甲基硅羟基封端硅树脂的合成及固化性能

将甲基三氯硅烷和二甲基二氯硅烷分别与二苯基二羟基硅烷反应得到1,1,5,5-四氯-1,5-二甲基-3,3-二苯基三硅氧烷(A)和1,1,5,5-四甲基-1,5-二氯-3,3-二苯基三硅氧烷(B)。按一定比例将(A)和(B)水解缩合得到完全是甲基硅羟基封端树脂(Ⅰ)。将甲基三氯硅烷和甲基三乙酰氯基硅烷分别处理一般共水解法硅封端树脂可得到另外两种甲基硅羟基封端树脂(Ⅱ)和(Ⅲ),将树脂Ⅰ、Ⅱ、Ⅲ与一般共水解法得到的具有相同R/Si和Ph/R(R代表甲基和苯基)的树脂(Ⅳ、Ⅴ、Ⅵ)进行固化试验,结果表明,甲基-硅羟基封端树脂(Ⅰ—Ⅲ)的固化速度为共水解法制得的以苯基硅羟基封端树脂(Ⅳ—Ⅵ)固化速度的两倍以上。     

浸渍法制备C_(18)反相高效液相色谱固定相

提出了一种浸渍法制备C_(18)高效液相色谱固定相的方法。以十八烷二甲基氯硅烷(ODC)为键合试剂、六甲基二硅氮烷(HMDS)为封尾试剂,通过浸渍法制备得到C_(18)高效液相色谱固定相。采用红外光谱(FTIR)、元素分析(EA)和氮气吸附与解吸附(BET)对该合成材料进行了表征,并通过SRM870评价体系对其疏水选择性、金属离子以及硅羟基活性进行评价。与商品柱Kromasil C_(18)相比,浸渍法制备的C_(18)固定相具有较少的金属离子活性及较低的硅羟基残余量。通过重复性考察,说明浸渍法制备的C_(18)柱键合层稳定,对溶质的保留重现性良好。     

聚二甲基硅氧烷-聚苯乙烯复合微流控芯片室温不可逆封合法的研究

研究了一种基于紫外光/臭氧(UV/O₃)表面改性和硅烷化技术的聚二甲基硅氧烷(PDMS)与聚苯乙烯(PS)的不可逆封合的新方法. 首先, 用UV/O₃处理PS使其表面产生羟基、羧基等极性基团; 然后用3-氨丙基三乙氧基硅烷(APTES)对UV/O₃处理后的PS硅烷化, 使其表面形成氨丙基硅分子链; 再将硅烷化后的PS与拟封合的PDMS同时用UV/O₃处理, 使两者表面均产生硅羟基. 最后将处理后的PDMS与PS贴合, 通过硅羟基之间的缩合实现两者的不可逆封合. 以接触角、XPS和ATR-FT-IR对封合过程进行表征. 封合的PDMS-PS复合芯片可承受大于0.5 MPa的压强. 采用该方法制备了PDMS-PS复合微流控芯片用于HeLa细胞的培养. 实验表明, HeLa细胞在PDMS-PS复合芯片通道内的生长状况大大优于在全PS芯片、略好于在全PDMS芯片内的生长状况.     

克拉霉素的合成新方法

以醚化剂1-乙氧基环己烯和硅烷化试剂1,1,1,3,3,3-六甲基二硅氨烷为保护试剂, 采用醚化-硅烷化保护法制备了克拉霉素. 以红霉素A肟为原料计算, 经肟羟基醚化、2',4"-OH硅烷化、6-OH选择性甲基化、脱保护至克拉霉素, 四步反应总收率为49.5%.     

