Enhanced thermal stability of poly(vinyl alcohol) in presence of melanin

A novel method was developed to enhance the thermal stability of PVA by using natural and synthetic melanins from oxidation of dopamine. Thermogravimetric (TG) curves indicated that the synthetic melanin changed the thermal degradation behaviors of PVA and largely improved the decomposed temperature by 80–110 °C in nitrogen when incorporation of synthetic melanin with low content (0.5–2 mass%). The thermal degradation kinetics suggested the activation energies of PVA/synthetic melanin blends were much higher than these of pure PVA. Isothermal TG curves conformed that the PVA/synthetic melanin blends exhibited more thermal stability than pure PVA. Moreover, the chemical structure changes of macromolecular after degradation were characterized by using fourier transform infrared and the results suggested that elimination reaction on the first degradation step did not took place for the PVA/synthetic melanin blends at 270 °C.     

合成甜味剂检测技术的研究进展

综述近十年来食品中合成甜味剂的检测技术。着重介绍光谱法、毛细管电泳法、流动注射分析法、高效液相色谱法以及液相色谱串联质谱法等。结合实际需求,比较不同方法的特点,并对合成甜味剂检测技术的发展进行了展望。     

气相色谱-质谱结合准确质量测定快速鉴定合成大麻素

采用气相色谱-质谱（GC-MS）结合准确质量测定方法,利用保留指数、特征碎片丰度以及高分辨准确质量数据信息,快速鉴定样品中的合成大麻素组分。建立了JWH-018、JWH-073等12种合成大麻素标准物质的分析信息数据库,检测限达到了2.5~30 ng/mL,并成功利用该方法对未知样品进行了检测,确认样品中含有“JWH-081和JWH-018”合成大麻素组分。结果表明方法可以满足合成大麻素快速鉴定的要求。     

Automatic screening method for the rapid and simple discrimination between synthetic and natural colorants in foods

A simple screening method was developed to discriminate between synthetic and natural colorants present in foods in order to reduce the use of expensive instruments such as a liquid chromatograph with diode array detection. A rapid flow system was proposed in which samples containing natural and synthetic colorants in an acetic acid medium were passed through a wool/cotton column, where only synthetic colorants were retained and were then eluted with dilute ammonia. Yellow, red and green-blue-brown additives can be monitored at 400, 530 and 610 nm, respectively, with a conventional spectrophotometer. Complete discrimination (no false positives) between natural and synthetic colorants can be obtained for molar concentrations of natural colorants (in the absence of synthetic ones) up to 2000 (yellow), 2000 (red) and 10 000 (brown) times that of the detection limit (DL) of synthetic additives. The reliability of the method was established at five concentrations (between 0.5 and 3 DL) of the synthetic colorants tartrazine (yellow), erythrosin B (red) and brilliant black BN (brown). For a cut-off concentration of 2 DL, the percentage of false negatives ranges from 8 to 12%. Finally, the method was applied to screening several fruit drinks and candies for the determination of synthetic colorants with a sampling frequency of 10 h⁻¹.     

Amphiphilic properties of poly(oxyalkylene)amine-intercalated smectite aluminosilicates

Layered aluminosilicates, including synthetic fluorine mica and natural montmorillonite (MMT), were intercalated with poly(oxypropylene)-polyamine quaternary salts with a 230-5000 molecular weight range. The X-ray basal spacing of these silicates had been expanded from 13.5 to 83.7 A for the synthetic mica and to 92.0 A for MMT. The relative silicate dimensions (300-1000 nm for synthetic mica and 80-100 nm for MMT) were ascertained by direct TEM observations in the case of the co-intercalated synthetic mica and MMT mixtures with Mw = 2000 quaternary ammonium salts. The tailored organic incorporation of synthetic mica and MMT clays could alter these hydrophilic clays, making them amphiphilic, and enable the lowering of toluene/water interfacial tension to 2.0 mN/m at the critical concentration of 0.1 wt %.     

有机化学进展(2011~2012)

本文综述了中国大陆地区有机化学研究人员2011至2012年两年内在合成方法学、有机合成化学、元素有机化学以及天然产物化学等领域获得的重要成果。文章中共引用参考文献355篇,其中110多篇手性金属配合物和有机小分子催化的不对称反应、金属催化的碳氢键活化等合成方法学论文和30余篇氟有机化学论文基本来源于德国《应用化学》(国际版)和《美国化学杂志》。本文汇集了中国有机化学家两年中合成的150多个具有生物活性和化学结构多样性的天然产物,其中不乏具有高度挑战性的复杂天然分子。在近两年中中国有机化学家从陆地和海洋的生物体内发现各种不同类型新天然产物90多个。     

Vibrational spectra of the hydrated carbonate minerals ikaite,monohydrocalcite, lansfordite and nesquehonite

The Raman (200-4000 cm(-1)) and infrared (600-4000 cm(-1)) spectra of four rare carbonate hydrate minerals are reported. These are naturally occurring and synthetic ikaite CaCO3.6H2O, and nesquehonite MgCO3.3H2O; natural monohydrocalcite CaCO3.H2O, and synthetic lansfordite MgCO3.5H2O. The spectra of synthetic ikaite partially substituted with 2H2O and also with 13C were measured, as were those of synthetic deuteriated nesquehonite. Spectra of ikaite and lansfordite, both of which decompose at room temperatures, were measured below 0 degrees C. Assignments of fundamental modes are proposed.     

