Computer‐Assisted Design of Imidazolate‐Based Ionic Liquids for Improving Sulfur Dioxide Capture,Carbon Dioxide Capture,and Sulfur Dioxide/Carbon Dioxide Selectivity

A new strategy involving the computer‐assisted design of substituted imidazolate‐based ionic liquids (ILs) through tuning the absorption enthalpy as well as the basicity of the ILs to improve SO₂ capture, CO₂ capture, and SO₂/CO₂ selectivity was explored. The best substituted imidazolate‐based ILs as absorbents for different applications were first predicted. During absorption, high SO₂ capacities up to ≈5.3 and 2.4 mol mol_IL⁻¹ could be achieved by ILs with the methylimidazolate anions under 1.0 and 0.1 bar (1 bar=0.1 MPa), respectively, through tuning multiple N ⋅⋅⋅ S interactions between SO₂ and the N atoms in the imidazolate anion with different substituents. In addition, CO₂ capture by the imidazolate‐based ILs could also be easily tuned through changing the substituents of the ILs, and 4‐bromoimidazolate IL showed a high CO₂ capacity but a low absorption enthalpy. Furthermore, a high selectivity for SO₂/CO₂ could be reached by IL with 4,5‐dicyanoimidazolate anion owing to its high SO₂ capacity but low CO₂ capacity. The results put forward in this work are in good agreement with the predictions. Quantum‐chemical calculations and FTIR and NMR spectroscopy analysis methods were used to discuss the SO₂ and CO₂ absorption mechanisms.     

Mode Specificity,Bond Selectivity,and Product Energy Disposal in X + CH4/CHD3 (X=H,F, O(3P), Cl,and OH) Hydrogen Abstraction Reactions: Perspective from Sudden Vector Projection Model

Reactions between methane and various radicals have become the workhorse in our understanding of mode specificity and bond selectivity in bimolecular reactions. In this work, the recently proposed Sudden Vector Projection (SVP) model is used to gain insight into the existing experimental and theoretical data on these reactions. The SVP model attributes mode specificity and bond selectivity to the coupling of reactant modes/bonds with the reaction coordinate at the transition state. In the sudden limit, the strength of the coupling can be simply computed by projecting the corresponding reactant normal mode vector onto that of the imaginary frequency mode at the saddle point. In addition, the SVP model can be used to predict energy disposal in the products, thanks to microscopic reversibility. It is shown that most of the mode‐specific and bond‐selective chemistry in X + CH₄/CHD₃ (X=H, F, O(³P), Cl, and OH) reactions can be reasonably understood with this simple model.     

Silica-Functionalized CuI: An Efficient and Selective Catalyst for N-Benzylation,Allylation, and Alkylation of Primary and Secondary Amines in Water

Silica-functionalized CuI has been reported as an efficient and selective catalyst for the selective mono-N- and N,N-dibenzylation, allylation, and alkylation of primary amines with benzylic, allylic, and alkyl halides using NaOH as base in aqueous medium. By changing the reaction temperature, mono- or di-benzylation, allylation, or alkylation could be achieved in good yield and selectivity. Secondary amines have also been benzylated, allylated, and alkylated under similar conditions. SiO₂-CuI has been characterized by Fourier transform–infrared, atomic absorption spectrometry, thermalgravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and found to be highly selective and recyclable under the reaction conditions.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

P-Al/NaX结构和酸碱性位调控对甲苯甲醇侧链烷基化性能影响

采用水热法原位合成了P-Al/NaX催化剂,然后通过浸渍NaOH对其进行酸碱性调控,并探究了它在甲苯甲醇侧链烷基化反应中的催化性能。结合X射线衍射（XRD）、X射线光电子能谱（XPS）、N₂吸附-脱附等表征及催化活性数据发现,原位负载P、Al后,合成的磷铝硅酸盐（Na₁₃Al₂₄Si₁₃P₁₁O₉₆·H₂O）结构展现出较好的甲苯甲醇侧链烷基催化活性;随着NaOH负载量的增加,乙苯和苯乙烯的选择性呈先上升后下降的趋势,当负载质量分数为9%的NaOH时,苯乙烯选择性为45.84%,乙苯和苯乙烯的收率之和达到63.08%。这可能是由于NaOH的负载有利于催化剂表面碱性的提高和酸性的降低,而高的强碱性位和弱酸性位数量有利于甲苯甲醇侧链烷基化反应的进行。     

