改性硅胶上的环氧乙烷水合反应

 先后采用氨丙基三乙氧基硅烷、甲醛-甲酸溶液和溴乙烷对大孔硅胶进行硅烷化、叔胺化和季铵化,制得改性硅胶,并考察了其对环氧乙烷水合制乙二醇的催化性能和催化剂的膨胀情况. 结果表明,在n(EO)/n(H2O)=1/22,95 ℃和1.0 MPa的条件下,环氧乙烷转化率为95.8%,乙二醇选择性为97.5%. 反应216 h后,催化剂几乎没有发生膨胀.     

硅胶管采样—液相色谱法测定空气中的氯氰菊酯

本文报道空气中氯氰菊酯的高效液相色谱测定方法，空气样品用硅胶管采样，经甲醇洗脱后用ＨｙｐｏｒｓｉｌＯＤＳ柱分离，紫外检测器检测，在本法的测定条件下，最低检测浓度为０．０４ｍｇ／ｍ＾３，当氯氰菊酯浓度范围为０～２５．０ｍｇ／Ｌ时，呈线性响应关系，相对标准偏差为２．４％～８．４％，本法的解吸效率为９６．８％～１００．３％，采样效率为１００％，氯氰菊酯在硅胶管中可稳定７ｄ。     

用环形扩散管和滤纸联用采样技术采集空气中氨和铵盐

建立了环形扩散管和滤纸采样夹联用，分形态同时采集空气中所态氨和颗粒态铵盐的方法。在同一气流中，采用涂渍１．５％草酸乙醇水溶液的环形扩散管采集气态氨，用浸渍上述试剂的玻璃纤维纸和慢速定量滤纸分别采集颗粒安和第一层滤纸上的铵盐挥发产生的氨气。用靛酚蓝比色法分别测定氨和铵盐。当采气流速为１．０Ｌ／ｍｉｎ时，采样效率高于９８．２％。将本法测得的氨气和铵盐的总量与标准采样方法的测定结果比较。无显著性差异（Ｐ     

气相色谱-质谱法测定化妆品中8种乙二醇醚类物质

建立了化妆品中8种乙二醇醚类物质的气相色谱-质谱分析方法。样品经甲醇超声提取,提取液经0.45μm微孔滤膜过滤后,采用气相色谱-质谱法分析,外标法定量。在优化的色谱条件下,8种乙二醇醚类物质可实现基线分离,在各自线性范围内线性良好(r20.999)。在0.05、0.5、5 mg/kg 3个加标水平下,平均加标回收率为82.2%~113.0%,相对标准偏差(RSD,n=6)为0.60%~8.5%。方法的检出限为0.10~1.00 mg/kg,定量下限为0.25~2.00 mg/kg。该方法操作简便,准确可靠,重现性好,可用于化妆品中乙二醇醚类物质的测定。     

气相色谱法测定创可贴中环氧乙烷和氯乙醇

将创可贴置于顶空瓶中,在已恒温60℃的烘箱中放置30 min,抽取瓶中气体进样检测环氧乙烷,并通过外标法定量。将创可贴置于密封瓶中,加5 mL浸提液,25℃下浸提24 h后进样检测氯乙醇,并通过外标法定量。气相色谱法检测环氧乙烷的加标回收率为93.1%～97.5%,检出限(3S/D)为0.1μg/g。气相色谱法检测氯乙醇的加标回收率为93.2%～99.3%,检出限(3S/D)为0.05 mg/L。     

溶胶凝胶法制备的Cu/SiO2催化剂及其催化草酸二甲酯加氢反应

采用溶胶凝胶法制备了用于草酸二甲酯加氢合成乙二醇的Cu/SiO2催化剂,在优化的反应条件下,当催化剂中Cu含量为15%～25%时,草酸二甲酯转化率和乙二醇选择性分别达到99.9%和95.0%.通过N2吸附-脱附、透射电镜、X射线衍射、氢气程序升温还原、N2O滴定法和X射线光电子能谱等手段对各Cu/SiO2催化剂进行了表...     

