异丙苯在Cu-HMS分子筛上的催化氧化

以含Cu的中孔分子筛(Cu-HMS)为催化剂,研究异丙苯的催化氧化。研究发现,Cu-HMS催化剂的加入使异丙苯氧化的诱导期显著缩短。在75℃下,以Cu-HMS为催化剂,O2为氧化剂的纯异丙苯氧化反应,苯乙酮为主要副产物,反应的选择性和转化率都很高。当催化剂用量为1 5×10-4mol/ml时,反应8h后,异丙苯转化率为32 7%,目的产物的累积浓度(质量分数)为37 7%,选择性为99%;反应12h后,异丙苯转化率为42 4%,目的产物的累积浓度为46 3%,选择性为95 6%。     

Effect of natural antioxidants in virgin olive oil on oxidative stability of refined,bleached, and deodorized olive oil

The factors influencing the oxidative stability of different commercial olive oils were evaluated. Comparisons were made of (i) the oxidative stability of commercial olive oils with that of a refined, bleached, and deodorized (RBD) olive oil, and (ii) the antioxidant activity of a mixture of phenolic compounds extracted from virgin olive oil with that of pure compounds andα-tocopherol added to RBD olive oil. The progress of oxidation at 60°C was followed by measuring both the formation (peroxide value, PV) and the decomposition (hexanal and volatiles) of hydroperoxides. The trends in antioxidant activity were different according to whether PV or hexanal were measured. Although the virgin olive oils contained higher levels of phenolic compounds than did the refined and RBD oils, their oxidative stability was significantly decreased by their high initial PV. Phenolic compounds extracted from virgin olive oils increased the oxidative stability of RBD olive oil. On the basis of PV, the phenol extract had the best antioxidant activity at 50 ppm, as gallic acid equivalents, but on the basis of hexanal formation, better antioxidant activity was observed at 100 and 200 ppm.α-Tocopherol behaved as a prooxidant at high concentrations (>250 ppm) on the basis of PV, but was more effective than the other antioxidants in inhibiting hexanal formation in RBD olive oil.o-Diphenols (caffeic acid) and, to a lesser extent, substitutedo-diphenols (ferulic and vanillic acids), showed better antioxidant activity than monophenols (p- ando-coumaric), based on both PV and hexanal formation. This study emphasizes the need to measure at least two oxidation parameters to better evaluate antioxidants and the oxidative stability of olive oils. The antioxidant effectiveness of phenolic compounds in virgin olive oils can be significantly diminished in oils if their initial PV are too high.     

氧化石墨烯在萘氧化中的作用研究

石墨烯在催化领域的应用越来越受到人们的重视。本文构建了萘—叔丁基过氧化氢（TBHP）—氧化石墨烯的催化氧化体系,研究氧化石墨烯在萘氧化过程中的作用。考察了氧化石墨烯种类、溶剂种类、氧化剂含量、石墨烯用量、反应温度、反应时间等因素对萘氧化反应的影响。实验结果表明氧化石墨烯的引入可以提高萘的转化率和1,4-萘醌收率; 当萘用量为100mg,氧化剂（TBHP）2.4mL,氧化石墨烯RGO（10wt%）20mg,反应溶剂为乙酸（1.2mL）,反应温度100℃,反应时间22h 时,得到了较优的反应结果。在此基础上,初步探讨了氧化石墨烯对萘氧化的作用机理。     

过氧叔丁醇氧化合成3-氧代-a-紫罗兰酮

开发了一种以过氧叔丁醇为氧化剂,乙酰丙酮钒为催化剂的合成3-氧代-a-紫罗兰酮的方法。主要探讨了氧化剂用量、催化剂用量、溶剂、温度对反应的影响。得出3-氧代-a-紫罗兰酮的有利合成条件是-a-紫罗兰酮1．92g（10mmol）·VO（acac）2 0·13g（0．5mmol）,过氧叔丁醇50mmol,在35℃下于10mL丙酮中反应6h,3-氧代-a-紫罗兰酮的产率达到58％,纯度高于98％。     

