The copolymerizations of methyl acrylate （MA） with different N- arylmethacrylamide （N-ArMA） were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by;H...The copolymerizations of methyl acrylate （MA） with different N- arylmethacrylamide （N-ArMA） were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by;H NMR method. The monomer reactivity ratios were calculated by the Fineman-Ross （F-R） method. The reactivity ratios and the activity of various N-ArMA with MA were investigated.展开更多
α-Hydroxy ketones are frequently involved in biologically important compounds and,therefore,the determination of the stereochemistry of these structural elements has attracted the attention in natural products chemis...α-Hydroxy ketones are frequently involved in biologically important compounds and,therefore,the determination of the stereochemistry of these structural elements has attracted the attention in natural products chemistry.In this paper a simpler Mosher′s method was developed from the modified Mosher′s method.It only need one configuration of MTPA to determine the absolute configurations of four α-hydroxy ketones with their（S）-and（R）-MTPA esters using（）1H NMR.The signals of protons on the same side with phenyl ring will be in the higher field than those of on the different side ones.Consequently according to the model the main configuration of compounds 1,2,3 and 4 were determined as S,R,R and S, respectively.展开更多
近年来,31P-NMR(nuclear magnetic resonance)已成为研究环境有机磷的有力武器,然而此方法在湿地学研究中的应用却很少,关于湿地沉积物样品制备方法的研究更缺乏。本研究通过改变提取剂组成、提取剂比例、离心条件、检测扫描时间等因素...近年来,31P-NMR(nuclear magnetic resonance)已成为研究环境有机磷的有力武器,然而此方法在湿地学研究中的应用却很少,关于湿地沉积物样品制备方法的研究更缺乏。本研究通过改变提取剂组成、提取剂比例、离心条件、检测扫描时间等因素设计实验,寻找最佳的湿地沉积物样品处理及检测方法,以期为31P-NMR技术在湿地沉积物样品有机磷研究中的应用提供科学依据。结果表明采用:1mol·L-1 HCl预提取,0.25mol·L-1 NaOH+0.05mol·L-1 EDTA主提取,沉积物与提取剂比例为1∶8的提取方法,可获得更好的提取效果。提取完成后,采用冷冻高速离心可更好地分离提取液、避免某些磷组分的水解。此外,NMR扫描分析时间设为14~16h(约扫描25 000次)可获得更完整的图谱。相较于传统的化学分析法,31P-NMR法的样品前处理相对简单、分析时破坏性小且组分分辨完全,该技术的运用,有望获得湿地磷循环,特别是对有机磷认知的新突破。展开更多
To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether ...To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether of polyethylene glycols as precursors of the system were synthesized by a two-step process. The presumed structure of the product was characterized, by ^(13)C, ~1H NMR and IR spectroscopy. It was found that a side-reaction occurred between the secondary hydroxyl group of PEG-chlorohydrin and epichlorohydrin in some degree, resulting in a by- product containing—CH_2Cl side group. By selecting a characteristic signal, which is undistorted by the increase in the length of CH_2 CH_2—O segment, a ~1H NMR approach of determining the equivalent epoxy weight (EEW) was proposed. The method is valid to specimens even though the EEW is as high as 2,000. The examination of the specimens by DSC showed that epoxidation greatly depressed the crystallinity of the PEG's, whereas the T_g was raised.展开更多
文摘The copolymerizations of methyl acrylate （MA） with different N- arylmethacrylamide （N-ArMA） were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by;H NMR method. The monomer reactivity ratios were calculated by the Fineman-Ross （F-R） method. The reactivity ratios and the activity of various N-ArMA with MA were investigated.
文摘α-Hydroxy ketones are frequently involved in biologically important compounds and,therefore,the determination of the stereochemistry of these structural elements has attracted the attention in natural products chemistry.In this paper a simpler Mosher′s method was developed from the modified Mosher′s method.It only need one configuration of MTPA to determine the absolute configurations of four α-hydroxy ketones with their（S）-and（R）-MTPA esters using（）1H NMR.The signals of protons on the same side with phenyl ring will be in the higher field than those of on the different side ones.Consequently according to the model the main configuration of compounds 1,2,3 and 4 were determined as S,R,R and S, respectively.
基金The project supported by National Natural Science Foundation of China.
文摘To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether of polyethylene glycols as precursors of the system were synthesized by a two-step process. The presumed structure of the product was characterized, by ^(13)C, ~1H NMR and IR spectroscopy. It was found that a side-reaction occurred between the secondary hydroxyl group of PEG-chlorohydrin and epichlorohydrin in some degree, resulting in a by- product containing—CH_2Cl side group. By selecting a characteristic signal, which is undistorted by the increase in the length of CH_2 CH_2—O segment, a ~1H NMR approach of determining the equivalent epoxy weight (EEW) was proposed. The method is valid to specimens even though the EEW is as high as 2,000. The examination of the specimens by DSC showed that epoxidation greatly depressed the crystallinity of the PEG's, whereas the T_g was raised.
