N-烷基壳聚糖衍生物的合成及其对阳离子的吸附性能

烷基衍生物;阳离子吸附性能;N-烷基壳聚糖衍生物的合成及其对阳离子的吸附性能     

pH对十二烷基二甲基氧化胺与DNA相互作用的影响

pH对十二烷基二甲基氧化胺与DNA相互作用的影响;DNA;十二烷基二甲基氧化胺;相互作用     

系列长链烷氧基苯甲醛的合成研究

以长链正烷基醇为原料与氢溴酸作用 ,合成了长链正烷基溴 6个 ;再与对或间羟基苯甲醛反应 ,合成了烷氧基苯甲醛 9个、间烷氧基苯甲醛 8个 .由于烷基链长的不同 ,其产率为 70 %～ 94% .考察了催化剂、烷基链长、羟基位置对长链烷氧基甲醛合成的影响 .解析了各种产物的红外光谱 .     

液晶中间体对-烷基苯甲酸的高效液相色谱测定

1　引　　言对 烷基苯甲酸在精细化工行业中有着广泛的用途 ,尤其作为液晶材料的中间体 ,对其分析测定的灵敏度和准确度显得尤为重要。气相色谱 (GC)测定有机酸时 ,常因沸点较高 ,不易汽化需要对其衍生化再进行测定。由于有机酸反应不易定量进行 ,而直接影响测定结果的准确性。高效液相色谱测定有机酸比GC法简便 ,在测定芳香族羧酸和多元酸更是如此。对烷基苯甲酸一端为烷基 ,一端为羧基 ,考虑其分子极性的特点 ,因而采用高效液相色谱 (HPLC)测定。对于同系物而言 ,由于化合物结构上的相似 ,其色谱保留值呈现出一定的规律性 ,可以依此…     

N-吡咯烷基-2-吡啶甲酰胺(NPPFA)对水溶液中苯酚的萃取行为

N-吡咯烷基-2-吡啶甲酰胺(NPPFA)对水溶液中苯酚的萃取行为;N-吡咯烷基吡啶甲酰胺(NPPFA);萃取;苯酚     

全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化催化研究

传统的Lewis酸催化剂在环境的压力下受到挑战,全氟烷基磺酸盐和全氟烷基磺酰亚胺盐作为均相、高效的Lewis酸催化剂在有机合成中受到人们的关注.为了简化分离操作,人们对全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化进行了研究,并已取得巨大进展.本文综述了全氟烷基磺酸盐和全氟烷基磺酰亚胺盐分别负载在有机载体、无机载体以及离子液体上的多相化催化最新研究进展,简要概括了其制备方法和催化活性,并对其催化应用前景进行了展望.     

胶束电动毛细管色谱快速测定化妆品中的防腐剂

重氮烷基脲和对羟基苯甲酸酯(甲酯、乙酯和丙酯)是目前化妆品中较常添加的防腐剂。卫生部《化妆品卫生规范》对上述4种防腐剂均限定了用量,其中重氮烷基脲的含量(质量分数,下同)应不大于0．5％,对羟基苯甲酸酯的含量应不大于0．4％。因此有必要建立一个快速、简便的同时测定这4种防腐剂的方法。     

异烷基膦酸单烷基酯萃取分离稀土的研究

研究了异烷基膦酸单烷基酯系列萃取剂色层分离稀土的性能。结果表明,以八碳异烷基膦酸-1-甲基庚基酯分离稀土的性能最佳,体系酸度均较目前使用的萃取剂低,用1.73 mol/L HNO_3可将Tm、Yb、Lu完全分离,用它制成的负载树脂分离稀土,其柱效高,动力学性能好。另外,对萃取反应机理作了一些探讨。     

烷基膦酸二烷基酯的固—液相转移催化合成及其阻燃性能

烷基膦酸二烷基酯的固－液相转移催化合成及其阻燃性能王筱梅＊杨平蔡庆华鲍猛（山东建筑材料工业学院应用化学系济南２５００２２）关键词烷基膦酸二烷基酯，合成，相转移催化，阻燃性１９９６－０８－１２收稿，１９９７－０３－０３修回烷基膦酸二烷基酯是一类具有实用...     

