Mo_2(OAc)_4试剂在邻二醇类结构绝对构型确定中的应用

环状及非环状邻二醇结构的绝对构型的确定是一个令人关注的研究领域.目前国外文献介绍了一种通过使用过渡金属试剂Mo2(OAc)4进行环状及非环状邻二醇结构绝对构型研究的方法,只需将该试剂与溶液中的被测化合物混合即可形成螯合物,无需制备和分离,且立刻可以进行圆二色谱测定,通过诱导产生的一定波长下的Cotton效应与被测化合物的手性中心的关系,可以方便地应用螺旋规则完成绝对构型的研究.将系统地介绍这一方法学,包括对方法学的研究思路、实验步骤、对影响因素的研究结果,以及一些应用的实例.     

振动圆二色谱: 一种确定手性分子绝对构型的新方法

手性分子绝对构型的确定是一个极其重要且长期存在的问题. 振动圆二色谱是在红外波长区域测定分子圆二色性的一种新方法, 极大地扩展了圆二色谱的应用范围. 振动圆二色谱法通过构象搜索、量子化学计算等手段准确预测手性分子的振动圆二色谱图, 进而与实测谱图进行比较确定其绝对构型. 该方法已经得到了越来越广泛的应用, 必将成为一种有效测定手性分子绝对构型的常规方法.     

二维NMR测定1,3-双烯膦酸酯的构型

本文报道用1H NMR二维J谱、二维同核相关谱及NOE技术测定了三个共轭双烯膦酸酯的双键构型,并求得各δ和J值。     

高效液相色谱圆二色检测技术在手性化合物分析中的应用

对近年来高效液相色谱圆二色检测技术在手性化合物分析中的应用进展进行综述,简单介绍了高效液相色谱圆二色检测器的原理和特点,着重介绍了非手性色谱条件下圆二色检测技术在手性化合物对映体纯度测定、复杂基质中手性化合物分析以及在手性化合物绝对构型测定中的应用,并讨论了它的应用前景。     

改良的Mosher法测定高烯丙醇的绝对构型

有机化合物绝对构型的测定在有机合成和药物合成方面都有着举足轻重的地位.Mosher法就是利用核磁共振波谱技术来确定复杂化合物绝对构型时所采用的一种巧妙方法.本研究即采用改良的Mosher法对无水鞘氨醇类天然产物pachastrissamine及其异构体全合成过程中的重要中间体高烯丙醇进行了绝对构型的测定.     

圆二色谱和诱导圆二色谱在卟啉及其配合物研究中的应用*

本文综述了圆二色谱(CD) 和诱导圆二色谱( ICD) 在手性卟啉绝对构型研究,功能分子与卟啉作用时的绝对构型和空间结构研究, 手性双卟啉、卟啉聚集体以及超分子组装研究等方面的进展和应用。     

土槿皮乙酸的绝对构型

报导了用圆二色散激子手性法测下土槿皮乙酸的绝对构型, 结果表明具有3s, 4s,10R及11R的绝对构型.     

预柱反应的毛细管气相色谱法分析汽油中的共轭二烯烃

汽油中的共轭二烯烃是一种不安定成分,准确、迅速测定其含量,对研究油品质量及炼油工艺都有重要的意义。测定共轭二烯烃的方法早有报道,多用马来酸酐与共轭二烯发生定量反应,未反应的马来酸酐水解成马来酸,再用碱中和马来酸的方法测     

关于茎点霉联烯酸丙的绝对构型

茎点霉联烯酸丙1是一具全新作用机制的天然抗菌化合物, 其绝对构型在全合成中是从关键中间体炔丙醇4的绝对构型来推定的. 由于后者本身依赖于经验规则, 进一步获取实验证据显得很有必要. 为此我们用Mosher酯法对炔丙醇4的绝对构型进行了测定. 结果表明原先推定的绝对构型是正确的.     

昆虫性信息素共轭二烯的合成进展

许多昆虫性信息素具有共轭二烯的结构,它们的双键位置和几何构型是决定其生物活性的重要因素。立体选择性和区域选择性地合成共轭二烯是有机合成中十分有意义的研究课题。文章综述了昆虫性信息素共轭二烯的合成进展。     

Headspace gas chromatography-flame ionization detector method for organic solvent residue analysis in dietary supplements

An analytical method has been developed for the identification and quantification of 20 organic solvent residues in dietary supplements. The method utilizes a headspace sampler interfaced with gas chromatography and flame ionization detection. With split injection (5:1) and a DB-624 column, most of the organic solvents are separated in 9 min. The method has been validated and was found to be relatively simple and fast, and it can be applied to most common organic solvent residues. With the mass detector, the method was able to identify organic solvents beyond the 20 standards tested.     

A new method for identifying the types of organic matter

A new method for dividing the types of organic matter according to V and Ni contents in soluble organic matter determined by NAA is introduced. The research site was an oil-gas field in northeastern China. The type of organic matter is an important parameter in evaluating an oil or a gas field. The conventional organic geochemistry methods will meet unsurmountable difficulties when the maturity of organic matter is high. The method described in this paper can solve the problem.     