Towards the development of synthetic routes using theoretical calculations: an application of in silico screening to 2,6-dimethylchroman-4-one

This study describes an attempt to develop a synthetic route using theoretical calculations, i.e., in silico synthesis route development. The KOSP program created four potential synthetic routes for generating 2,6-dimethylchroman-4-one. In silico screening of these four synthetic routes was then performed. In silico screening involves theoretical analysis of synthetic routes prior to actual experimental work. A synthetic route using the Mitsunobu reaction had already been reported by Hoddgets et al. Theoretical investigations were also conducted on two S(N)Ar reactions as well as a Michael reaction before they were examined experimentally. In silico screening using DFT calculations indicated that only the Michael reaction was likely to produce the target. Experimental work confirmed that the target was obtained in a yield of 76.4% using the Michael reaction. The other two routes, except for the Mitsunobu reaction, failed to generate the target. Our results demonstrate that theoretical calculations can be used to narrow down the number of experiments that need to be conducted when developing novel synthetic routes.     

Fucosyltransferases as synthetic tools: glycan array based substrate selection and core fucosylation of synthetic N-glycans

Two recombinant fucosyltransferases were employed as synthetic tools in the chemoenzymatic synthesis of core fucosylated N-glycan structures. Enzyme substrates were rapidly identified by incubating a microarray of synthetic N-glycans with the transferases and detecting the presence of core fucose with four lectins and one antibody. Selected substrates were then enzymatically fucosylated in solution on a preparative scale and characterized by NMR and MS. With this approach the chemoenzymatic synthesis of a series of α1,3-, α1,6-, and difucosylated structures was accomplished in very short time and with high yields, which otherwise would have required extensive additional synthetic effort and a complete redesign of existing synthetic routes. In addition, valuable information was gathered regarding the specificities of the lectins employed in this study.     

煤基费托合成油中微量总铁的测定

铁系催化剂的残留污染一直是煤间接液化技术生产费托合成油工艺生产和产品质量控制的重点关注问题之一。准确分析合成油中微量残留铁的含量已成为工艺开发过程中至关重要的手段。该文对不同检测方法进行了对比,以燃烧灰化样品等离子体发射光谱检测铁含量的方法对不同沸点的合成油样品进行了验证,并通过实验数据优化了检测方法中的关键步骤。经验证费托合成油样品前处理最优条件为称样量5 g,马弗炉于500℃灰化1 h。该法对铁含量测定的回收率大于95%,相对标准偏差(RSD)不大于5.7%,检出限及定量下限分别为0.15 mg/kg和0.50 mg/kg。     

Comparison of ultra high performance supercritical fluid chromatography,ultra high performance liquid chromatography,and gas chromatography for the separation of synthetic cathinones

A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite‐5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended.     

降压药阿雷地平及其相关杂质的合成与表征

建立了降压药阿雷地平新的合成路线, 并讨论了新合成方法的优化条件, 反应整体收率提高了20%; 结合阿雷地平的结构特点和合成工艺分析出6种杂质, 并提供了其制备方法和表征结果; 采用高效液相色谱(HPLC)法测定阿雷地平中的相关杂质, 为其质量标准的制定提供了实验依据.     

Mass spectrometry of maytansinoids—A study on the fragmentation mechanism and identification of synthetic analogs of maytansine

Natural maytansinoids and their synthetic intermediates ( 1—9 ) were studied by means of mass spectrometry upon electron impact condition. The fragmentation pathway and spectra-structural relationship of these compounds were proposed. Based on the fragmentation pattern, structures of the synthetic analogs were identified.     