氟烷基化与氟烷氧基化的研究——25.甲酸/三乙胺引发氟烷基碘对烯烃的加成

氟烷基碘对烯烃的催化加成,是将氟烷基引入碳氢化合物的有效途径。通常利用光照和自由基引发来实现。最近我们发现许多金属     

Stereochemical effect revealed in self-assemblies based on archaeal lipid analogues bearing a central five-membered carbocycle: a SAXS study

The relative stereochemistry (cis or trans) of a 1,3-disubstituted cyclopentane unit in the middle of tetraether archaeal bipolar lipid analogues was found to have a dramatic influence on their supramolecular self-assembly properties. SAXS studies of two synthetic diastereomeric archaeal lipids bearing two lactosyl polar head groups at opposite ends revealed different lyotropic behaviors. The cis isomer led to L(c)-L(α)-Q(II) transitions whereas the trans isomer retained an L(α) phase from 20 to 100 °C. These main differences originate from the conformational equilibrium (pseudorotation) of 1,3-disubstituted cyclopentanes. Indeed, this pseudorotation exhibits quite similar orientations of the two substituents in a trans isomer whereas several orientations of the two alkyl chains are expected in a cis-1,3-dialkyl cyclopentane, thus authorizing more conformational flexibility in the lipid packing.     

Separation of homologues and isomers of linear alkylbenzenesulfonates by capillary electrophoresis with sodium dodecyl sulfate,carboxylic acids and bile salts

The ability of several anionic compounds, including carboxylic and dicarboxylic acids, sodium dodecyl sulfate (SDS), and sodium deoxycholate (SDC) and other bile salts, to separate the C(10)-C(13) homologues and the corresponding 20 positional isomers of linear alkylbenzenesulfonates (LAS) by capillary electrophoresis was studied. Up to 19 peaks and a shoulder were observed with a background electrolyte (BGE) containing 10 mM phosphate (pH 6.8), 30% acetonitrile and 40 mM SDS, and 18 peaks were obtained with a BGE containing 10 mM borate (pH 9), 40% ethanol and 40 mM palmitic acid (PA). Resolution increased with the alkyl chain length of the carboxylic acid. Dicarboxylic acids with a short alkyl chain, as azelaic acid, were useful to separate the homologues without distinguishing between the isomers. Up to 16 peaks and a shoulder were distinguished with SDC. Resolution decreased with the other bile salts. The 6-C(11)/5-C(11) isomer pair was better resolved with SDC than with SDS, and the 2-C(12) isomer was isolated using both PA and SDC, but not with SDS. Only the 7-C(13)/6-C(13) pair could not be resolved with any of the discriminating agents used.     

Novel benzoic acid congeners of bilirubin

Three regioisomeric bilirubins and biliverdins with propionic acids replaced by benzoic acids were synthesized from the corresponding xanthobilirubic acids by oxidative coupling. The rubins were found to exhibit widely varying polarity, spectroscopic properties, and stereochemistry. The isomer with ortho benzoic acids (1o) was much less polar than either the meta (1m) or para (1p) because 1o (but not 1m and 1p) can adopt a folded conformation with both carboxylic acids intramolecularly hydrogen bonded to the opposing dipyrrinones. The consequences of such conformational differentiation are found in the varying 1H NMR, UV-vis, and circular dichroism spectral properties.     

Effect of Steric Hindrance on the Resolution of the Enantiomers of Alkyl Isothiocyanate Derivatives of Amino Acids on a Teicoplanin CSP Using a Methanol-Based Mobile Phase

The effect of steric hindrance on the resolution of the enantiomers of alkyl (i.e. methyl, ethyl, propyl, butyl, and tert-butyl) isothiocyanate derivatives of amino acids on a teicoplanin chiral stationary phase (CSP), with a methanol-based mobile phase, has been studied. Resolution was found to depend on the size of the alkyl group attached to the isothiocyanate reagent and deteriorated as the size of the group increased from methyl to tert-butyl under the same chromatographic conditions. This indicates that interaction between the isothiocyanate group and the chiral selector is important in chiral recognition. Better-than-baseline resolution was achieved for many amino acids with a basic amino or an amide group, for example histidine, lysine, arginine, and asparagine, because of increased solubility in the mobile phase after chemical derivatization. Revised: 22 September and 7 October 2005     

基于纳米镍催化的松香加氢研究--树酯酸组成的研究

松香的主要成份是枞酸型树脂酸,其因共轭双键的存在而易被氧化,大大降低了其附加值。经氢化后的松香具有抗氧性好、脆性小、热稳定性高、颜色浅等特点,因而广泛应用于胶粘剂、合成橡胶、涂料、油黑、造纸、电子、食品等工业部门[1]。采用催化加氢的方法可使枞酸型树脂酸中的共轭双键消除[2]。以枞酸为代表的反应式为:松香催化加氢主要有熔融法[3]和溶剂法[4],所用催化剂主要是Pd和N i。熔融法制氢化松香,当反应温度低于200℃时,枞酸加氢速度较慢,反应不完全。温度升高,氢化松香中枞酸含量显著地减少,但温度高于250℃时,树脂酸脱羧严重,甚至…     

Influence of solvents on the conformational order of C18 alkyl modified silica gels

The influence of solvents on the conformational order of C(18) alkyl modified silica gels is studied by means of variable temperature FTIR spectroscopy. Symmetric and anti-symmetric CH(2) stretching modes were utilized for getting qualitative information about the changes in alkyl chain conformational order as a function of both protonated and perdeuterated solvents. It was found that interaction between the C(18) alkyl modified silica gels and the mobile phase results in pronounced changes of the alkyl chain conformational order. Furthermore, it was observed that some perdeuterated solvents exhibit isotope effects, which again is reflected by a different alkyl chain conformational order as compared to the corresponding stationary phases with protonated solvents.     

