HY分子筛上苯甲醚酰化反应及动力学研究

在微型固定床反应器中以HY分子筛为催化剂,研究了苯甲醚和乙酸酐的酰化反应,得出最佳工艺条件为:反应温度110℃,苯甲醚和乙酸酐的摩尔比为5:1,反应物空速11.3h-1,催化剂粒径0.059～0.042mm,产物最高收率可达83.7％.同时研究了苯甲醚乙酰化反应初始阶段的动力学,结果表明,此阶段为准一级反应,反应速率常...     

Electrosynthesis and structural characterization of a novel aryl ether trimer

The structure of a novel trimer formed by three p-tert-butyl anisole moieties via the controlled potential electrolysis of p-tert-butyl anisole was determined by X-ray diffraction method. By cyclic voltammetry, we report a multistep electron transfer, each followed by a chemical reaction, resulting in an ECECEC mechanism. Preparative scale oxidation of p-tert-butyl anisole in dry acetonitrile leads to its two first oligomers. The symmetrical dimer, 2,2′-dimethoxy-5,5′-di-tert-butylbiphenyl, shows that the favored coupling sites are those in the ortho position of the methoxy group. The title compound, namely the 1-methoxy-bis-2,3-(2′-methoxy-5′-tert-butylphenyl)-4-tert-butylbenzene crystallizes in triclinic space group P-1 with a = 10.571(3) Å, b = 11.739(1) Å, c = 12.733(2) Å, α = 74.64(1)°, β = 88.71(2)°, γ = 76.58(2)°, V = 1480.8(5) Å³, and Z = 2. The structural analysis reveals that two p-tert-butyl anisole moieties are linked in ortho position on a third p-tert-butyl anisole fragment.     

Mesoporous molecular sieves: alkylation of anisole using tert-butylalcohol

Mesoporous aluninosilicate Al-MCM-41 molecular sieves with Si/Al ratios 25, 50, 75 and 100 have been synthesized under hydrothermal condition and these materials were characterized by XRD, FTIR, BET and pyridine adsorption techniques. The catalytic performance was examined in the vapor phase tert-butylation of anisole with tert-butanol at the temperatures between 150 and 250 °C under atmospheric pressure. The results indicate that Al-MCM-41 (25) was found to be more active than its relatives. The major products are found to be 4-tert-butyl anisole (4-TBA), 2-tert-butyl anisole (2-TBA) and 2,4 di-tert-butyl-anisole (2,4-DTBA). Maximum conversion of anisole is observed at 175 °C and decreased thereafter with increasing temperature. The influence of molar feed ratio, influence of temperature, WHSV and time on stream on the selectivity of products was investigated and the results are discussed.     

磷钨酸镓催化合成对甲氧基苯乙酮

以磷钨酸镓(GaPW_(12)O_(40))和磷钨酸铟(InPW_(12)O_(40))为催化剂,苯甲醚和乙酸酐为原料,通过Friedel-Crafts酰基化反应合成了对甲氧基苯乙酮(p-MOAP)。采用FTIR和XRD等方法对催化剂进行了表征;考察了催化剂种类、反应条件等对催化性能的影响。表征结果显示,GaPw_(12)O_(40)和InPW_(12)O_(40)保持了Keggin型结构。实验结果表明,GaPw_(12)O_(40)催化剂的催化效果最好,InPW_(12)O_(40)催化剂次之;在GaPW_(12)O_(40)催化剂0.1 g、乙酸酐20 mmol、n(苯甲醚):n(乙酸酐)=5、反应温度90℃、反应时间30min的条件下,乙酸酐的转化率达到98.49%,p-MOAP的选择性达到94.91%且纯度较高。     

MCM-41负载磷钨酸催化剂的制备及其对乙酰化反应的催化性能

采用水热合成法制备了介孔分子筛 MCM-41,并利用浸渍方法将磷钨酸负载在 MCM-41分子筛上,经煅烧得到 PW/MCM-41催化剂;利用 X 射线衍射、傅里叶变换红外光谱、N_2吸附-脱附和 NH_3程序升温脱附等手段对催化剂进行了表征;考察了 PW/MCM-41催化剂对苯甲醚及1,4-二甲氧基苯的乙酰化反应的催化性能。表征结果显示,磷钨酸负载到 MCM-41分子筛上后,保持了 Keggin 结构,MCM-41分子筛保持了介孔结构。实验结果表明,PW/MCM-41催化剂的活性随磷钨酸负载量的增大而降低;磷钨酸质量分数为30%的 PW/MCM-41催化剂上反应底物的转化率最高,使用该催化剂0.8 g,以10 mL 二氯甲烷为溶剂,在苯甲醚用量0.01 mol、乙酸酐用量0.02 mol、反应温度140℃、反应时间4 h 的条件下,苯甲醚转化率可达77.0%,对甲氧基苯乙酮的选择性为96.5%。     

