The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found ...The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found that its retention rate of mechanical properties is far higher than that of the control sample. The results of thermogravimetric analysis show that its thermal-decomposing temperature rises largely. The analysis of oxidation mechanisms indicates that the main reasons for thermal oxidation resistance are that rare earth elements are of the utility to discontinue autoxidation chain reaction and that the formed complex structure has steric hindrance effect on oxidation.展开更多
Long-alkyl tail triphenylene （TP） side-chain liquid crystalline polymers （SCLCPs） with different spacer length （P-m-TP, m = 2, 3, 4, 6, 8, which is the number of carbon atom in the flexible alkyl spacers） have b...Long-alkyl tail triphenylene （TP） side-chain liquid crystalline polymers （SCLCPs） with different spacer length （P-m-TP, m = 2, 3, 4, 6, 8, which is the number of carbon atom in the flexible alkyl spacers） have been successfully synthesized via free radical polymerization. The differential scanning calorimetry （DSC）, polarized light microscopy （POM）, ultraviolet-visible spectroscopy （UV- Vis）, wide-angle X-ray diffraction （WAXD） and small-angle X-ray scattering （SAXS） measurements were performed to investigate the influence of multiple effects on the self-organization behaviors of P-m-TP, including steric effect, decoupling effect and π-π stacking effect. The experimental results revealed that P-m-TP （m = 2, 3, 4） formed the columnar phase which was developed by the TP moieties and the main chain as a whole, suggesting that the side-chains had strong steric effect even though the number of spacer length （m） exceeded 4. In addition, the clearing points （Tis） of the polymers were above 300 ℃. When m = 6 and 8, the polymers displayed hexagonal columnar phase and exhibited the low Tis （91 and 80 ℃ respectively）, originating from the self-assembly of triphenylene due to the decoupling effect and π-π stacking effect. This work offers a viable and inspiring pathway to control the phase transition temperature and phase structure ofTP SCLCPs via simply tailoring the spacer length and increasing the alkyl tail length of TP.展开更多
<正> The steric structure and solvent effect of 6,6-dialkylfulvenes in reaction with α-naphthyllithium is studied. It is found for the first time that organolithium causes fulvenes to undergo reductive coupling...<正> The steric structure and solvent effect of 6,6-dialkylfulvenes in reaction with α-naphthyllithium is studied. It is found for the first time that organolithium causes fulvenes to undergo reductive coupling reaction. In ether-THF, α-naphthyllithium also adds on the exo-cyclic double bond on 6, 6-dimethyl-, diethyl-and 6-methyl-6-ethylfulvene and abstracts α-hydrogen from the side chain of the fulvene in competition with the reduction and reductive coupling reaction. The reductive coupling reaction takes place when α-naphthyllithium reacts with 6-methyl-6-n-propyl-, -n-butyl-, and -i-butylfulvenes. There are various ways of activating 6, 6-polymethylene-fulvenes including tetra-, penta-, and hexamethylenefulvenes, all related with their structures. In ether-petroleum ether (1: 1), except that the 6, 6-tetramethylene-fulvenes undergoes α-hydrogen abstraction reaction, all the other 6, 6-dialkylfulvenes, 6, 6-penta- and hexamethylenefulvenes with α-naphthyllithium mainly undergo addition reaction.From展开更多
2-硝基咪唑是一种重要的医药中间体,可用于合成多种抗癌药物,通过对其结构进行修饰,有望开发新型活性药物分子。以2-氨基嘧啶和3-溴丙酮酸乙酯为起始原料,经过缩合环化、肼解、氧化和取代合成了一系列1-烷基-2-硝基-1 H-咪唑-5-甲酸乙酯...2-硝基咪唑是一种重要的医药中间体,可用于合成多种抗癌药物,通过对其结构进行修饰,有望开发新型活性药物分子。以2-氨基嘧啶和3-溴丙酮酸乙酯为起始原料,经过缩合环化、肼解、氧化和取代合成了一系列1-烷基-2-硝基-1 H-咪唑-5-甲酸乙酯(7a~7d)及其同分异构体1-烷基-2-硝基-1 H-咪唑-4-甲酸乙酯(8a~8d),该方法克服了传统合成路线中氮原子上取代基仅为甲基的局限性。研究不同取代基对2种异构体比例的影响,结果表明:随着取代基团的给电子能力增强,更加有利于化合物7的生成。所有合成化合物的结构都经过1 H NMR,13 C NMR和MS(ESI)确证或表征。展开更多
By the reaction of different aromatic dicarboxylic acid with zinc nitrate, three metal-carboxylate frameworks, [Zn3（BDC）3（EtOH）2]（1）, [Zn3（BDC）3（py）2]·2DMF（2）, and [Zn3（NH2-BDC）3（H2O）2]·5DMF...By the reaction of different aromatic dicarboxylic acid with zinc nitrate, three metal-carboxylate frameworks, [Zn3（BDC）3（EtOH）2]（1）, [Zn3（BDC）3（py）2]·2DMF（2）, and [Zn3（NH2-BDC）3（H2O）2]·5DMF（3） which are constructed on the same linear trinuclear Zn3（RCOO）6 secondary building units, have been synthesized and characterized by X-ray diffraction analyses. Structural analyses showed that there are terephthalic acids as ligand linkers to form the hxl topological layer structures for 1 and 2. The introduction of the rigid aromatic ring pyridine in 2 as the terminal co-ligand of Zn3-SBU to instead of the flexible ethanol in 1, will form the layer-pillared supramolecular systems with 2-D crisscross channels, through its π-π stacking interactions. Owing to the steric hindrance of amino groups, 3 was assembled into a three-dimensional porous structure with pcu topology derived from the 2-amino-terephthalic acid as linkers to connect the Zn3-SBUs through a head-to-tail type.展开更多
文摘The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found that its retention rate of mechanical properties is far higher than that of the control sample. The results of thermogravimetric analysis show that its thermal-decomposing temperature rises largely. The analysis of oxidation mechanisms indicates that the main reasons for thermal oxidation resistance are that rare earth elements are of the utility to discontinue autoxidation chain reaction and that the formed complex structure has steric hindrance effect on oxidation.