不同有机体系中3种烷基膦酸类化合物的硅烷化衍生方法研究

应用人工神经网络原理,考察了吡啶-甲苯、乙腈-甲苯和四氢呋喃(THF)3种体系中,温度、时间、衍生化试剂及其用量对甲基膦酸(MPA)硅烷化衍生效率的影响,确定主要影响因素为衍生化试剂及其用量;在此基础上建立了MPA、异丙基膦酸(IPA)和甲基膦酸频哪酯(PMPA)的三甲基硅(TMS)衍生法和特丁基二甲基硅(TBDMS)衍生法;在3种体系中,选用N,O-双(三甲基硅烷基)三氟乙酰胺(BSTFA)或N-甲基-N-叔丁基二甲基硅烷基三氟乙酰胺(MTBSTFA)作衍生化试剂,选用体积分数为10%的衍生化试剂.稳定性实验表明:3种化合物的TBDMS衍生产物均比其TMS衍生产物稳定.采用核磁共振氢去耦磷谱技术(31P{1H} -NMR)对TBDMS衍生法进行了评价,衍生接近完全.     

硅烷化对Ti/HMS分子筛催化性能的影响

分别用水热法和气相沉积法制备了Ti/HMS分子筛,采用三甲基氯硅烷(TMCS)和六甲基二硅氮烷(HMDSZ)对Ti/HMS样品进行了气相硅烷化,并用X射线衍射、N2吸附、红外光谱、29Si核磁共振和紫外-可见光谱对样品进行了表征.丙烯环氧化反应的测定结果表明,硅烷化可显著提高环氧化催化活性.水热法制备的Ti/HMS经HMDSZ硅烷化后的催化活性比经TMCS硅烷化后的稍高;气相沉积法制备的Ti/HMS经HMDSZ硅烷化后的催化活性远高于经TMCS硅烷化后的催化活性.这是由于TMCS不但能与分子筛表面的硅羟基反应,而且能破坏分子筛骨架中的Si-O-Ti甚至Si-O-Si键,形成新的羟基,导致样品的亲水性较强,同时还能对气相沉积法制备的Ti/HMS中的四配位骨架钛产生破坏作用.     

云母表面金纳米颗粒单层膜的制备

近年来 ,随着纳米科技的兴起 ,纳米尺度的金颗粒以其独特的光学和电学性质在许多领域表现出潜在的应用价值 ,引起人们浓厚的研究兴趣 .金纳米颗粒单层膜在表面增强拉曼基底及纳米刻蚀等方面有着广泛的应用 [1,2 ] .以往人们多用双官能团硅烷化试剂对硅氧化物基底 ,如玻璃和石英等进行表面修饰 ,获得氨基、巯基或氰基等修饰的表面 ,再利用金纳米颗粒与上述功能团之间的化学相互作用 ,来制备金纳米颗粒单层膜 [3,4 ] .Fig.1　 Crystal structure of muscovite mica云母为层状结构的硅铝酸钾 (晶体结构示于图 1 ) ,表层为 0 0 0 1晶面 ,K+ 离…     

昆虫信息素的结构鉴定和合成XXIV: (TR,8S)-(+)-和(7S,8R)-(-)-午毒蛾性信息素的合成及β-羟基硅烷的立体化学

从Sharpless不对称环氧化反应所得的光学活性环氧醛(e.e.96-97%)与三甲基硅锂试剂反应,得到β-羟基硅烷.它们经转化成乙酰氧基化合物后,再通过β-乙酰氧基硅烷的消除反应和均相催化氢化即得到两个标题化合物.对β-羟基硅烷的各非对映异构体的构型进行了测定.     

醇(酚)羟基的硅烷化保护与去保护研究进展

醇(酚)羟基的硅烷化保护是一类重要的有机合成手段,目的在于使羟基稳定化,消除或减轻其引起的副反应。保护基中硅原子连接的基团空间位阻越小,该保护基的反应活性越大,生成的相应硅醚的稳定性则越差,在弱酸或弱碱的条件下即可脱除;硅原子连接的基团越大,该保护基的反应活性则越小,硅醚化反应越难发生,需要借助催化剂才能进行。本文尽可能全面地论述了有机硅烷保护基的类型,如三甲基硅烷、三乙基硅烷、叔丁基二甲基硅烷、三异丙基硅烷、苯基取代硅烷和桥型硅烷等,并讨论了其在不同环境下的活性及稳定性。     

