Oxone/CaCl_2/TEMPO体系在温和条件下对醇的氧化反应

Oxone/TEMPO/CaCl_2(TEMPO=2,2,6,6-Tetramethyl-1-piperidinyloxy)是一种稳定安全和易得的氧化催化体系,在室温条件下,可以氧化苄基或烷基醇生成醛或酮.苄基伯醇很容易被氧化成相应的醛,有较高的反应收率(90%～96%),仲醇氧化成相应的酮,收率在81%～85%之间,1,4-丁二醇环氧化生成γ-丁内酯得到了94%的收率.     

纳米氧化铜用于温和条件下的异丙苯氧化研究

采用水热合成方法制备了具有片状结构的纳米CuO催化剂.该催化剂在温和的条件下对以分子氧为氧化剂的异丙苯氧化反应表现出高效的催化活性.在85℃、常压、催化剂用量为0.02g/mL异丙苯的条件下,反应9h,异丙苯的转化率、选择性和收率分别为55.1%、94.1%和51.8%.研究发现,该纳米CuO催化剂可以循环使用.同时对该纳米CuO催化剂催化其它含有α-H的芳烃化合物甲苯和乙苯的氧化反应进行了研究.实验结果表明,该催化剂的活性顺序为异丙苯>乙苯>>甲苯.     

Alcohol‐Selective Oxidation in Water under Mild Conditions via a Novel Approach to Hybrid Composite Photocatalysts

The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent‐free conditions, and using O₂ or H₂O₂ as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4‐(4‐(4‐hydroxyphenylimino)cyclohexa‐2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide‐based composite was first extensively characterized and then employed in the catalytic oxidation of 4‐methoxybenzyl alcohol to 4‐methoxybenzaldehyde under UV irradiation in water at room temperature. The corresponding aldehyde was obtained with unprecedented high selectivity (up to 86 %). The method is general and opens the route to fabrication of photocatalytic composites based on titanium dioxide functionalized with shuttle organic molecules and metal nanoparticles for a variety of oxidative conversions.     

Oxone/CaCl2/TEMPO体系在温和条件下对醇的氧化反应

Oxone/TEMPO/CaCl₂ (TEMPO＝2,2,6,6-Tetramethyl-1-piperidinyloxy)是一种稳定安全和易得的氧化催化体系, 在室温条件下, 可以氧化苄基或烷基醇生成醛或酮. 苄基伯醇很容易被氧化成相应的醛, 有较高的反应收率(90%～96%), 仲醇氧化成相应的酮, 收率在81%～85%之间, 1,4-丁二醇环氧化生成γ-丁内酯得到了94%的收率.     

Photocatalytic Degradation of Styrene in Aqueous Solution: Central Composite Design Optimization

In this study, the response surface methodology was first applied to optimize the photocatalytic degradation of styrene in aqueous phase under UV/TiO₂ system. Twenty experiments were done by adjusting three parameters (styrene concentration, TiO₂ dose, and pH) at five levels. Optimal experimental conditions for arbitrary aqueous styrene concentration (115 mg L^?1) were found: initial pH 7 and TiO₂ loading 2 g L^?1 with photocatalytic degradation efficiency of 79.2%. Furthermore, the main degradation intermediate produced was identified by GC/MS. The total organic carbon results revealed that the photocatalysis process could be effectively mineralized. Kinetics of the photocatalytic reaction followed a pseudo-first-order model.     

温和条件下Nb—MCM—41光催化氧化甲烷的研究

以含水的Nb-MCM-41中孔分子筛为催化剂,在温和条件下光催化氧化甲烷的反应结果表明,硅基Nb-MCM-41的反应活性高于Nb2O5,且有一定量甲醇和微量的甲醛生成。     

Formulation Development of Mirtazapine Liquisolid Compacts: Optimization Using Central Composite Design

Mirtazapine is a tetracyclic anti-depressant with poor water solubility. The aim of this study was to improve the dissolution rate of mirtazapine by delivering the drug as a liquisolid compact. Central composite design (CCD) was employed for the preparation of mirtazapine liquisolid compacts. In this, the impacts of two independent factors, i.e., excipient ratio (carrier:coating) and different drug concentration on the response of liquisolid system were optimized. Liquisolid compacts were prepared using propylene glycol as a solvent, microcrystalline cellulose as a carrier, and silicon dioxide (Aerosil) as the coating material. The crystallinity of the formulated drug and the interactions between the excipients were examined using X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), respectively. The dissolution study for the liquisolid compact was carried out as per FDA guidelines. The results showed loss of crystallinity of the mirtazapine in the formulation and was completely solubilized in non-volatile solvent and equally dispersed throughout the powder system. Moreover, drug dissolution was found to be higher in liquisolid compacts than the direct compressed conventional tablets (of mirtazapine). The liquisolid technique appears to be a promising approach for improving the dissolution of poorly soluble drugs like mirtazapine.     