Surface adsorption of zwitterionic surfactants: n-alkyl phosphocholines characterised by surface tensiometry and neutron reflection

The surface adsorption of n-dodecyl phosphocholine (C12PC) has been characterised by a combined measurement of surface tension and neutron reflectivity. The critical micellar concentration (CMC) was found to be 0.91 mM at 25 degrees C in pure water. At the CMC, the limiting area per molecule (A(cmc)) was found to be 52+/-3 A2 and the surface tension (gamma(cmc)) to be ca. 40.0+/-0.5 mN/m. The parallel study of chain isomer n-hexadecyl phosphocholine (C16PC) showed a decrease of the CMC to 0.012 mM and a drop of gamma(cmc) to 38.1+/-0.5 mN/m. However, A(cmc) for C16PC was found to be 54+/-3 A2, showing that increase in alkyl chain length by four methylene groups has little effect on A(cmc). The almost constant A(cmc) suggested that the limiting area per molecule was determined by the bulky PC head group. It was further found that the surface tension and related key physical parameters did not vary much with temperature, salt addition, solution pH or any combination of these, thus showing that surface adsorption and solution aggregation from PC surfactants is largely similar to the zwitterionic betaine surfactants and is distinctly different from ionic and non-ionic surfactants. The thickness of the adsorbed monolayers measured from both dC12hPC and dC16hPC was found to be 20-22 A at the CMC from neutron reflectivity. Neither A(cmc) nor layer thickness varied with alkyl chain length, indicating that as the alkyl chain length became longer it was further tilted away from the surface normal direction and the layer packing density increased. It was also observed that the thickness of the layer varied little with surfactant concentration, indicating that the average conformational orientation of the alkyl chain remained unchanged against varying surface coverage.     

Hydrogenation of Borylated Arenes

A cis‐selective hydrogenation of abundant aryl boronic acids and their derivatives catalyzed by rhodium cyclic (alkyl)(amino)carbene (Rh–CAAC) is reported. The reaction tolerates a variety of boron‐protecting groups and provides direct access to a broad scope of saturated, borylated carbo‐ and heterocycles with various functional groups. The transformation is strategically important because the versatile saturated boronate products are difficult to prepare by other methods. The utility of the saturated cyclic building blocks was demonstrated by post‐functionalization of the boron group.     

Transition state for alkyl group hydrogenation on Pt(111)

Substituent effects have been used to probe the characteristics of the transition state to hydrogenation of alkyl groups on the Pt(111) surface. Eight different alkyl and fluoroalkyl groups have been formed on the Pt(111) surface by dissociative adsorption of their respective alkyl and fluoroalkyl iodides. Coadsorption of hydrogen and alkyl groups, followed by heating of the surface, results in hydrogenation of the alkyl groups to form alkanes, which then desorb into the gas phase. Temperature-programmed reaction spectroscopy was used to measure the barriers to hydrogenation, DeltaE(H)(double dagger), which are dependent on the size of the alkyl group (polarizability) and the degree of fluorination (field effect). This example is one of only two surface reactions for which the influence of the substituents on DeltaE(H)(double dagger) has been correlated with both the field and the polarizability substituent constants of the alkyl groups in the form of a linear free energy relationship. Increasing both the field and the polarizability constants of the alkyl groups increases the value of DeltaE(H)(double dagger). The substituent effects are quantified by a field reaction constant of rho(F) = 27 +/- 4 kJ/mol and a polarizability reaction constant of rho(alpha) = 19 +/- 3 kJ/mol. These suggest that the transition state for hydrogenation is slightly cationic with respect to the alkyl group on the Pt(111) surface, RC + H <--> {RC(delta+)...H}(double dagger).     

A STUDY ON THE DEGRADATION MECHANISM OF PHOTOCROSSLINKING PRODUCTS FORMED BY CYCLIZED POLYISOPRENE-DIAZIDE SYSTEM UNDER THE INFLUENCE OF ALKYL BENZENE SULFONIC ACIDS

The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects of alkyl chain length and the concentration of alkyl benzene sulfonic acids on the rate of degradation reaction were discussed. It was found that in the initial stage of degradation, the cyclicity ratio and the average fused ring number did not change considerably, but the percentage of uncyclized parts content varied significantly. The suitable mechanism was supposed.