聚硅乙炔烷的合成与性能研究

70年代初苏联学者首次报道了聚硅乙炔烷的合成^[1],1973年有人用炔化钙和二甲基二氯硅烷在熔融盐中反应,结果得到四环体物(Me₂SiC≡C)₄^[2]。为了研究这类聚合物的性能,我们采用了新的合成路线合成可熔的聚硅乙炔烷。乙炔和格氏试剂发生交换反应,生成炔基双格氏试剂,它和有机二氯硅烷发生缩聚反应,生成聚硅乙炔烷。     

低分子量有机胺的离子色谱法研究

 首次应用ＣＳ１２分离柱对１０种低分子量有机胺的离子色谱法进行了研究。采用了有机改进剂（乙腈），优化了色谱条件，建立了Ｃ４以下的有机胺的分析新方法。方法简便、快速、灵敏，可同时测定碱金属和碱土金属离子，准确度和精密度均满足分析要求。     

Micellar and aqueous‐organic liquid chromatography using sub‐2 μm packings for fast separation of natural phenolic compounds

The objective of the present work was to investigate the chromatographic behavior of natural phenolic compounds in micellar and aqueous‐organic LC using a short column packed with 1.8 μm particles. Firstly, the effect of ACN and SDS on elution strength and selectivity was examined by isocratic submicellar (0–30% ACN/5% 1‐butanol/1–6 mM SDS) and micellar (0–30% ACN/5% 1‐butanol/40–60 mM SDS) systems. The varied concentrations of two modifiers in the mobile phases revealed different eluting power. Then, the application of organic modifier gradient was discussed in both submicellar and micellar LC using mobile phases of 4 mM SDS/5% 1‐butanol or 50 mM SDS/5% 1‐butanol containing ACN gradient from 0 to 30%, respectively. For micellar system, the separation was found to be better in gradient than isocratic elution. Additionally, the sensitivity of aqueous‐organic LC was examined. The mobile phase was a mixture of ACN and water employing gradient elution at a flow rate of 0.5 mL/min, with analysis time below 9 min. It was found that separation efficiency was significantly better compared with micellar LC. Besides, the aqueous‐organic LC has been applied to separation of various phenolic compounds in Yangwei granule or Radix Astragali samples.     

Quantitative LC Analysis of Cyclosporine A in Ocular Samples

An isocratic reversed-phase HPLC method with ultraviolet detection at 205 nm has been developed for analysis of cyclosporine A (CyA) in rabbit ocular samples. Neither internal standard nor extraction was needed for sample preparation. Acetonitrile (ACN; 1 mL) was added to 250 μL aqueous and vitreous samples to precipitate proteins. The supernatant was dried and the residue was reconstituted in mobile phase and injected for HPLC analysis. Chromatography was performed on an octadecyl silane-A (ODSA) C₁₈ (4.6 × 250 mm, 5 μm) column. The column temperature was fixed at 70 °C and the mobile phase was ACN 65%, methanol 20% and water 15% at a flow rate of 1.5 mL min^?1. The calibration curve for CyA in rabbit ocular samples was linear over the concentration range 0.2 and 10 μg mL^?1 with a correlation coefficient of 0.9992. Intra-day and inter-day precision were 4.61–7.83% and 5.27–10.70%, respectively. Intra-day and inter-day accuracy were 89.2–108% and 83.4–111%, respectively. The limits of detection (LOD) and quantification (LOQ) were 5.7 and 38 ng mL^?1, respectively. The method was successfully used for analysis of CyA in real aqueous and vitreous humor samples from New Zealand albino rabbits. The method is therefore suitable for analysis of CyA in ocular samples.     

Separation and HPLC analysis of 15 benzodiazepines in human plasma

Benzodiazepines (BZDs) are often prescribed to schizophrenic or depressed patients, as a part of polypharmacy regimens. An HPLC method has been developed for the simultaneous determination of 15 BZDs in human plasma. Separation was obtained by using a C8 RP column and a mobile phase composed of 65% aqueous phosphate buffer at pH 3.0 and 35% ACN. The UV detector was set at 220 nm and clomipramine was used as the internal standard. A careful pretreatment procedure of plasma samples was developed, using SPE with C1 cartridges, which gives high extraction yields (> 97%). The LOQs were always lower than 7.6 ng/mL and the LODs always lower than 2.6 ng/mL for all analytes. The method was successfully applied to plasma samples from depressed and schizophrenic patients undergoing polypharmacy with one or more BZDs. Precision data, as well as accuracy results, were satisfactory and no interference from other drugs was found. Hence, the method seems to be suitable for the therapeutic drug monitoring (TDM) of patients undergoing therapy with one or more BZDs.     

