稀土—4—（2—吡啶偶氮）间苯二酚螯合物的高效液相色谱分离和测定

本文讨论了反相离子对液相色谱法分离和检测稀土-4-(2-吡啶偶氮)间苯二酚螯合物的各种条件,在12 min内完成了9种稀土螫合物的分离,校正曲线的线性范围是(ppm):La(0.01～3.20),Ce(0.03～2.8),Pr(0.06～3.5),Nd(0.05～3.8),Sm(0.01～3.0),Eu(0.05～3.4),Tb(0.02～3.0),Ho(0.01～3.4),Er(0.06～4.0).变异系数小于1.2％.     

Composition and major odorous compounds of the essential oil of Bifora radians,an aldehyde-producing weed

The composition of the essential oil of Bifora radians, an aldehyde-producing weed, has been investigated by capillary gas chromatography, coupled gas chromatography – mass spectrometry, on-line catalytic hydrogenation and coupled gas chromatography – infrared spectrometry. The nineteen compounds identified included eighteen aldehydes: seven alkanals (C6, C9, C10, C11, C12, C13, and C14), ten alkenals, including five (E)-2-alkenals (C12, C13, C14, C15, and C16), and one (E,E)-2,4-alkadienal (C13). Typical Bifora odors were attributed to three major (E)-2-alkenals, C12, C13, and C14.     

Role of solvent in the compatibility of a vinylchloride–vinylacetate–maleic acid terpolymer and nitrocellulose blends

The compatibility of cast films of a vinylchloride–vinylacetate–maleic acid terpolymer (VMCH) and nitrocellulose (NC) blends is influenced by solvents. Transparent films of VMCH/NC blends are obtained when cast from solvents such as tetrahydrofuran or cyclohexanone, whereas hazy films are obtained when cast from solvents such as acetone or ethylacetate. Visible spectroscopy and phase morphology were used to analyse the compatibility–incompatibility of the blend. Differential scanning calorimetry (DSC) studies demonstrate that the transparent film is compatible, but the hazy film is incompatible. Fourier transform infra-red (FTIR) studies establish that a greater interaction is observed between the polymer pair in case of the compatible blend than in the case of the incompatible blend. A solvent dependency of blend compatibility is reflected in this study. The conformational state of the polymers in solution, which is responsible for the compatibility phenomena, may depend on the donor number and/or Taft-β value of the solvent. The greater the donor number and/or the Taft-β value, the higher may be the level of interaction between the solvent and the polymer molecules, which in turn may give a compatible blend after removal of the solvent.     

Evidence of a phase transition of RbHCO3 from high-resolution solid-state 13C and 87Rb NMR by comparison with KHCO3

A variable-temperature high-resolution 13C and 87Rb solid-state NMR study of powder rubidium hydrogencarbonate, RbHCO3, is presented for the first time. At ambient temperature, RbHCO3 is formed by centrosymmetric dimers linked by hydrogen bonds, but almost no information is available on this compound concerning proton disorder and the low-temperature phase. However, potassium hydrogencarbonate, KHCO3, which has an isomorphic structure for the high temperature phase, was well studied: it undergoes a non-ferroic, non-ferroelectric phase transition at Tc = 318 K between two monoclinic structures. The protons are disordered in an asymmetric double-well potential in the low-temperature phase, and the double-well potential becomes symmetric in the high-temperature phase. By comparison with recent solid-state NMR experimental results on KHCO3, we show that RbHCO3 undergoes a phase transition at Tc approximately 245 K, and give evidence that the proton dynamic disorder in both compounds is very similar.     

Chromatographic evaluation of perphenylcarbamoylated β-cyclodextrin bonded stationary phase for micro-high performance liquid chromatography and pressurized capillary electrochromatography

Application of mono (6^A-N-ethylenediamine-6^A-deoxy) perphenylcarbamoylated β-cyclodextrin (β-CD) bonded stationary phase (CSP) in micro-high performance liquid chromatography (micro-HPLC) and pressurized capillary electrochromatography (p-CEC) was firstly presented. A series of racemic α-amidophosphonates were resolved in reversed- and normal-phase modes on this CSP. The investigated chromatographic parameters include retention factor (k′), separation factor (α) and resolution (Rs) of solutes. In addition, the structural variation of the solutes and the experimental factors affecting chiral separations have been examined, including the percentage of alcohol modifier, the linear velocity (u) of the mobile phase, electrical field strength, etc. Baseline separation was achieved for most of the entities. Hydrophobic interaction, steric effect and π-π interaction contribute to the possible mechanism. Comparative results indicate that higher Rs value up to 3.1 was found in micro-HPLC, higher efficiency up to 29,970 in p-CEC.     