Prediction of the molar volume at the normal boiling point

A group contribution method for the prediction of the molar volume at the normal boiling point has been developed. The method can be used for organic and inorganic compounds. It cannot be used for elements and diatomic molecules. Group contributions are shown for a wide variety of hydrocarbons, organic halogen compounds, organic oxygen compounds, organic nitrogen compounds, organic sulfur compounds, organic boron compounds, organic silicon compounds, miscellaneous organics, and many inorganic compounds.Contrary to the corresponding states methods for the prediction of molar volumes, knowledge of critical properties, acentric factors, and reference volumes is not needed.     

Development of minimized mixing molecular orbital method for designing organic ferromagnets

Predicting the high spin stability of organic radicals correctly for designing organic ferromagnets remains a significant challenge. We have developed a method with an index (L_min) for predicting the high spin stability of conjugated organic radicals at the restricted open‐shell Hartree–Fock level. Unitary transformations were performed for localizing the coefficients of nonbonding molecular orbitals, and subsequently the localized coefficients were used to calculate L_min that indicates the high spin stability of conjugated organic radicals. This method can be combined with the elongation method to treat huge high spin open‐shell systems. Thus, this method is useful for designing organic ferromagnets. © 2015 Wiley Periodicals, Inc.     

Determination of stable carbon isotopes of organic acids and carbonaceous aerosols in the atmosphere

A wet oxidation method for the compound-specific determination of stable carbon isotopes (delta(13)C) of organic acids in the gas and aerosol phase, as well as of water-soluble organic carbon (WSOC), is presented. Sampling of the organic acids was done using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to an ion chromatography (IC) system. The method allows for compound-specific stable carbon isotope analysis by collecting different fractions of organic acids at the end of the IC system using a fraction collector. delta(13)C analyses of organic acids were conducted by oxidizing the organic acids with sodium persulfate at a temperature of 100 degrees C and determining the delta(13)C value of the resulting carbon dioxide (CO(2)) with an isotope ratio mass spectrometer. In addition, analysis of delta(13)C of the WSOC was performed for particulate carbon collected on aerosol filters. The WSOC was extracted from the filters using ultrapure water (MQ water), and the dissolved organic carbon was oxidized to CO(2) using the oxidation method. The wet oxidation method has an accuracy of 0.5 per thousand with a precision of +/-0.4 per thousand and provides a quantitative result for organic carbon with a detection limit of 150 ng of carbon.     

Decomposition of organic matter with molten alkali: determination of arsenic and antimony in organic compounds

Decomposition of organic matter with molten alkali has been examined as a method of opening out organic matrices for elemental detection and/or determination. The fusion product is readily soluble. Arsenic and antimony in organic compounds can be determined iodimetrically after mineralization by this fusion method.     

测定饮用水中总有机碳新方法的研究

为了更准确地分析饮用水体中有机物的污染程度,采用燃烧氧化―非分散红外吸收法中直接法和差减法相结合的新方法测定饮用水中总有机碳(TOC),对单独使用直接法或差减法进行了优化。通过实验确定了该方法的检出限为0.12 mg/L,相对标准偏差为0.62%～1.97%,加标回收率为94%～102%,可用于测定饮用水中的总有机碳。     

有机酸分析的柱后缓冲电导法与紫外法、直接电导法的比较

柱后缓冲电导法采用柱后调节pH值,电导检测器检测的方法检测有机酸,它避免了经常使用的紫外法选择性差,直接电导法灵敏度低的缺点,是可以实现有机酸准确定量的一种新型分析方法.本文比较了这三种方法的分析结果.     

Rapid extraction of water soluble organic compounds from airborne particulate matter.

Water soluble organic compounds (WSOC) in airborne particulate matter (PM) have received considerable attention in recent years due to their abundance and their importance in atmospheric processes. The analysis of WSOC is necessary for quantifying the relative contribution of individual organic compounds to the total WSOC mass. In the present work, we evaluated the performance of a microwave-assisted extraction (MAE) method for the determination of WSOC in PM and compared the data with those of a conventional ultrasonic extraction (USE). The experimental results showed that the MAE method requires a shorter extraction time (5 min) compared to USE. The isolated water-soluble organic fraction of PM was subsequently analyzed using ion chromatography (IC) for low molecular weight organic acids. The rapid MAE method was used in conjunction with IC for the analysis of organic acids in PM samples, collected from different sources.     

A simple method for measuring excess adsorption isotherms of organic eluent components on reversed‐phase packing materials

A simple frontal analysis method has been developed for the reliable measurement of excess adsorption isotherms of an organic component on reversed‐phase adsorbents in a series of programmed concentration steps. In the present method, a peak, which is produced by refractive index change in column eluate, is detected at 589 nm; it represents the elution volume of the boundary. The method is applied to the measurement of the excess adsorption isotherms of organic eluent components from water on commercially available reversed‐phase stationary phases. The results are in good agreement with the previously reported isotherms. We also measure the excess adsorption isotherms of organic eluent components from solutions containing electrolytes. There are not any interference peaks on the elution traces. The method is thus reliably applicable to the evaluation of the excess adsorption of organic eluent components in practical systems.