Optimization of hydrophilic interaction LC by univariate and multivariate methods and its combination with salting‐out liquid–liquid extraction for the determination of antihypertensive drugs in the environmental waters

Hydrophilic interaction LC for the separation of four antihypertensive drugs was optimized by both univariate and multivariate methods. The column efficiency, resolution, and separation time were used as the three assessment parameters. The best separation condition of 97% ACN with 3% aqueous buffer containing 50 mM ammonium acetate at a pH of 3.0 was obtained by the two optimization methods. The multivariate optimization, orthogonal array design herein, was demonstrated to be a little tedious, but afforded a much better understanding of underlying separation factors. The content of ACN in the mobile phase contributed most significantly to separation. Furthermore, sample diluent and injection volume were found to influence the chromatographic performance. To match the hydrophilic interaction LC mobile phase, a proper sample pretreatment method, salting‐out liquid–liquid extraction, in which ACN was the extractant, was chosen. Since reserpine was unstable under both acidic and alkaline conditions, it was not studied in this part. The optimal salting‐out liquid–liquid extraction parameters were as follows: 400 μL ACN was added to 1 mL sample solution containing 500 mg NH₄Cl at a pH of 14.0. The linearity ranged from 0.01 to 1.00 μg/mL with r² > 0.9937. The LODs were between 1.9 and 2.5 ng/mL. The developed method was applied to the environmental water sample with good performance.     

Pharmaceutical analysis by supercritical fluid chromatography: Optimization of the mobile phase composition on a 2-ethylpyridine column

The separation of neutral, acidic, and basic pharmaceuticals with diverse physicochemical properties by packed column supercritical fluid chromatography (pSFC) on a 2-ethylpyridine column (25 cmx4.6 mm id, 3 mum particles) is presented. The optimization strategy involved separations at 100% methanol (MeOH) and at 50% MeOH/50% ACN while keeping the peak symmetry additives formic acid (FA) and isopropylamine (IPA) at constant levels of 0.25% v/v. By plotting the adjusted retention times as a function of the MeOH/ACN ratio, an optimal modifier ratio composition of 65% MeOH/35% ACN was found. The total set of 26 neutral, acidic, and basic pharmaceuticals was analyzed and the optimal composition experimentally verified. This mobile phase composition is currently used in pharmaceutical method development and open-access generic screening environments.     

Fast chiral separation by ligand-exchange HPLC using a dynamically coated monolithic column

The preparation and application of dynamically coated ligand-exchange chromatography phases for enantioseparation is described. The phases were prepared by pumping a solution of N-decyl-L-4-hydroxyproline, N-hexadecyl-L-4-hydroxyproline, or N-2-hydroxydodecyl-L-4-hydroxyproline through a commercially available monolithic RP-18 column. These coatings are stable against desorption for months at ambient temperature when aqueous mobile phases are used. The columns were applied to the chiral separation of amino acids, glycyl dipeptides and diastereomeric dipeptides, and tripeptides. The chiral selector can be removed or changed easily by washing the column with ACN or methanol. Ultrafast separations in the range of seconds were achieved using high flow rates.     