相转移催化氧化合成苯甲酸

苯甲酸一般由甲苯氧化而成 ,工业上采用液相空气氧化生产苯甲酸[1 ] 。ＫＭｎＯ4氧化甲苯制备苯甲酸的方法是在实验室中最常见的一种方法[2 ] ,该法的优点是反应条件温和 ,操作简便 ;其缺点是反应时间长 ,产率低 (低于 40 % ) [3] 。为了提高ＫＭｎＯ4氧化法的产率 ,本文采用十六烷基三丁基溴化磷 (ＨＤＴＢＰ)和苄基三乙基氯化铵(ＢＴＥＡ)作相转移催化剂氧化甲苯制备苯甲酸 ,具有时间短 ,收率高等优点。同时又考虑到ＨＤＴＢＰ的催化效果虽然好 ,但价格昂贵 ,因此本文采用价廉易得的苄基三乙基氯化铵 (ＢＴＥＡ)作相转移催化剂氧化甲苯制…     

Optimization of St John's Wort flavonoid separation by reversed phase liquid chromatography on a silica-based monolithic column

Summary An optimization procedure for the separation of flavonoids from St John's Wort by reversed-phase high-performance liquid chromatography on monolithic stationary phase is described. Three-component mobile phase systems are studied using experimental design methodology. The starting experimental domain is a triangle, each vertex of which is a pure component. From preliminary isocratic experiments, truncations in the domain are performed leading to a quadrilateral shape working domain with no symmetry. To cope with both separation and analysis time, desirability functions are used. Optimal conditions are finally given by binary systems and the four flavonoids are separated in less than seven minutes.     

Formation of sol-gel nanostructured mullite by additions of fluoride ion

Summary The subject of this study was to investigate the effect of fluoride ions addition on the temperature of sol gel mullite formation based on the hypotheses that the presence of fluoride ions can decrease the temperature of mullite formation (in respect to common 980°C, in sol-gel processing). Polymeric sols were prepared by mixing TEOS and aluminum nitrate nanohydrate and by adding fluoride ions (from 2 to 5 mass%). DTA, TG, XRD and SEM were used for characterisation of mullite gel and crystalline mullite. The experimental results confirmed that the addition of fluoride ions decrease the temperature of mullite formation up to 890°C for the fluorine concentration of 3.5 mass%. Experimental results showed that the temperature of mullite formation is not a simple function of the fluoride ion content. The mechanism of fluorine effect was discussed in terms of the gelling process, gel structure and the phase separation before the mullite formation.     

高效液相色谱氮杂冠醚键合固定相的合成及性能研究

我们曾用γ－氯丙基键合硅胶（ＣＰＳ），在氢化钠（ＮａＨ）作用下合成了３－（氮杂－１８－冠－６）丙基键合固定相（ＢＣＰ）［１］．该固定相对碱基、核苷酸、硝基苯酚等有较好的分离选择性，但由于ＮａＨ对硅胶基质腐蚀作用较大，导致ＢＣＰ柱效及渗透性较低．本文采...     

聚乙二醇蓄热调温性能及其在功能纺织品上的应用

对聚乙二醇(PEG)的自身交联及其与纤维素纤雏之间的交联反应进行了研究，探讨了交联前后PEG热活性的变化，并对PEG在焙烘交联时的受热稳定性以及分子量对热活性的影响进行了讨论。研究表明，PEG发生交联反应后，热性能参教产生偏移，热活性降低；热活性与分子量有直接关系；过高的焙烘温度将导致PEG氧化降解，热活性下降。在适宜的工艺条件下，纺织品经PEG后整理可获得热活性。