We aimed to develop new effective catalysts for the synthesis of propylene carbonate from propylene oxide and carbon dioxide. A kind of Mx+LClx coordination complex was fabricated based on the chelating tridentate ligand 2,6-bis[1-(phenylimino)ethyl] pyridine (L). The obtained products were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. It was found that the catalytic activity of the complexes with different metal ions, the same ligand differed and co-catalyst, where the order of greatest to least catalytic activity was 2 > 3 > 1. The catalytic system composed of complex 2 and DMAP proved to have the better catalytic performance. The yields for complex 2 systems was 86.7% under the reaction conditions of 100 °C, 2.5 MPa, and 4 h. The TOF was 1026 h-¹ under the reaction conditions of 200 °C, 2.5 MPa, and 1 h. We also explored the influence of time, pressure, temperature, and reaction substrate concentration on the catalytic reactions. A hypothetical catalytic reaction mechanism is proposed based on density functional theory (DFT) calculations and the catalytic reaction results.
Abstract A series of Ti/Li/Al ternary layered double hydroxides (TiLiAl-LDHs) with different Ti:Li:Al molar ratios were prepared by a coprecipitation method for photocatalytic CO 2 reduction. It was demonstrated that the contents of anions between the layers of Ti/Li/Al-LDHs greatly determined the photocatalytic activity for CO 2 reduction. With Ti:Li:Al molar ratios optimized to be 1:3:2, the largest contents of $${{\bf{CO}}}_{{\bf{3}}}^{{\bf{2}}}$$ CO32 − anion and hydroxyl group were obtained for the Ti 1 Li 3 Al 2 -LDHs sample, which exhibited the highest photocatalytic activity for CO 2 reduction, with CH 4 production rate achieving 1.33 mmol h −1 g −1 . Moreover, the theoretical calculations show that Ti 1 Li 3 Al 2 -LDHs is a p-type semiconductor with the narrowest band gap among all the obtained TiLiAl-LDHs. After calcined at high temperatures such as 700 °C, and the obtained TiLiAl-700 sample showed much increased photocatalytic activity for CO 2 reduction, with CH 4 production rate reaching about 1.59 mmol h −1 g −1 . This calcination induced photocatalytic enhancement should be related to the cystal structure transformation from hydrotalcite to mixed oxides containing high reactive oxygen species for more efficient CO 2 reduction.
Based on the joint paternal allele probability, the joint genotype probability about related individuals is derived. Two rational pedigrees are discussed and the corresponding joint genotype probabilities about related people are given. The methods can be used to handle more general problems. Two case examples are given for demonstration in the kinship testing.
Based on the ligand H2dpPzda (1), a novel cobalt complex [Co(H2dpPzda)(NCS)2]·CH3OH(2) has been synthesized and characterized. The Complex 2 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 29,200 h−1. The catalytic system also showed broad substrate scope of epoxide. Additionally, the catalyst could be recycled to maintain the integrity of the structure and remained equal to the level of its catalytic activity even after seven catalytic rounds. Additionally, a possible catalytic mechanism was proposed due to the high catalytic activity which might be owing to the synergism of Lewis acidic metal centers and N group.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Recently, ionic liquids (ILs) are known as potential green materials with unique properties such as low vapor pressure, high thermal stability, and excellent solution ability of organic or inorganic materials. In this paper, the quantitative structure property relationship (QSPR) models of 111 common imidazole-based ionic liquids were established by using CORrelation and Logic (CORAL) software to predict the melting point of imidazole-based ionic liquids. The molecular structure of imidazole-based ionic liquids is represented by simplified molecular input line entry system (SMILES). The balance of correlations and the classic scheme were compared by building the models of QSPR based on the Mont Carlo method. SMILES descriptors were randomly divided into three data sets, and the results showed that the model of classic scheme was more reliable. The best correlation coefficient (R2) values for the validation sets of two models were 0.9512 and 0.9219, respectively. Their best internal validated correlation coefficient (Q2) values were 0.9414 and 0.8961, respectively.
Abstract A PPC‐dodecyl glucoside (PPC‐APG) polymer was synthesized by the terpolymerization of carbon dioxide (CO 2 ), propylene oxide (PO), and the bio‐based monomer APG for the first time. The thermal stability and mechanical properties of PPC‐APG were significantly improved compared with those of conventional polypropylene carbonate (PPC), and its glass transition temperature ( T g ) was increased by 14°C compared with that of PPC. The 5% heat loss temperature ( T d,−5% ) and total heat loss temperature ( T d,max ) of PPC‐APG were increased by 89.1 and 92.1°C, respectively, compared with those of PPC. The tensile strength of PPC‐APG was increased to 25.6 MPa, its elongation at break was decreased to 125.1%, and its thermal elongation and permanent deformation were reduced to 97.2% and 62.9%, respectively, which improved the processability of the material. In addition, the introduction of bio‐based monomers also rendered PPC‐APG functional, and its surface tension reached a maximum of 61.3 mN/m at a concentration of 0.05 g/mL, with a good degradability. The higher surface tension and enhanced degradability of PPC‐APG indicate its potential for application as a plastic printing substrate.
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