27797-53-1Relevant articles and documents
Efficient catalytic conversion of terminal/internal epoxides to cyclic carbonates by porous Co(ii) MOF under ambient conditions: Structure-property correlation and computational studies
Parmar, Bhavesh,Patel, Parth,Pillai, Renjith S.,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Suresh, Eringathodi
, p. 2884 - 2894 (2019)
A mixed ligand three-dimensional neutral porous framework, {[Co(OBA)(L)]xG}n (CoMOF-1) (H2OBA = 4,4′-oxybis(benzoic acid); L = (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide; G = DMF, EtOH, MeOH, H2O), was successfully synthesized via a hydrothermal and reflux method. The activated MOF (CoMOF-1′) not only showed good affinity toward CO2 molecules, but also exhibited a good catalytic performance for CO2 conversion with a variety of terminal and internal epoxides. Grand Canonical Monte Carlo (GCMC) simulation proved the strong interactions of CO2 molecules with the amide functional groups of the MOF. The Lewis acidity of the Co(ii) centers endowed by the weakly chelated carboxylate from the OBA ligand and Lewis basicity originating from the acylamide functionality of the pyridyl-based Schiff base ligand L favored the efficient solvent-free cycloaddition reaction of CO2 with different epoxides. Strikingly, CoMOF-1′ exhibited good catalytic efficiency for CO2 coupled with various terminal epoxides at ambient temperature and pressure (1 bar, 60 °C, 12 h) and with a variety of internal epoxides at moderate reaction conditions (30 bar, 100 °C, and 8 h) with good yield and recyclability. Further, the binary heterogeneous catalyst showed good chemical stability, easy separation and recyclability (6 cycles) without a noticeable decrease in activity. To the best of our knowledge, this is the first investigation on a neutral porous MOF as a potential heterogeneous solvent-free catalyst toward CO2 utilization for internal epoxide under moderate reaction conditions. Based on the structural evidence, a plausible mechanism for the cycloaddition reaction was proposed, which is further reinforced by the relative energy of each stage obtained from periodic Density Functional Theory (DFT) calculations.
CO2 fixation by cycloaddition of mono/disubstituted epoxides using acyl amide decorated Co(II) MOF as a synergistic heterogeneous catalyst
Patel, Parth,Parmar, Bhavesh,Pillai, Renjith S.,Ansari, Amamudin,Khan, Noor-ul H.,Suresh, Eringathodi
, (2020)
Dual ligand 3D MOF {[Co(BDC)(L)]·2H2O.xG}n (CoMOF-2; G = guest) was synthesized via simple room temperature stirring method. Bulk Phase purity of CoMOF-2 was assessed by various physicochemical methods including X‐ray diffraction (XRD). CO2 adsorption isotherms indicate that activated CoMOF-2 is efficient in CO2 uptake, which has been utilized for the CO2-Epoxide cycloaddition. The catalytic ability of CoMOF-2 as a binary catalyst revealed excellent results for variety of monosubstituted epoxide under solvent‐free conditions (1 bar/40 °C/12 h). Interestingly CoMOF-2/KI also showed great potential as a heterogeneous catalyst for disubstituted epoxide (10 bar/120 °C/24 h) with high yields/selectivity. The catalytic efficiency of the present investigation for scantly explored disubstituted epoxide is better/on par with the earlier reports and the recyclability of the catalyst is an added advantage. Probable mechanism for the catalytic reaction is deduced and verified the representative energy profile for cycloaddition of CO2-Cyclohexane oxide (CHO) by DFT calculation.
A Strained Ion Pair Permits Carbon Dioxide Fixation at Atmospheric Pressure by C-H H-Bonding Organocatalysis
Xu, Jiaxi,Xian, Anmei,Li, Zhenjiang,Liu, Jingjing,Zhang, Zhihao,Yan, Rui,Gao, Luoyu,Liu, Bo,Zhao, Lili,Guo, Kai
, p. 3422 - 3432 (2021/02/27)
The cycloadditions of carbon dioxide into epoxides to afford cyclic carbonates by H-bond donor (HBD) and onium halide (X) cocatalysis have emerged as a key strategy for CO2 fixation. However, if the HBD is also a halide receptor, the two will quench each other, decreasing the catalytic activity. Here, we propose a strained ion pair tris(alkylamino)cyclopropenium halide (TAC·X), in which TAC repels X. TAC possesses a positively charged cyclopropenium core that makes the vicinal C-H or N-H a nonclassical HBD. The interionic strain within TAC·X makes TAC a more electrophilic HBD, allowing it to activate the oxygen of the epoxide and making X more nucleophilic and better able to attack the methylene carbon of the epoxide. NMR titration spectra and computational studies were employed to probe the mechanism of the cycloaddition of CO2 to epoxides reactions under the catalysis of TAC·X. The 1H and 13C{1H}NMR titration spectra of the catalyst with the epoxide substrate unambiguously confirmed H-bonding between TAC and the epoxide. DFT computational studies identified the transition states in the ring-opening of the epoxide (TS1) and in the ring-closure of the cyclic carbonate (TS2).
One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: Theoretical evidence for an asynchronous concerted pathway
Demir, Esra,Sari, Ozlem,?etinkaya, Yasin,Atmaca, Ufuk,Erdem, Safiye Sa?,?elik, Murat
, p. 1805 - 1819 (2020/11/07)
The one-pot reaction of chlorosulfonyl isocyanate (CSI) with epoxides having phenyl, benzyl and fused cyclic alkyl groups in different solvents under mild reaction conditions without additives and catalysts was studied. Oxazolidinones and five-membered cyclic carbonates were obtained in ratios close to 1:1 in the cyclization reactions. The best yields of these compounds were obtained in dichloromethane (DCM). Together with 16 known compounds, two novel oxazolidinone derivatives and two novel cyclic carbonates were synthesized with an efficient and straightforward method. Compared to the existing methods, the synthetic approach presented here provides the following distinct advantageous: being a one-pot reaction with metal-free reagent, having shorter reaction times, good yields and a very simple purification method. Moreover, using the density functional theory (DFT) method at the M06-2X/6-31+G(d,p) level of theory the mechanism of the cycloaddition reactions has been elucidated. The further investigation of the potential energy surfaces associated with two possible channels leading to oxazolidinones and five-membered cyclic carbonates disclosed that the cycloaddition reaction proceeds via an asynchronous concerted mechanism in gas phase and in DCM.