NiMo 催化剂上MoS2 形貌与其DBT 加氢脱硫选择性的关系

制备了两个系列不同镍钼负载量的NiMo 催化剂,并用X 衍射、N2 物理吸附和透射电镜进行了表征。以二苯并噻吩
为模型硫化物,在高压固定床微型反应器上对该NiMo 催化剂的加氢脱硫性能进行了评价,研究了MoS2 形貌与催化剂加氢脱
硫选择性之间的关系。结果表明,镍钼负载量对MoS2 形貌有明显的影响。Mo18Ni4 催化剂(含18% MoO3 和4% NiO)上
MoS2 呈多级层状结构,具有较高的加氢脱硫活性和优异的加氢脱硫选择性。加氢选择性与催化剂上活性组分MoS2 的堆积层
数相关联呈很好的线性关系;堆积层数越多,其加氢选择性也越高。     

Rh/ZnO-Al2O3催化剂用于巴豆醛选择性加氢（英文）

Gas phase hydrogenation of crotonaldehyde was performed over 1 wt% Rh/ZnO-Al2O3 catalysts with various Zn/Rh atomic ratios. Monometallic Rh/Al2O3 was also prepared for comparison. The samples were prepared by the successive impregnation of Al2O3 with chlo-ride precursors of zinc and rhodium. The solids have been characterized by H2 chemisorption,temperature-programmed reduction,scanning electron microscopy,and cyclohexane dehydrogenation. Their catalytic behaviour in the gas phase crotonaldehyde hydrogenation reaction after reduction treatment in flowing hydrogen at 723 K was investigated. The relationship between catalytic activity,selectivity for crotyl alcohol,and physicochemical properties of the catalysts was examined. Results obtained showed that the presence of Zn clearly promotes the hydrogenation of the carbonyl bond. The catalyst with Zn/Rh atomic ratio of 5 displayed good catalytic stability and the highest selectivity for crotyl alcohol(70%) along with alloy formation.     

Striking alkenol versus allenol reactivity: metal-catalyzed chemodifferentiating oxycyclization of enallenols

An efficient chemodivergent metal-controlled methodology for the generation of different highly functionalized oxygen heterocycles from common enallenol substrates has been developed. Chemoselectivity control in the O-C functionalization of an enallenol can be achieved through the choice of catalyst: AuCl(3), PdCl(2), and [PtCl(2)(CH(2)=CH(2))](2) exclusively afford dihydrofurans through selective activation of the allenol moiety, whereas FeCl(3) solely gives tetrahydrofurans or tetrahydropyrans through selective activation of the alkenol moiety. We have also shown that a combination of metal-mediated hydroalkoxylation and allenic aminocyclization reactions can lead to a useful preparation of the tetrahydrofuro[3,2-b]piperidine core of the antimalarial alkaloid isofebrifugine. These divergent heterocyclization reactions have been developed experimentally and additionally, their mechanisms have been investigated by a theoretical study.     

DFT study on the selective oxidation of vinyl chloride on different metal surfaces

Selective epoxidation of vinyl chloride on Ag(111), Pt(111) and Rh(111) with pre-adsorbed atomic oxygen has been studied by density functional theory (DFT) calculation with the periodic slab model. The reaction energies and activation energies of the epoxidation reaction are determined. Because of the asymmetry of vinyl chloride, three competitive reaction pathways are investigated. The results indicate that the most possible reaction pathway is pathway III. Compared the activation energies of the epoxidation reaction on Ag(111), Pt(111) and Rh(111), it is obvious that the reaction via OMMC(3) on Ag(111) is the most possible process. However, the selectivity to the target product over Ag(111) is the lowest among the three metals. The results also indicate that the formation of chloroacetaldehyde is more favorable than that of chloroepoxide.     

Contributions to reversed-phase column selectivity. I. Steric interaction

In reversed-phase chromatography (RPC), the restricted retention of "bulky" solutes can occur in one of two ways, giving rise to either "shape selectivity" or "steric interaction." Starting with data for 150 solutes and 167 monomeric type-B alkylsilica columns, the present study examines the steric interaction process further and compares it with shape selectivity. The dependence of column hydrophobicity and steric interaction on column properties (ligand length and concentration, pore diameter, end-capping) was determined and compared. The role of the solute in steric interaction was found to be primarily a function of solute molecular length, with longer solutes giving increased steric interaction. We find that there are several distinct differences in the way shape selectivity and steric interaction are affected by separation conditions and the nature of the sample. Of particular interest, steric interaction exhibits a maximum effect for monomeric C(18) columns, and becomes less important for either a C(1) or C(30) column; shape selectivity appears unimportant for monomeric C(1)-C(18) columns at ambient and higher temperatures, but becomes pronounced for C(30) - as well as polymeric columns with ligands ≥C(8). One hypothesis is that shape selectivity involves the presence or creation of cavities within the stationary phase that can accommodate a retained solute (a primarily enthalpic process), while steric interaction mainly makes greater use of spaces that pre-exist the retention of the solute (a primarily entropic process). The related dependence of hydrophobic interaction on column properties was also examined.