A Statistical Approach for Optimization of Polyhydroxybutyrate Production by Bacillus sphaericus NCIM 5149 under Submerged Fermentation Using Central Composite Design

The aim of this work was to statistically optimize the cultural and nutritional parameters for the production of polyhydroxybutyrate (PHB) under submerged fermentation using jackfruit seed hydrolysate as the sole carbon source. On the basis of results obtained from “one variable at a time” experiment, inoculum age, jackfruit seed hydrolysate concentration, and pH were selected for response surface methodology studies. A central composite design (CCD) was employed to get the optimum level of these three factors to maximize the PHB production. The CCD results predicted that jackfruit seed hydrolysates containing 2.5% reducing sugar, inoculum age of 18 h, and initial medium pH 6 could enhance the production of PHB to reach 49% of the biomass (biomass 4.5 g/l and PHB concentration 2.2 g/l). Analysis of variance exhibited a high coefficient of determination (R ²) value of 0.910 and 0.928 for biomass and PHB concentration, respectively, and ensured that the quadratic model with the experimental data was a satisfactory one. This is the first report on PHB production by Bacillus sphaericus using statistical experimental design and RSM in submerged fermentation with jackfruit seed hydrolysate as the sole source of carbon.     

Co-N-Si/AC Catalyst for Aerobic Oxidation of Benzyl Alcohols to Esters under Mild Conditions

A stable, earth-abundant, reusable cobalt-based heterogeneous catalyst is developed for the oxidative esterification of alcohols under ambient conditions, featuring broad substrate scope, providing good to excellent product yields. This protocol enables easy recyclability of the catalyst, measured up to five times without significant loss of efficiency. The active sites of Co-N-Si/AC are proposed to be Co-N species.     

Transition-Metal-Free TEMPO Catalyzed Aerobic Oxidation of Alcohols to Carbonyls Using an Efficient Br2 Equivalent under Mild Conditions

An effective transition‐metal‐free catalytic system is developed for aerobic oxidations of alcohols. Using catalytic amount of bromide‐bromate coupling, H₂SO₄, and NaNO₂, together with 2,2,6,6‐tetramethylpiperidine N‐oxyl radical (TEMPO) in the presence of air, various alcohols could be converted into the corresponding aldehydes or ketones in good to excellent isolated yields under mild conditions.     

温和条件下甲醛在 Pt/TiO2 上催化氧化反应的原位漫反射红外光谱研究

 采用原位漫反射红外光谱研究了温和条件下 1%Pt/TiO2 催化剂上甲醛的吸附和氧化反应, 并对催化剂的失活进行了分析. 结果表明, Pt/TiO2 催化剂在室温条件下即可将甲醛氧化成 H2O 和 CO2, 100 oC 以下甲酸根的分解为决速步骤, 低温下催化剂失活是由于表面未能及时分解的甲酸根占据了催化剂的活性位, 升温至 100 oC 即可将甲酸根完全分解并恢复催化剂的活性.     

Evaluation and Optimization of Water-in-Oil Microemulsion Using Ternary Phase Diagram and Central Composite Design

In the present study, water-in-oil (w/o) microemulsions were prepared, evaluated, and optimized using pseudoternary phase diagram and central composite design (CCD). Ternary phase diagrams were designed to determine the microemulsion region whereas face-centered CCD helped in the determination of the effect of variables like oil type and surfactant ratio on globule size and viscosity of w/o microemulsion. The design exhibited that the factors have statistically significant effects (p < 0.0001) on the selected responses. The actual responses showed excellent agreement with the predicted values as suggested by the CCD with lower residual standard error. Similarly, the optimized values were found within the range as predicted by the model. Furthermore, other characteristics of microemulsions like pH, conductivity, refractive index, and transmittance were also analyzed. Overall, the primary objective of the research was to fabricate water-in-oil microemulsions which could facilitate effective delivery of hydrophilic molecules and drugs.     

不同水热条件下TiO2/电气石复合材料的光催化机制

为了解决TiO₂纳米光催化剂易团聚、禁带宽度大的缺点,本文采用水热法制备了TiO₂/电气石（3%）复合材料,研究了水热时间（2~10 h）和水热温度（120~200℃）对TiO₂/电气石（3%）的光催化性能的影响。发现光催化降解罗丹明B的降解率由单独TiO₂的60%提高到加入电气石后的99.4%。电气石具备自发极化电场效应,降低了TiO₂的禁带宽度和光生电子和空穴的复合率。在水热温度160℃、水热时间4 h条件下制备的TiO₂/电气石（3%）表现出最高的光催化降解罗丹明B的性能。说明TiO₂与这种有自发极化的材料复合能够有效提高其光催化性能。     

N-Bromo Reagent Mediated Oxidation of Urazoles to Their Corresponding Triazolinediones under Mild and Heterogeneous Conditions

Various N-bromo reagents [HMTAB, DABCO-bromine, DPTBE, and TBCA] were used as effective oxidizing agents for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones under mild and heterogeneous conditions at room temperature with good to excellent yields. Also the oxidation of some new 4-phenylurazole derivatives with these reagents is discussed.     