乙二醇二缩水甘油醚的合成及作为阳离子型紫外光固化稀释剂性能研究

以三氟化硼乙醚络合物为催化剂,以氢氧化钠为成环反应的闭环剂,利用乙二醇和环氧氯丙烷为原料合成了乙二醇二缩水甘油醚.研究了催化剂三氟化硼乙醚络合物用量、环氧氯丙烷和乙二醇摩尔比、氢氧化钠和乙二醇摩尔比,以及成环反应温度这些因素对合成反应的影响.结果表明较好的合成反应条件是:三氟化硼乙醚络合物质量分数为0.40%,环氧氯丙烷和乙二醇较佳摩尔比为2.4:1,氢氧化钠和乙二醇较佳摩尔比为2.2:1,较佳的成环反应温度为30℃.同时,把乙二醇二缩水甘油醚作为稀释剂加入到环氧树脂E-51中,利用三芳基锍鎓六氟锑酸盐作为引发剂,制备了阳离子型紫外光固化涂料,其紫外光固化膜的拉伸强度为46.25MPa,杨氏模量为1487.26MPa,断裂伸长率为6.27%.     

草酸二乙酯催化加氢制乙二醇液相产物分析

介绍了一种草酸二乙酯催化加氢制乙二醇液相产物的气相色谱分析法,色谱分析在ＧＣ－１０３型色谱仪上进行,用ＣＤＭＣ－１ＣＸ型色谱数据处理机计算,液相产物在内填５％ＦＦＡＰ／６０～８０目硅藻土８８０（ＡＷＤＭＣＳ）的不锈钢色谱柱上分离,用热导检测器检测,以２０ｍＬ／ｍｉｎ流速的氢气为载气,每个样品的分析时间约为１０ｍｉｎ。方法快速简便,数据较为精密准确。     

Cu/SiO2催化剂的制备、表征及其对草酸二乙酯加氢制乙二醇的催化性能

用沉淀沉积法和不同加料顺序制备了一系列草酸二乙酯气相加氢制乙二醇的Cu/SiO2催化剂,考察了反应温度、反应压力及氢气/草酸二乙酯摩尔比对催化性能的影响,以优化催化剂的制备方法和反应工艺条件.通过TPR,XRD,BET,HRTEM和SEM对催化剂进行了表征,揭示催化剂的稳定性、成型和活性位的分布.通过对实验数据的分析,确定了最佳的制备方法、铜负载量、还原温度和反应工艺条件,使草酸二乙酯的转化率和乙二醇的收率分别达到94.8%和76.0%.     

Synthesis of Pd-Cu Bimetallic Electrocatalyst for Ethylene Glycol and Glycerol Oxidations in Alkaline Media

PdCu/C (XC-72) electrocatalyst was synthesized by a chemical reduction method using ethylene glycol as reaction media, polyvinylpyrrolidone as surfactant and sodium borohydride as reducing agent. Vulcan carbon XC-72 was employed as support and added through the PdCu synthesis procedure; further, Pd commercial (Pd/C, 20% ETEK) was used for comparison purposes. Physicochemical characterization consisted in XRD, XRF, EDS and TEM analyses. TEM micrographs showed the presence of semi-spherical nanoparticles with a particle distribution around 6 nm. X-ray diffraction patterns showed the typical face-centered cubic structure of Pd materials for commercial Pd and revealed a low crystallinity for PdCu/C. The XRF analysis showed a mass metal composition of 81% Pd and 19% Cu. EDS analysis was made to single particles exhibiting an average elemental composition of 92% Pd and 8% Cu. The electrocatalytic activity of PdCu/C and Pd/C was evaluated by cyclic voltammetry experiments toward ethylene glycol and glycerol oxidations using three concentrations (0.1, 1 and 3 M) and 0.3 M KOH as electrolyte. These experiments exhibited the superior performance of PdCu compared with commercial Pd by means of current densities associated to the electro-oxidation reactions where values at least 3-fold higher than Pd/C were found.     

A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol

Liquid organic hydrogen carriers (LOHCs) are powerful systems for the efficient unloading and loading molecular hydrogen. Herein, a liquid-to-liquid organic hydrogen carrier system based on reversible dehydrogenative coupling of ethylene glycol (EG) with ethanol catalysed by ruthenium pincer complexes is reported. Noticeable advantages of the current LOHC system is that both reactants (hydrogen-rich components) and the produced esters (hydrogen-lean components) are liquids at room temperature, and the dehydrogenation process can be performed under solvent and base-free conditions. Moreover, the hydrogenation reaction proceeds under low hydrogen pressure (5 bar), and the LOHC system has a relatively high theoretical gravimetric hydrogen storage capacity (HSC>5.0 wt %), presenting an attractive hydrogen storage system.     