Identification of novel synthetic organic compounds with supersonic gas chromatography-mass spectrometry

Several novel synthetic organic compounds were successfully analyzed with a unique type of GC-MS titled Supersonic GC-MS following a failure in their analysis with standard GC-MS. Supersonic GC-MS is based on interfacing GC and MS with a supersonic molecular beam (SMB) and on electron ionization of sample compounds as vibrationally cold molecules while in the SMB, or by cluster chemical ionization. The analyses of novel synthetic organic compounds significantly benefited from the extended range of compounds amenable to analyses with the Supersonic GC-MS. The Supersonic GC-MS enabled the analysis of thermally labile compounds that usually degrade in the GC injector, column and/or ion source. Due to the high carrier gas flow rate at the injector liner and column these compounds eluted without degradation at significantly lower elution temperatures and the use of fly-through EI ion source eliminated any sample degradation at the ion source. The cold EI feature of providing trustworthy enhanced molecular ion (M+), complemented by its optional further confirmation with cluster CI was highly valued by the synthetic organic chemists that were served by the Supersonic GC-MS. Furthermore, the provision of extended mass spectral structural, isomer and isotope information combined with short (a few minutes) GC-MS analysis times also proved beneficial for the analysis of unknown synthetic organic compounds. As a result, the synthetic organic chemists were provided with both qualitative and quantitative data on the composition of their synthetic mixture, and could better follow the path of their synthetic chemistry. Ten cases of such analyses are demonstrated in figures and discussed.     

RASA: a rapid retrosynthesis-based scoring method for the assessment of synthetic accessibility of drug-like molecules

In this account, a rapid retrosynthesis-based scoring method for the assessment of synthetic accessibility of drug-like molecules, called RASA (Retrosynthesis-based Assessment of Synthetic Accessibility) is devised. RASA first constructs a synthesis tree for the target molecule based on retrosynthetic analysis; in this process a series of strategies are suggested for limiting combinatorial explosion of the synthesis tree. A scoring function (RASA-score) for the assessment of synthetic accessibility is then proposed based on the optional effective synthetic routes, the complexity of reaction, and the difficulty of separation/purification associated with the most favorable synthetic route. The contributions of individual components are calibrated by linear regression analysis based on the synthetic accessibility estimates of a training set (100 compounds) given by a group of medicinal chemists (G1). Two external test sets (TS1 and TS2), whose synthetic accessibility estimates were given by the group G1 medicinal chemists and another group (G2) of medicinal chemists (from literature), respectively, were adopted for the evaluation of RASA. The correlation coefficient between the calculated RASA-score values and the estimated scores by medicinal chemists for TS1 is 0.807 and that for TS2 is 0.792, which demonstrate the validity and reliability of RASA. The validity and reliability as well as the high speed of RASA and its capability of suggesting synthetic routes enable it a useful tool in drug discovery.     

合成化合物动物体内抗肿瘤实验方法研究进展

进行了动物体内抗肿瘤活性研究的多为天然药物,但其来源有限;虽然用于抗肿瘤研究的合成化合物种类较多,但对于其在动物体内抗肿瘤研究又相对偏少,所以,合成化合物抗肿瘤体内研究已经成为研究热点之一。本文对合成化合物抗肿瘤作用机制、体内肿瘤模型建立方法和体内抑瘤实验研究等方面的研究进展进行了评述,并通过大量实验数据对合成化合物毒性评价方法、抑瘤基本观察指标测定、氧化损伤相关酶活力的测定方法、组织病理学评价方法等体内抑瘤实验的评价标准和方法进行了详细总结,提出了合成化合物在体内动物抗肿瘤实验研究方法中亟待解决的问题,为新型抗肿瘤合成化合物体内药学活性研究提供有益的参考。     

Phase diagrams of surfactant/water/synthetic perfume ternary systems

The phase diagrams of hexadecyl polyoxyethylene ether (C₁₆POE₁₀)/water/synthetic perfume, and sodium dodecyl sulfate (SDS)/water/synthetic perfume ternary systems were prepared. The synthetic perfumes used are, d-limonene, -hexylcinnamaldehyde, -ionone, benzyl acetate, linalool, and eugenol. In a series of C₁₆POE₁₀/water/synthetic perfume ternary systems, as the hydrophilicity of synthetic perfume increases, the regions of normal and inverse micellar solution phases were found to be extended, while that of the lamellar liquid crystal phase was reduced. Moreover, every region of normal micellar solutions, inverse micellar solutions, and lamellar liquid crystal phases in SDS/water/synthetic perfume ternary systems was found to be smaller than those in C₁₆POE₁₀/water/synthetic perfume systems.     

不同有机胺对合成杂原子Ga－Si－ZSM－5分子筛的影响

考察了几种有机胺作引导剂对以水玻璃为硅源、硝酸镓为镓源合成Ｇａ－Ｓｉ－ＺＳＭ－５分子筛的影响。结果表明，合成体系的最佳碱度与有机胺有关，不同有机胺的合成效果相差很大，以正丁胺作引导剂可获得高结晶度的分子筛产物。通过与合成Ａｌ－Ｓｉ－ＺＳＭ－５的比较和一些条件试验，探讨了有机胺的作用，并对分子筛的形成过程进行了合理的推测。     

合成多肽疫苗研究进展

综述了合成多肽疫苗的研究进展,系统地介绍了目前寻找抗原肽的各种方法以及各类可用作疫苗接种的合成多肽抗原的制备和应用.