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961.
962.
二氧化碳既是温室气体的主要成分又是储量丰富且可再生的碳资源,研究二氧化碳的化学转化和利用有着重要意义。基于二氧化碳与催化剂的弱相互作用以及催化活化原理,通过采用环境友好的反应介质(如高密度二氧化碳、聚乙二醇等)及催化剂的设计、分离和循环利用等策略,设计并合成了单组分和双组分的功能化高效催化剂用于合成有机碳酸酯、脲、噁唑啉酮和喹唑啉二酮类化合物,并相应建立了具有重要工业应用价值的合成新方法以及环境友好的新工艺。以二氧化碳为合成子的精细化工中间体合成不但丰富了有机化学的合成方法学,也为解决日渐严重的环境问题提供潜在的新方法。在此,对本课题组近二年来在二氧化碳化学尤其是二氧化碳催化转化方法方面的研究成果做一小结。 相似文献
963.
964.
965.
Brφnsted酸性离子液体催化合成长链脂肪酸甲酯 总被引:2,自引:0,他引:2
本文合成了以1-丁基-3-甲基咪唑为阳离子,HSO4-、H2PO4-和BF4-为阴离子的Brφnsted酸性离子液体,并以长链脂肪酸与甲醇的酯化反应考察了这些Brφnsted酸性离子液体的催化性能。实验结果表明,1-丁基-3-甲基咪唑硫酸氢根鎓盐([bmim][HSO4])离子液体具有很高的催化活性,当n(醇)∶n(酸)∶n(离子液体)=6∶1∶0.25,反应温度为70℃,不分水酯化反应2h,长链脂肪酸甲酯的产率可达到93.4%以上,选择性达到100%;且产物酯与离子液体分离容易;离子液体经干燥处理后可以循环使用5次以上,催化活性没有明显降低。 相似文献
966.
967.
The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD(T)//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. One consists of two steps: (1) the two reactants (R1, R2) firstly form a four-membered ring intermediate (INT4) through a barrier-free exothermic reaction of 585.9 kJ/mol; (2) Then intermediate (INT4) isomerizes to CH3-transfer product (P4.1) via a transition state (TS4.1) with energy barrier of 5.3 kJ/mol. The other is as follows: on the basis of intermediate (INT4) created between R1 and R2, intermediate (INT4) further reacts with acetone (R2) to form the intermediate (INT5) through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate (INT5) isomerizes to a silicic bis-heterocyclic product (P5) via a transition state (TS5), for which the barrier is 54.9 kJ/mol. The presented rule of this reaction: the [2+2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate (INT4); The unsaturated property of C atom from carbene in the four-membered ring intermediate (INT4) results in the generation of CH3-transfer product (P4.1) and silicic bis-heterocyclic compound (P5). 相似文献
968.
LI Na MA Cheng-Bing WANG Mei ZHOU Rong-Wei HU Ming-Qiang CHEN Chang-Neng 《结构化学》2010,29(11):1731-1735
A new manganese compound [Mn8(tmp)2(Htmp)4((CH3)3CCO2)4(py)2Cl2]·2py (1·2py, H3tmp = 1,1,1-tri(hydroxymethyl)propane, py = pyramid) has been synthesized and its structure was characterized by IR, elemental analysis and X-ray diffraction. Compound 1 belongs to the triclinic system, space group P1 with a = 13.378(5), b = 14.334(5), c = 15.012(6) , α = 107.637(5), β = 95.635(3), γ = 92.825(4)°, V = 2720.7(17) 3, Z = 1, C76H124N4O26Cl2Mn8, Mr = 2022.23, Dc = 1.234 Mg/m3, μ = 1.007 mm-1, F(000) = 1052, T = 293(2) K, the final R = 0.0755 and wR = 0.2163 for all 6463 observed reflections (I > 2σ(I)). X-ray analysis shows that the core of 1 contains a [Mn8] mixed-valence rod-like unit consisting of six edge-sharing triangles (Mn3), each of which is bridged by a μ3-oxygen atom. 相似文献
969.
The possible reaction mechanisms of FeST(6∑+and 4Ф states)with COS in the gas phase have been studied by using density functional theory at the B3LYP/TZVP and B3LYP/6-311+G*levels:the O/S exchange reaction(FeS++COS=FeO++CS2),O-transfer reaction(FeS++COS=FeSO++CS)and S-transfer reaction(FeS++COS=FeS2++CO).The calculation results show that the large barriers(205.7 and 310.1 kJ/mol)and the small probability of forming the preceding intermediate indicate a much lower efficiency of the O/S exchange and the O-transfer reactions and their corresponding products may not be observed experimentally.FeS2+,the product of S-transfer reaction,is predicted to be the main product.But the reactivity of the 6∑+ground state of FeS+toward COS is lower than the earlier transition metal sulfide cations MS+(M=Sc,Ti and V),although it has more reaction channels and different mechanisms. 相似文献
970.
Solvothermal reaction of [WS4]2-with CuCN and trithiocyanuric acid(L1) in orga-nic solvents gave rise to a new W/Cu/S polymer with a 2D anionic network,namely [Et4N]2[WS4Cu3(C3N3S3H1.5)2](1).The anionic layer of 1 is constructed by the T-shaped {WS4Cu3} subunits as nodes and L1 as linkers and features a(4,4) topology.Both 1 and its isomorphous compound [Et4N]2[MoS4Cu3(C3N3S3H1.5)2](2) have been fully characterized by X-ray crystal analysis,IR and microanalyses.Compounds 1 and 2 show optical transitions with band gaps of 2.17 and 1.84 eV,respectively. 相似文献