Synthesis of Chlorinated and Non-chlorinated Polyols from Model Cross-Metathesis Modified Triacylglycerols

Three pure triacylglycerols (TAG) containing decenoic acid (D), and stearic acid (S), were hydroxylated into chlorinated and non-chlorinated polyols and studied in detail. D is a fatty moiety that can result from the cross metathesis of small olefins with common vegetable oils such as soybean oil. A fundamental understanding relating chemical composition and derived structure, particularly the number and position of the hydroxyl groups, to physical properties was established allowing us to add some perspective to the growing body of knowledge on industrially relevant polyol and polyurethane systems produced with metathesis-modified TAG (MTAG). The hydroxyl value, crystallization and melting behaviors, thermal degradation behavior of the polyols were directly related to their peculiar shortened and primary functionality inherited from the parent MTAG. The effect of regiochemistry on the physical properties of the polyols was investigated with the chromatography fractions of the trichlorinated polyol of propane-1,2,3-triyl tris(dec-9-enoate), giving an unhindered insight into the role of short and terminal functionality of MTAG polyols that will help select the optimal isomer composition for designer polyurethane materials.     

Isomers of dialkyl diketo-pyrrolo-pyrrole: Electron-deficient units for organic semiconductors

Diketo-pyrrolo-pyrrole (DPP) is an important electron-deficient unit, and the alkylation of DPP can gives rise to good solubility of organic and polymer semiconductors in solvent. In this paper, we report our observations on the isomers of dialkyl DPP. The alkylation of DPP can take place on both the nitrogen and oxygen atoms, leading to the formation of three isomers. The presence of the isomers is evidenced by the nuclear magnetic resonance (NMR) and mass spectra. The yields of the isomers are affected by the experimental conditions, including the reaction temperature, reaction time and solvent. The isomers have different electronic structures and optical properties as revealed by the UV–Vis absorption spectroscopy, fluorescent spectroscopy, cyclic voltammetry and theoretical simulation using Gaussian 03 program with B3LYP/6-31G(d). Small molecules based on the DPP isomers with dialkylation at different sites were synthesized and investigated as donor materials of organic solar cells (OSCs). The photovoltaic performances of OSCs are consistent with the electronic structures of the DPP isomers.     

降低甲苯一段硝化产物邻对比的研究

研究了利用立体位阻、溶剂效应、多孔载体等对有效降低甲苯一段硝化产物邻对位异构体比例的影响,文中给出了部分实验结果。     

Separation and structure analysis of trisaccharide isomers produced from lactose by Lactobacillus bulgaricus L3 β-galactosidase

Using lactose as the substrate, galacto-oligosaccharides containing β-d-galactose residues were synthesised with β-galactosidase from Lactobacillus bulgaricus L3. The reaction mixture was fermented by yeast cells to consume the monosaccharides and disaccharides, and then it was fully acetylated in the presence of acetic anhydride under I₂ catalysis. Column chromatography of the resulting products, using ethyl acetate: petroleum ether as the eluent, generated two isomers of trisaccharide derivatives (I and II) in gram scale for the first time. Their structure characteristics were investigated by ESI-MS and NMR spectra. They were identified as (2,3,4,6-tetra-O-acetyl-d-galactopyranosyl)-β-(1 → 6)-(2,3,4-tri-O-acetyl-d-galactopyranosyl)-β-(1 → 4)-1,2,3,6-tetra-O-acetyl-α-d-glucopyranose (I) and (2,3,4,6-tetra-O-acetyl-d-galactopyranosyl)-β-(1 → 3)-(2,4,6-tri-O-acetyl-d-galactopyranosyl)-β-(1 → 4)-1,2,3,6-tetra-O-acetyl-α-d-glucopyranose (II), respectively. ESI-MS analysis of both deacetylated products of the two trisaccharide derivatives I and II revealed molecular ion peaks of free trisaccharides, which were structurally identified as Gal-β-(1 → 6)-Gal-β-(1 → 4)-Glc and Gal-β-(1 → 3)-Gal-β-(1 → 4)-Glc, respectively.     

气质联用仪的微分流技术测定混合芳烃中的三甲苯含量

针对进口混合芳烃中的"X"类有毒物质,建立混合芳烃中三甲苯含量的气质联用(GC-MS)测定方法。运用气相色谱质谱的微分流技术,对混合芳烃中的3种三甲苯的同分异构体进行定性和定量分析,该方法准确度高,回收率99.06~101.8%,最大标准偏差0.04%。     

Isomer Identification of Monohydroxylated Polycyclic Aromatic Hydrocarbon Metabolites by Gas Chromatography/Fourier Transform Infrared Spectroscopy and Carbon-13 Nuclear Magnetic Resonance Spectroscopy

The foundation for a systematic approach utilizing spectral/structural correlations was established for unambiguous identification of monohydroxylated polyaromatic hydrocarbon metabolite (PAHm) isomers. Using elements of a theoretical/empirical valence-bond model developed earlier in our laboratory for isomer identification of chlorinated dibenzo- p -dioxin isomers, both gas chromatography/Fourier transform infrared spectroscopy (GC/FTIR) and carbon-13 nuclear magnetic resonance ( 13 C NMR) spectroscopy were employed for PAHm isomer identification. Results indicate that PAHm isomers also can be systematically identified by these techniques. However, many of the parameters leading to the success of the dioxin analysis (high symmetry of the parent dioxin molecule and laterally stabilized delocalization from chlorine substituents through ether linkage oxonium ions) are not generally present in the PAHm ring systems under investigation. The observed infrared parameters in PAH metabolites are C--O stretch, O--H stretching and bending vibrations, along with C=C skeletal stretching vibrations. In addition, 13 C NMR parameters such as chemical shift perturbations for carbons adjacent to functional groups have been observed.     

Constant-Isomer Benzenoid Series and a Topological Paradigm

The separate sets of constant-isomer benzenoid monoradicals, diradicals, triradicals, tetraradicals, etc. have the same sequence of isomer number counts. Those monoradicals, diradicals, triradicals, tetraradicals, etc. with the same isomer numbers also have a one-to-one topological matching among the member benzenoids.     

盐酸去氧肾上腺素光学异构体测定方法研究

目的：建立高效液相色谱法测定盐酸去氧肾上腺素的光学异构体。方法：采chiracel0D—H色谱（250mm×4．6mm,5μm）,流动相为正己烷-异丙醇-二C胺（85：15：0．1）,检测波长254nm。结果：盐酸去氧肾上腺素的线性范围为0．134-536μg·mL-1,检测限为0．07ug／ml,精密度RSD为1．0％。结论：该方法简便,灵敏,快速,准确,专属性强,可用于盐酸去氧肾上腺素的质量控制。     

用液相色谱法测定甲苯二异氰酸酯异构体含量

建立了测定工业苯二异氰酸酯中２,４－和２,６－体异构比的液相色谱法。先将甲苯二异氰酸酯用无水乙醇衍生成相应的甲苯二氨基甲酸乙酯,再采用自己合成的标准物质,使用Ｃ１８柱的５５／４５的甲醇／水移动相,用液相色谱法分析异构比。与美国ＡＳＴＭ规定的红外光谱法相比,本法准确,快速简易。