Ethylene Glycol as New Mobile Phase for Resolution of Two-Component Mixture of Cationic Surfactants on Alumina Surface

Aqueous ethylene glycol (ethane 1,2 diol) as a green mobile phase has been used for thin layer chromatographic (TLC) studies of cationic surfactants on alumina layers. Nineteen solvent systems were used to examine the mobility of the surfactants and to discover the best TLC system for the selective separation of dodecyl trimethylammonium bromide (DTAB) from multi-component mixture of other surfactants. Among the TLC systems studied, M₃ (ethylene glycol: water, 8:2) was best for achieving the selective separation of DTAB from multi-component mixture of other surfactants because in this mobile phase mobility of all surfactants except DTAB were insignificant. Effect of organic additives in aqueous ethylene glycol mobile phase on the mobility of surfactants was examined. The results obtained on laboratory made alumina TLC plates and commercially available precoated alumina HPTLC plates were compared. The lower limits of detection of DTAB, CPC, CTAB, HDTAC, and TTAB were 0.02, 0.05, 0.04, 0.06, or 0.08 µg per zone respectively. The resolution of mixture of cationic surfactants was also examined in the presence metal cations as an impurity in the analyzed sample.     

气相色谱法测定乙二醇精馏液中1,2-丁二醇和一缩二乙二醇含量

采用气相色谱法对乙二醇蒸馏液中微量杂质1,2-丁二醇(DB)和一缩二乙二醇(DEG)进行跟踪分析。色谱柱为DB-624石英毛细管柱(30m×0.25mm×1.4μm),分离在二阶程序升温条件下进行,分流比为80∶1,检测器为氢火焰离子化检测器(FID),外标法定量。峰面积与其浓度线性关系良好,DB和DEG的平均回收率分别为99.31%和99.51%,相对标准偏差分别为2.85%及2.68%。本方法简便、准确、重现性好。     

Iridium-Catalyzed Selective Cross-Coupling of Ethylene Glycol and Methanol to Lactic Acid

An atom-economic approach that has an unprecedented high selectivity for the synthesis of lactic acid (LA) based on a catalytic dehydrogenative cross-coupling by using inexpensive bulk ethylene glycol and methanol is described. This method relies on the synthesis and utilization of a novel iridium catalyst bearing three N-heterocyclic carbenes derived from 1,3-dimethylbenzimidazolium salts, and exhibits outstanding activity in the production of LA [turnover frequency (TOF) up to 3660 h⁻¹] owing to an elegant metal–ligand cooperation.     

Automatic Headspace Sampling for Determination of Ethylene Dibromide Residues in Cereals

Abstract

The possibility was investigated to apply a commercially available automatic head-space sampler in trace analysis of ethylene dibromide (EDB, 1,2-dibromoethane), in cereals.

Samples of rice and wheat flour were thermostatted in closed vials at 70[ddot]C for 30min. The top gas was then automatically introduced into a gas chromatograph equipped with an electron capture detector. Quantitation was performed using external standards (untreated samples spiked with solutions of EDB in N,N′-dimethylacetamide).

The relative standard deviation of the method was 3.4% for rice and 4.5% for wheat flour, at a residue level of 0.008 mg/kg. The detection limit was 0.001 mg/kg (the official EC residue tolerance is 0.01 mg/kg).

Preliminary experiments with other fumigants were carried out as well.

The headspace technique in question has the following advantages over other methods for determining EDB residues in cereals: 1. No sample pre-treatment like extraction, steam distillation, purge and trap etc.; 2. Automated sample handling; 3. “Clean” chromatograms.     

A New Method for the Measurement of Airborne Formaldehyde Using Derivatization with 3,5-Bis(Trifluoromethyl) Phenylhydrazine and Analysis by GC-ECD and GC-MS/SIM

Abstract

A new method was developed and described for the measurement of airborne formaldehyde using derivatization with 3,5-bis(trifluoromethyl)phenylhydrazine (TFMPH) coated onto silica solid phase extraction cartridges. Analysis by GC-ECD provides a detection limit of 74 ng formaldehyde per sample. A field study was conducted to compare the use of TFMPH to 2,4-dinitrophenylhydrazine (DNPH) and NIOSH method 3500 (chromotropic acid, CTA). Samples were collected from indoor and outdoor environments known or suspected to contain formaldehyde. Use of TFMPH with GC-ECD analysis correlates well with both methods (R²=0.93, slope=1.07 vs. DNPH; R²=0.99, slope=1.06 vs. CTA). Spiked samples were shown to be stable at least 7 days when stored at –20 °C. Analysis of samples by GC-MS with selected ion monitoring (GC-MS/SIM) also proved feasible. Laboratory and field results show the use of TFMPH to be viable for quantifying airborne formaldehyde in occupational and environmental samples.     