Flow injection analysis of BHA by NiHCF modified electrode

Flow injection method is described for the determination of the antioxidant tert-butylhydroxy anisole (BHA) based on its catalytic oxidation at a nickel hexacyanoferrate (NiHCF) surface modified graphite wax composite electrode fabricated using a new approach. The electrochemical characteristics of the modified electrode were studied using cyclic voltammetry. The voltammetric response of BHA at the modified electrode showed current densities remarkably higher than the bare graphite electrode and occurred at a reduced over voltage of 200 mV. Linear calibration graphs were obtained in the range of 1.2 × 10⁻⁶–1.07 × 10⁻³ M. A detection limit of 6 × 10⁻⁷ M was obtained with a correlation coefficient of 0.9983 based on S/N = 3. Reliable results were obtained by applying the proposed flow injection method to determine BHA spiked in dehydrated potato flakes. Results suggest that the developed method can be effectively employed for the determination of BHA from food samples.     

对溴苯甲醚合成的研究

以溴化钠为溴源,氧气为氧化剂进行的苯甲醚的催化氧化溴代反应。确定较佳的工艺条件为:苯甲醚∶溴化钠∶TEMPO(摩尔比)为1∶1.5∶0.003,冰醋酸与水的体积比例为10∶3。以20mmol的苯甲醚在较佳工艺条件下,反应5h,转化率及选择性都达到98.0%以上。     

Effect of antioxidant principles isolated from mango (Mangifera indica L) seed kernels on oxidative stability of buffalo ghee (butter‐fat)

A method was developed to extract and isolate the antioxidant principles, ie mainly phenolic and phospholipid classes, from mango (Mangifera indica L) seed kernels using organic solvents. The presence of at least six phenolic compounds and eight phospholipids in the isolates was confirmed by chromatographic techniques. A phenolic preparation and a phospholipid preparation were prepared separately by dissolving the isolated compounds from mango seed kernels in buffalo ghee. The phenolic preparation contained 9.6 mg% water‐extractable phenolics, 69.5 mg% total phenolics and 6.39 mg% phospholipids. The phospholipid preparation contained 155.8 mg% phospholipids, 0.11 mg% water‐extractable phenolics and 0.19 mg% total phenolics. The addition of these preparations to buffalo ghee at 5, 10 and 20% levels individually and in combination significantly increased the levels of phenolics and phospholipids respectively. Samples of buffalo ghee with added BHA contained levels of these compounds similar to that of a control sample without any other additives. The antioxidant indices calculated from the induction period of ghee samples stored at 80 ± 2 °C. in comparison with the control were, in order, 10.11 (20% phospholipid and phenolic preparation) > 8.88 (10% phospholipid and phenolic preparation) > 8.66 (20% phenolic preparation) > 6.44 (5% phospholipid and phenolic preparation) > 5.44 (10% phenolic preparation) > 4.88 (20% phospholipid preparation) > 3.00 (5% phenolic preparation) > 2.77 (10% phospholipid preparation) > 2.22 (5% phospholipid preparation) > 1.44 (0.02% BHA). This demonstrated that the phenolics and phospholipids isolated from mango seed kernel, when added jointly to buffalo ghee, helped in extending the shelf‐life of ghee. © 2000 Society of Chemical Industry     

对甲氧基苯乙酸的合成新工艺研究

研究对甲氧基苯乙酸新的合成方法,即苯甲醚在三氯化铝催化下与草酰氯单乙酯发生Friede1-Crafts酰化反应得到对甲氧基苯乙酮酸乙酯,后者不经纯化直接与水合肼发生Wolff-Kishner-Huang反应得到目标产物,总产率为55.4%,其结构经IR、1HNMR和MS证实.