Development and validation of a rapid reversed-phase HPLC method for the determination of insulin from nanoparticulate systems

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of insulin in nanoparticulate dosage forms. Its application for the development and characterization of insulin-loaded nanoparticulates composed of polyelectrolytes has also been carried out. A reversed-phase (RP) C18 column and gradient elution with a mobile phase composed of acetonitrile (ACN) and 0.1% aqueous trifluoroacetic acid (TFA) solution at a flow rate of 1 mL/min was used. Protein identification was made by UV detection at 214 nm. The gradient changed from 30:70 (ACN:TFA, v/v) to 40:60 (v/v) in 5 min followed by isocratic elution at 40:60 (v/v) for a further five minutes. The method was linear in the range of 1-100 microg/mL (R2 = 0.9996), specific with a good inter-day and intra-day precision based on relative standard deviation values (less than 3.80%). The recovery was between 98.86 and 100.88% and the detection and quantitation limits were 0.24 and 0.72 microg/mL, respectively. The method was further tested for the determination of the association efficiency of insulin to nanoparticulate carriers composed of alginate and chitosan, as well as its loading capacity for this protein. Encapsulant release under simulated gastrointestinal fluids was evaluated. The method can be used for development and characterization of insulin-loaded nanoparticles made from cross-linked chitosan-alginate.     

Polyacrylamide-based monolithic capillary column with coating of cellulose tris(3,5-dimethylphenyl-carbamate) for enantiomer separation in capillary electrochromatography

A hydrophilic chiral capillary monolithic column for enantiomer separation in CEC was prepared by coating cellulose tris(3,5-dimethylphenyl-carbamate) (CDMPC) on porous hydrophilic poly(acrylamide-co-N,N'-methylene-bisacrylamide) (poly(AA-co-MBA)) monolithic matrix with confine of a fused-silica capillary. The coating conditions were optimized to obtain a stable and reproducible chiral stationary phase for CEC. The effect of organic modifier of ACN in aqueous mobile phase for the enantiomer separation by CEC was investigated, and the significant influence of ACN on the enantioresolution and electrochromatographic retention was observed. Twelve pairs of enantiomers including acidic, neutral, and basic analytes were tested and nine pairs of them were baseline-enantioresolved with acidic and basic aqueous mobile phases. A good within-column repeatability in retention time (RSD = 2.4%) and resolution (RSD = 3.2%) was obtained by consecutive injections of a neutral compound, benzoin, on a prepared chiral monolithic column, while the between-column repeatability in retention time (RSD = 6.4%) and resolution (RSD = 9.6%) was observed by column-to-column examination. The prepared monolithic stationary phase showed good stability in either acidic or basic mobile phase.     

The adsorption mechanism of nortryptiline on C18-bonded Discovery

The adsorption isotherms of an ionizable compound, nortriptyline, were accurately measured by frontal analysis (FA) on a C(18)-Discovery column, first without buffer (in an aqueous solution of acetonitrile at 15%, v/v of ACN), then with a buffer (in 28%, v/v ACN solution). The buffers were aqueous solutions containing 20 mM of formic acid or a phosphate buffer at pH 2.70. The linear range of the isotherm could not be reached with the non-buffered mobile phase using a dynamic range larger than 40,000 (from 1.2 x 10(-3) g/L to 50 g/L). With a 20 mM buffer in the liquid phase, the isotherm is linear for concentrations of nortriptyline inferior to 10(-3) g/L (or 3 micromol/L). The adsorption energy distribution (AED) was calculated to determine the heterogeneity of the adsorption process. AED and FA were consistent and lead to a trimodal distribution. A tri-Moreau and a tri-Langmuir isotherm models accounted the best for the adsorption of nortriptyline without and with buffer, respectively. The nature of the buffer affects significantly the middle-energy sites while the properties of the lowest and highest of the three types of energy sites are almost unchanged. The desorption profiles of nortriptyline show some anomalies in relation with the formation of a complex multilayer adsorbed phase of acetonitrile whose excess isotherm was measured by the minor disturbance method. The C(18)-Discovery column has about the same total saturation capacity, around 200 g of nortriptyline per liter of adsorbent (or 116 mg/g), with or without buffer. About 98-99% of the available surface consists in low energy sites. The coexistence of these different types of sites on the surface solves the McCalley's enigma, that the column efficiency begins to drop rapidly when the analyte concentration reaches values that are almost one hundred times lower than those that could be predicted from the isotherm data acquired under the same experimental conditions. Due to the presence of some relatively rare high energy sites, the largest part of the saturation capacity is not practically useful.