Papers by Keyword: ¹H NMR

Abstract: The characterization of microstructure and basic properties of domestic butyl rubber 1751 ( IIR 1751) was performed with different testing , such as 1H-NMR spectrum, gel permeation chromatography, dynamic mechanical analysis, thermal gravimetric analysis and differential scanning calorimeter. And the comparison with Butyl 268 and Butyl 301 was made. The results showed that IIR1751 had a narrower molecular mass distribution, lower number-average molecular mass and lower weight-average molecular mass. The unsaturation degree of IIR1751 was close to Butyl 268 and Butyl 301. Its thermal stability was higher than the other and its ash content and volatile matter content was lower. Its glass transition temperature was same to Butyl 268’s, which was slightly higher than the Butyl 301. Dispersion of carbon black in IIR1751 vulcanizates was poor, but IIR1751 vulcanizates had good processing property, had a longer scorch safety period and fast curing rate. Its fatigue performance was good and its mechanical properties can achieve a better balance.

Abstract: Abstract. Ammonia is known as one of odorants emitted from landfill sites and several techniques such as deodorant spray, adsorption/absorption processes and incineration have been used for its removal. Among the measures to solve the problem of odor, spraying of deodorants such as diluted essential oil will be promising. This study was carried out to investigate the characteristics and mechanism of ammonia removal by monoterpenes of essential oils. Chemical composition of the essential oil has been analyzed by GC-MS, an ammonia test tube was used to determine ammonia concentration and thus quantify the ammonia removal characteristics of monoterpenes and essential oils, and the interactional mechanism between ammonia and limonene was investigated with 1H NMR spectrometry. The results indicated that the efficiency of ammonia removal by limonene was improved by increasing the molar ratio of limonene to ammonia. Comparison of 1H NMR spectra before and after the interaction of limonene and ammonia showed that the chemical shifts of hydrogen atoms distant from the double bond had the largest changes, the shifts of these signals to lower magnetic field. The interaction interfered with the magnetic spin of the hydrogen atoms and reduced the peak splitting. When the molar ratios of the essential oil of pine needles, β-pinene, α-pinene and limonene to ammonia were 15, the removal rates of ammonia at 100C were 100, 86.0, 72.0 and 46.5%, respectively.

Abstract: A novel preparation of aluminum diethylphosphinate (AlPi) as a novel class of phosphorous based flame retardants was carried out with gas-liquid free-radical addition reaction under atmospheric pressure. The ethylene was bubbled into the reaction mixture with the addition of the initiator. With this novel method the gas-liquid contact surface and the initiator concentration in the gas-liquid interface were increased largely, and the yield of the final product was improved to at least 80%. The molecular structure of the samples was confirmed by FTIR, ¹H NMR and ³¹P NMR spectroscopic analysis. Thermal stability of the final products was investigated in detail by TG-DTA.

Abstract: Polymers imprinted with (S)-(-)-1,1’-bi (2-naphthol) and (R)-(+)-1,1’-bi (2-naphthol) have been prepared by non-covalent imprinting. A combinational procedure was used to optimize the functional monomer and crosslinker. A copolymer of 2-vinylpyridine and divinylbenzene resulted in the best chiral recognition. The ratio of template to functional monomer and solvent in the pre-polymerization mixture were also optimized. The imprinted polymers were used as stationary phases in high-performance liquid chromatography (HPLC). The molecularly imprinted polymers (MIPs) were more selective when prepared using a less polar solvent. Effective separations of the enantiomers of racemic (±)-1, 1’-Bi (2-naphthol) were achieved by use of acetonitrile as mobile phase; no cross-selectivity was observed. Interactions between functional monomers and template were investigated by 1H NMR spectroscopy. The results suggest that hydrogen-bonding between the functional monomer and the template and π-π stacking interaction between the cross-linker and the template may contribute to chiral recognition.

Abstract: Thiirane is usually synthesized by epoxy resin, and there are considerable content of epoxy mixed in thiirane because of the poor yields. In this article, a novel separation method was used to get pure episulfide compound and epoxy compound from thiirane/epoxy resin synthesized in our lab. Furthermore, the perfect 1H NMR spectra of pure episulfide compound and epoxide compound were obtained. The quantitative analysis of content of epoxy groups in thiirane/epoxy resin was performed by using FTIR and was testified by 1H NMR. It was found that the analytical results of the conversion of epoxy groups by the two methods above coincided with each other well.