不同水热条件下TiO_2/电气石复合材料的光催化机制

为了解决TiO_2纳米光催化剂易团聚、禁带宽度大的缺点,本文采用水热法制备了TiO_2/电气石(3%)复合材料,研究了水热时间(2~10 h)和水热温度(120~200℃)对TiO_2/电气石(3%)的光催化性能的影响。发现光催化降解罗丹明B的降解率由单独TiO_2的60%提高到加入电气石后的99.4%。电气石具备自发极化电场效应,降低了TiO_2的禁带宽度和光生电子和空穴的复合率。在水热温度160℃、水热时间4 h条件下制备的TiO_2/电气石(3%)表现出最高的光催化降解罗丹明B的性能。说明TiO_2与这种有自发极化的材料复合能够有效提高其光催化性能。     

AgI/h-MoO_3异质结的构筑及其模拟燃油光催化氧化脱硫活性

利用沉积法获得了异质结AgI/h-MoO_3光催化剂,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、光电子能谱(EDS)、X射线光电子能谱(XPS)、紫外-可见漫反射吸收光谱(UV-Vis-DRS)、光致发光(PL)、电化学阻抗(EIS)等方法对其物相组成、形貌、光吸收特性、光电化学性能等进行了表征。以噻吩的正辛烷溶液模拟催化裂化(FCC)汽油为探针考察了AgI/h-MoO_3光催化氧化脱硫活性,结果表明,AgI/h-MoO_3-18异质结在催化剂浓度为1.5 g·L~(-1),可见光照射2 h后,光催化氧化脱硫活性达98%。利用XRD、XPS、UV-Vis-DRS揭示了AgI/h-MoO_3光照后生成少量的金属Ag,使其结构转变为Z型AgI/Ag/h-MoO_3,有利于光生电子(e~-)转移。利用活性物种捕获实验、循环实验研究了AgI/h-MoO_3光催化氧化脱硫机理及其稳定性,实验结果表明:AgI/h-MoO_3不仅具有较高的光催化氧化脱硫活性,而且还有良好的稳定性。     

温和条件下Fe（NO3）3／4-OH-TEMPO催化需氧氧化醇制备羰基化合物

以Fe(NO3)3·9H2O为助剂与廉价的有机小分子催化剂 4-羟基-2,2,6,6-四甲基哌啶-N-氧自由基(4-OH-TEMPO)组成催化体系.考察了该催化剂体系上分子氧驱动的氧化含有C=C, N, O和S杂原子的较宽底物范围的伯醇和仲醇氧化生成相应的醛或酮. 结果表明,该反应可在室温条件下在空气中进行,对目的产物的选择性高. 探讨了Fe(NO3)3/4-OH-TEMPO催化氧化醇的反应机理.     

微弧氧化法制备WO_3/TiO_2复合薄膜的结构及光催化性能

采用微弧氧化工艺分别在钨酸盐和磷酸盐电解液中制备了WO_3/TiO_2复合薄膜和单一的TiO_2膜(P-TiO_2),利用X射线衍射、扫描电子显微镜、紫外-可见光谱和荧光光谱对这两种膜层的结构及光物理特性进行了表征.结果表明,P-TiO_2膜由锐钛矿与金红石混合相组成,而WO_3/TiO_2膜中除锐钛矿与金红石混合相外,还含有W0O相.两种膜层表面粗糙多孔,WO_3/TiO_2膜的孔洞数量更多,分布更均匀.WO_3/TiO_2膜的光吸收范围较P-TiO_2膜略宽,但后者在紫外光区的光吸收性能更好.WO_3O/TiO_2膜的荧光发光强度比P-TiO_2的小,光生电子-空穴之间的分离效果好.与P-TiO_2膜相比,WO_3/TiO_2膜的表面酸度高,吸附有机物和羟基的能力更强.紫外光下照射2 h,WO_3/TiO_2能够降解85%罗丹明,而P-TiO_2膜只能降解23%.WO_3/Ti0_2膜的高光催化活性源于它较高的比表面积、较优的电子.空穴分离效果和较高的表面酸度.     

Cyclohexene Promoted Efficient Biomimetic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by Manganese Porphyrin under Mild Conditions

Selective oxidation of alcohols to corresponding carbonyl compounds is one of the most important processes both in academic and application research. As a kind of biomimetic catalyst, metalloporphyrins‐catalyzed aerobic oxidation of alcohols with aldehyde as hydrogen donator is gathering much attention. However, using olefins as another kind hydrogen donator for aerobic oxidation of alcohols has not been reported. In this study, a system comprising managenese porphyrin and cyclohexene for biomimetic aerobic oxidation of alcohols to carbonyl compounds was developed. The catalytic system exhibited excellent catalytic performance and selectivity towards the corresponding products for most primary and secondary alcohols under mild conditions. Based on the results obtained from experiments as well as in situ EPR (electron paramagnetic resonance) and UV‐vis spectroscopy, the role of cyclohexene was demonstrated.     

Synthesis of Nitroalkanes from Alkylhalides under Mild and Nonaqueous Conditions by Using Polymer Supported Nitrites

Alkyl halides are efficiently converted to their corresponding nitroalkanes under mild and nonaqueous conditions by using polymer supported nitrites. The polymeric reagent is regenerable.