基金financially supported by the National Natural Science Foundation of China (No.21504075)Natural Science Foundation of Hunan Province (No.2017JJ3294)
文摘Long-alkyl tail triphenylene （TP） side-chain liquid crystalline polymers （SCLCPs） with different spacer length （P-m-TP, m = 2, 3, 4, 6, 8, which is the number of carbon atom in the flexible alkyl spacers） have been successfully synthesized via free radical polymerization. The differential scanning calorimetry （DSC）, polarized light microscopy （POM）, ultraviolet-visible spectroscopy （UV- Vis）, wide-angle X-ray diffraction （WAXD） and small-angle X-ray scattering （SAXS） measurements were performed to investigate the influence of multiple effects on the self-organization behaviors of P-m-TP, including steric effect, decoupling effect and π-π stacking effect. The experimental results revealed that P-m-TP （m = 2, 3, 4） formed the columnar phase which was developed by the TP moieties and the main chain as a whole, suggesting that the side-chains had strong steric effect even though the number of spacer length （m） exceeded 4. In addition, the clearing points （Tis） of the polymers were above 300 ℃. When m = 6 and 8, the polymers displayed hexagonal columnar phase and exhibited the low Tis （91 and 80 ℃ respectively）, originating from the self-assembly of triphenylene due to the decoupling effect and π-π stacking effect. This work offers a viable and inspiring pathway to control the phase transition temperature and phase structure ofTP SCLCPs via simply tailoring the spacer length and increasing the alkyl tail length of TP.
基金Project supported by the National Natural Science Foundation of China.
文摘<正> The steric structure and solvent effect of 6,6-dialkylfulvenes in reaction with α-naphthyllithium is studied. It is found for the first time that organolithium causes fulvenes to undergo reductive coupling reaction. In ether-THF, α-naphthyllithium also adds on the exo-cyclic double bond on 6, 6-dimethyl-, diethyl-and 6-methyl-6-ethylfulvene and abstracts α-hydrogen from the side chain of the fulvene in competition with the reduction and reductive coupling reaction. The reductive coupling reaction takes place when α-naphthyllithium reacts with 6-methyl-6-n-propyl-, -n-butyl-, and -i-butylfulvenes. There are various ways of activating 6, 6-polymethylene-fulvenes including tetra-, penta-, and hexamethylenefulvenes, all related with their structures. In ether-petroleum ether (1: 1), except that the 6, 6-tetramethylene-fulvenes undergoes α-hydrogen abstraction reaction, all the other 6, 6-dialkylfulvenes, 6, 6-penta- and hexamethylenefulvenes with α-naphthyllithium mainly undergo addition reaction.From
文摘2-硝基咪唑是一种重要的医药中间体,可用于合成多种抗癌药物,通过对其结构进行修饰,有望开发新型活性药物分子。以2-氨基嘧啶和3-溴丙酮酸乙酯为起始原料,经过缩合环化、肼解、氧化和取代合成了一系列1-烷基-2-硝基-1 H-咪唑-5-甲酸乙酯(7a~7d)及其同分异构体1-烷基-2-硝基-1 H-咪唑-4-甲酸乙酯(8a~8d),该方法克服了传统合成路线中氮原子上取代基仅为甲基的局限性。研究不同取代基对2种异构体比例的影响,结果表明:随着取代基团的给电子能力增强,更加有利于化合物7的生成。所有合成化合物的结构都经过1 H NMR,13 C NMR和MS(ESI)确证或表征。
基金supported by the National Natural Science Foundation of China(No.11375082,11305086,11175080)Science Foundation of Hunan Province Department of Education(No.12A117)the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(Wang X.F.)
文摘By the reaction of different aromatic dicarboxylic acid with zinc nitrate, three metal-carboxylate frameworks, [Zn3（BDC）3（EtOH）2]（1）, [Zn3（BDC）3（py）2]·2DMF（2）, and [Zn3（NH2-BDC）3（H2O）2]·5DMF（3） which are constructed on the same linear trinuclear Zn3（RCOO）6 secondary building units, have been synthesized and characterized by X-ray diffraction analyses. Structural analyses showed that there are terephthalic acids as ligand linkers to form the hxl topological layer structures for 1 and 2. The introduction of the rigid aromatic ring pyridine in 2 as the terminal co-ligand of Zn3-SBU to instead of the flexible ethanol in 1, will form the layer-pillared supramolecular systems with 2-D crisscross channels, through its π-π stacking interactions. Owing to the steric hindrance of amino groups, 3 was assembled into a three-dimensional porous structure with pcu topology derived from the 2-amino-terephthalic acid as linkers to connect the Zn3-SBUs through a head-to-tail type.
