids beforehand, in which HBr performs fascinated activity. After 12 h, the corresponding cyclic carbonate from epichlorohydrin with 95.1% yield was detected at mild conditions with solvent-free in the presence of CATB-KI-2 and HBr. A series of terminal epoxides were converted into desired cyclic carbonates with desirable yields. The catalyst could be recovered successfully and reused six times without significant loss of activity. Finally, dynamics study on catalytic mechanism has been accomplished and the activated energy was calculated as 72.1 kJ/mol. A synergistic catalytic mechanism of hydrogen bonding and I anion has been proposed to account for the excellent catalytic activity of this catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]