13%过氧乙酸溶液热稳定性分析

为了研究过氧乙酸的爆炸危险性,采用绝热加速量热仪对13%过氧乙酸溶液进行了热危险性测试。通过数据校正和分析,得到了绝热条件下13%过氧乙酸溶液的初始放热温度为45.25℃,最大压力为1.31MPa,最高温升速率温度为113.10℃。结果表明,过氧乙酸溶液的热分解温度很低,在安全生产和储运过程中有一定的爆炸危险性。针对过氧乙酸的热危险性,提出采取适当措施,例如加强冷却,采用合理的泄放方式,以避免事故的发生。     

5-（2-噻吩）-2-对-甲苯基噁唑的合成

以2-溴-1-（2-噻吩）-1-乙酮和对-甲基苯甲胺为原料,在复合催化剂碘与叔丁基过氧化氢的作用下,通过氧化环合反应合成了5-（2-噻吩）-2-对-甲苯基噁唑。产物结构经FTIR,NMR 和MS检测。结果显示：合成产物的最佳条件为：2-溴-1-（2-噻吩）-1-乙酮1 mmol、对-甲基苯甲胺1.3 mmol、碘0.2 mmol、质量分数55%的叔丁基过氧化氢1.2mmol、碳酸氢钠1.0 mmol,室温下反应12 h,产物收率为89.7 %。抑菌圈测定结果显示该产物对大肠杆菌具有强的抑菌能力。     

大豆脂肪氧合酶酶促合成亚油酸氢过氧化物

研究了水相体系中大豆脂肪氧合酶酶促合成亚油酸(LA)氢过氧化物的反应,最佳反应条件为底物质量浓度4 11g/L,pH=9,5℃,反应时间120min,亚油酸氢过氧化物产率80%。当m(LA)∶m(surfactant)=1∶1时,Tween系列、CTAB、AOT、AEO4、OAPCG、S8390均能加速反应,其中AEO4使反应时间缩短至30min,产率提高12%。一些盐可以明显地加快反应进程,其中柠檬酸钠使反应时间缩短至15min。外源Fe3+在反应体系中的浓度为0 5μmol/L或外源Fe2+为5nmol/L时反应速度显著提高,消除了滞后期。     

Assessment of the antioxidant capacity of a fermented grain food product,Antioxidant Biofactor (AOB), by using pyranine and pyrogallol red as a combined probe

The role of antioxidants contained in foods, beverages, and supplements against oxidative stress has received much attention. The capacity of antioxidants has been assessed by various methods. In this study, the antioxidant capacity of a complex mixture of fermented grains has been assessed by using two probes, pyranine and pyrogallol red (PGR). A supplement commercialised as Antioxidant Biofactor, AOB, was used as a substrate. The extracts from AOB obtained with water and dimethylsulphoxide (DMSO) inhibited the free radical-induced consumption of pyranine and PGR in a concentration-dependent manner. They also suppressed the free radical-induced oxidation of human plasma. It was estimated that 1 g of AOB contained, as Trolox equivalent, roughly 0.13 and 0.24 mmol (2.5 and 4.7 wt%) antioxidants, which could be extracted by water and DMSO, respectively. This study shows that the combination of the above two probes is useful for assessing the total content and activity of antioxidants contained in complex mixtures.     

Studies on the decomposition of α-primary hydroperoxide of secondary butyltoluene in alkaline medium

α-Primary hydroperoxides of s-butyltoluene (SBT) are preferentially decomposed when the hydroperoxide concentrate is treated with 2 M aqueous sodium hydroxide at 70°C. The decomposition is complete in 1 h. The rate of decomposition and the nature of products formed suggest the reaction to be first order with respect to the primary-hydroperoxide concentration in accord with the Kornblum-De La Mare mechanism. Salt formation of the hydroperoxide precedes the decomposition.