碱性介质中二(碲酸根)合铜(Ⅲ)酸根氧化乙二醇一乙醚的反应动力学及机理

在碱性介质中用分光光度法研究了二过碲酸合铜(Ⅲ)配离子(DTC)氧化乙二醇一乙醚(EGE)的反应动力学及机理。反应速率表明:反应对DTC为准一级,对EGE为分数级;在保持准一级条件([EGE]》[DTC])下,表观速率常数随着OH^-浓度的增加而增大,随着TeO₄^2-浓度的增加而减小;有负的盐效应。据此提出了包括配离子和EGE形成络合物的前期平衡的反应机理,由假设反应机理推出的速率方程能很好的解释全部实验现象,进一步求得速控步的速率常数和活化     

Pt-WO3/C电极表面活化对乙二醇和CO氧化的作用

用丙酮和四氢呋喃混合溶液对Pt—WO3/C电极进行表面活化处理后，乙二醇在Pt—WO3/C电极上的电催化氧化活性大幅度提高．发现无论在中性溶液中还是在酸性溶液中，表面活化处理后的Pt—WO3/C电极，乙二醇的起始氧化电位负移，氧化峰电流在酸性介质中增加到表面活化处理前的3．2倍：中性介质中增加到表面处理前的4．7倍，其主要原因是表面活化处理后，一方面增加了催化剂Pt的活性表面，另一方面也促进了电极表面吸附的CO的电氧化，减少了CO对电极表面的毒化作用．     

高分散的介孔碳载Pt纳米粒子的制备及其对乙二醇的电催化氧化性能

以二氧化硅溶胶为硬模板,嵌段聚合物F127为软模板,通过双模板法合成了高介孔比例、窄孔径分布的介孔碳(MC).进而经乙二醇还原法制备了高分散的MC载铂催化剂(Pt/MC).采用循环伏安、计时电流、线性扫描伏安和电化学阻抗谱法研究了硫酸溶液中乙二醇在Pt/MC催化剂电极上的电化学氧化行为.实验结果表明,Pt/MC催化剂对乙二醇的电催化氧化性能显著高于商业化炭黑XC72R载Pt(Pt/XC72R)催化剂.电化学阻抗谱分析进一步揭示,乙二醇在Pt/MC催化剂电极上的电氧化反应具有较低的电荷传递电阻.Pt/MC催化剂高的电催化活性可以归结于MC大的孔径和均一的介孔结构对电子传输和传质的促进作用.     

Polarity Behaviour and Specific Interactions of Imidazolium‐Based Ionic Liquids in Ethylene Glycol

The molecular interactions of the ionic liquids (ILs) 1‐butyl‐3‐methylimidazolium tetrafluoroborate [C₄mim][BF₄], 3‐methyl‐1‐octylimidazolium tetrafluoroborate [C₈mim][BF₄] and 1‐butyl‐3‐methylimidazolium octylsulfate [C₄mim][C₈OSO₃] are investigated in ethylene glycol (EG) over the whole mole fraction range using fluorescence (steady‐state and time‐resolved), Fourier transform infrared and nuclear magnetic resonance (NMR) spectroscopy. The cybotactic region surrounding the pyrene fluorescent probe exhibits peculiar characteristics for different ILs in the EG‐rich region. The extent of solute–solvent interactions is assessed by determining the deviations of experimentally observed vibronic band intensity ratios of peak 1 to peak 3 of pyrene fluorescence (I₁/I₃) from a composite I₁/I₃ value obtained using a preferential solvation model. A distinct vibrational frequency shift for various stretching modes of EG (O? H) or ILs (C? H of ring protons, B? F and S?O of anions) indicates specific interactional preferences of EG toward the IL protons/anion. Splitting of the O? H vibration band of EG at 3000–3700 cm^?1 into three separate bands, and analysis of the changes in location and area of these bands as a function of concentration enable precise determination of the effect of ILs on hydrogen bridges of EG. NMR chemical shifts and their deviations from ideality show multiple hydrogen‐bonding interactions of varying strengths between unlike molecules in the mixtures. A comparison of spectroscopic results with thermodynamic properties shows that the mixing microscopic behaviour of the investigated systems is completely different from the macroscopic behaviour, which is primarily governed by the difference in shape, size and nature of the molecules.