离子液体型电解质在储能材料、电化学沉积等方面具有重要的研究意义。从酯基异构化的角度出发,设计合成了互为异构体的含酯基吡啶类离子液体,丁酸甲酯基吡啶六氟磷酸盐[n-C_4MePy][PF_6](记IL1)和异丙酸乙酯基吡啶六氟磷酸盐[i-C_3EAPy]...离子液体型电解质在储能材料、电化学沉积等方面具有重要的研究意义。从酯基异构化的角度出发,设计合成了互为异构体的含酯基吡啶类离子液体,丁酸甲酯基吡啶六氟磷酸盐[n-C_4MePy][PF_6](记IL1)和异丙酸乙酯基吡啶六氟磷酸盐[i-C_3EAPy][PF_6](记IL2)。对离子液体(记IL)-有机溶剂体系的电导性能进行研究,在0.0005~0.01 mol·L^(-1)浓度范围内,酯基异构化对二元体系的电导率影响相对较大。与IL2-有机溶剂体系相比,IL1-CH_3OH的电导率约为IL2-CH_3OH的2倍,而IL1-CH_3CN和IL1-(CH_3)_2NOH的电导率相对较小。同时在相同条件下,其不同溶剂体系的电导率为κ_(甲醇)>κ_(乙腈)>κ_(N,N二甲基甲酰胺),这可能与溶剂的介电常数大小有关。进一步研究表明,离子液体异构体(IL)-有机溶剂体系的导电行为均符合阿伦尼乌斯行为,在N,N-二甲基甲酰胺溶剂体系中,离子液体的酯基异构使得体系的电导活化能变化较为显著。与IL1-(CH_3)_2NOH相比,IL2-(CH_3)_2NOH的电导活化能减小了8.454 k J·mol^(-1),这可能是由于IL2与溶剂分子上的基团相互吸引力增强,导致了其体系活化能减小。最后对离子液体异构体的热稳定性分析表明,与IL1的分解温度487.48℃相比,酯基异构化使IL2的热分解温度降低了301.77℃。展开更多
A series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized io...A series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized ionic liquid and perfluo- ropolyethers （PFPE）. The morphology and chemical composition of the worn scars were analyzed by scanning electron mi- croscopy and X-ray photoelectron spectroscopy, respectively, and the possible lubrication mechanism of ILs was discussed. As a result, all ILs demonstrated a better lubricity and a much higher load-carrying capacity than PFPE used as lubricants for the steel-steel tribomates system. The functionalized ILs with ester-group showed slightly worse friction reducing abil- ity than their nonfunctionalized counterparts at relatively lower loads owing to their higher viscosity, but then exhibited better antiwear ability because the ester group they contained had not only physical but also strong chemical reactions with the freshly exposed steel surface and formed chemical adsorption boundary films on the worn surface during friction pro- cess. Under high loads, some triboehemical reactions took place between the active elements, such as fluorine which were released from the ILs, and fresh metal surfaces of rubbing pairs to form the admixture reaction films, which were mainly composed of ferric fluoride mixed with ferric oxide, leading to lower friction coefficients and good wear resistance.展开更多
In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing gro...In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing groups,commonly occurring functional groups,and easily removable auxiliaries,have been found to be efficient and practical for C–H activation reactions.This mini-review contains examples of recent research advances on transition-metal-catalyzed SP2 C–H functionalization via weak coordination,using Ru,Rh,and Pd.A number of weakly coordinating functional groups(e.g.,ketone,ester,carbamate,tertiary amide,ether,thioether,alcohol,and some others)are covered.As the field of transition-metal-catalyzed C–H functionalization continues to develop and more synthetically useful chemo-,regio-,and enantioselective reactions catalyzed by transition metal via weak coordination are discovered,this promising and attractive strategy will play a more important role in modern organic synthesis.展开更多
文摘离子液体型电解质在储能材料、电化学沉积等方面具有重要的研究意义。从酯基异构化的角度出发,设计合成了互为异构体的含酯基吡啶类离子液体,丁酸甲酯基吡啶六氟磷酸盐[n-C_4MePy][PF_6](记IL1)和异丙酸乙酯基吡啶六氟磷酸盐[i-C_3EAPy][PF_6](记IL2)。对离子液体(记IL)-有机溶剂体系的电导性能进行研究,在0.0005~0.01 mol·L^(-1)浓度范围内,酯基异构化对二元体系的电导率影响相对较大。与IL2-有机溶剂体系相比,IL1-CH_3OH的电导率约为IL2-CH_3OH的2倍,而IL1-CH_3CN和IL1-(CH_3)_2NOH的电导率相对较小。同时在相同条件下,其不同溶剂体系的电导率为κ_(甲醇)>κ_(乙腈)>κ_(N,N二甲基甲酰胺),这可能与溶剂的介电常数大小有关。进一步研究表明,离子液体异构体(IL)-有机溶剂体系的导电行为均符合阿伦尼乌斯行为,在N,N-二甲基甲酰胺溶剂体系中,离子液体的酯基异构使得体系的电导活化能变化较为显著。与IL1-(CH_3)_2NOH相比,IL2-(CH_3)_2NOH的电导活化能减小了8.454 k J·mol^(-1),这可能是由于IL2与溶剂分子上的基团相互吸引力增强,导致了其体系活化能减小。最后对离子液体异构体的热稳定性分析表明,与IL1的分解温度487.48℃相比,酯基异构化使IL2的热分解温度降低了301.77℃。
基金the Natural Science Foundation Project of CQ CSTC, 2010BB0201
文摘A series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized ionic liquid and perfluo- ropolyethers （PFPE）. The morphology and chemical composition of the worn scars were analyzed by scanning electron mi- croscopy and X-ray photoelectron spectroscopy, respectively, and the possible lubrication mechanism of ILs was discussed. As a result, all ILs demonstrated a better lubricity and a much higher load-carrying capacity than PFPE used as lubricants for the steel-steel tribomates system. The functionalized ILs with ester-group showed slightly worse friction reducing abil- ity than their nonfunctionalized counterparts at relatively lower loads owing to their higher viscosity, but then exhibited better antiwear ability because the ester group they contained had not only physical but also strong chemical reactions with the freshly exposed steel surface and formed chemical adsorption boundary films on the worn surface during friction pro- cess. Under high loads, some triboehemical reactions took place between the active elements, such as fluorine which were released from the ILs, and fresh metal surfaces of rubbing pairs to form the admixture reaction films, which were mainly composed of ferric fluoride mixed with ferric oxide, leading to lower friction coefficients and good wear resistance.
基金supported by the National Basic Research Program of China(2011CB965300)the National Natural Science Foundation of China(21142008,21302106)Tsinghua University 985 Phase II Funds,and the Tsinghua University Initiative Scientific Research Program
文摘In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing groups,commonly occurring functional groups,and easily removable auxiliaries,have been found to be efficient and practical for C–H activation reactions.This mini-review contains examples of recent research advances on transition-metal-catalyzed SP2 C–H functionalization via weak coordination,using Ru,Rh,and Pd.A number of weakly coordinating functional groups(e.g.,ketone,ester,carbamate,tertiary amide,ether,thioether,alcohol,and some others)are covered.As the field of transition-metal-catalyzed C–H functionalization continues to develop and more synthetically useful chemo-,regio-,and enantioselective reactions catalyzed by transition metal via weak coordination are discovered,this promising and attractive strategy will play a more important role in modern organic synthesis.
