电催化氧化制备苯甲醛的研究

在超声波槽中电生成纳米金属氧化物,继而以MnO2/Mn2 或金属氧化物氧化还原电对作为媒介,电催化氧化合成苯甲醛.实验表明,电流效率和苯甲醛的产率在超声的参与下有明显的提高,优化了超声电解的条件.在较高温度下反应时,有利于提高生成苯甲醛的电流效率.反应选择性较高,苯甲醛产率可达88.9%.     

Electrocatalytic Oxidation of Vitamin B6 by 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl

Introduction Nitroxides such as 2,2,6,6-tetramethylpiperidine-N- oxyl (TEMPO) are well-known stable free radicals which have been extensively used in spin labeling,1 spin trapping2 and as antioxidants.3 Nitroxides are also easy to undergo reversible one-electron oxidation to form the corresponding oxoammonium ions.4 Oxoammonium ions are mild one-electron oxidants which have been used in organic synthesis5-8 and to generate radical cations.9 We10 found recently that electrochemically generat…     

Carbon‐Supported Pt Particles as a Catalyst for Electrooxidation of Methanol and Cyclic Voltammetry Studies Under Acidic Conditions

Electrooxidation of methanol on glassy carbon (GC) electrode modified by optimum carbon supported Pt electrocatalyst (Pt‐C/GC) in acid media is investigated. The catalyst is prepared by ultrasonicating Pt/C powders in aqueous media. The activity of prepared Pt‐C/GC electrode is studied in potential range of 0–1000 mV (versus SCE) by cyclic voltammetry. The results showed that the Pt/C dispersed layer at the surface of glassy carbon electrode, behaves as an electrocatalyst for the oxidation of methanol in acid medium by optimum loading of Pt (0.2 mg cm^?2). The electrochemical properties of prepared electrode are studied under various conditions. However the effect of various parameters in the catalytic enhancement of Pt/C, such as platinum loading, sulfuric acid concentration, different scan rates, different final potentials, and medium temperature are considered and examined.     

Electrochemical and chemical oxidation of alcohols in a two-phase system using N-oxopiperidinium salt: Synthesis of 4-chlorobutanal,formylcyclopropanes, andm-phenoxybenzaldehyde

Oxidation of 4-chlorobutanol-1, cyclopropylcarbinols, andm-phenoxybenzyl alcohol with electrogenerated bromine, molecular bromine, and sodium hypochlorite using N-oxopiperidinium salt in the two-phase system CH ₂ Cl ₂ —water gave the corresponding carbonyl compounds with good yields.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 941–946, April, 1992.     

环取代基对金属化聚苯胺衍生物膜修饰电极性能的影响

通过比较聚2，5－二甲氧基苯胺（PDMAn）、聚邻甲基苯胺（POT）和聚间氯苯胺（PmClAn）膜修饰电极的氧化还原电位、沉积在这3种聚合物上的铂微粒的表面形态与晶面取向以及异丙醇在分散Pt微粒的聚苯胺膜修饰电极上的氧化行为，从电子效应和立体效应探讨了聚合物电化学性质与环取代基的关系以及不同聚合基质对Pt沉积机理和有催化性能的影响,结果表明，在硫酸溶液中PDMAn膜修饰电极的氧化还原电位最负、POT次之、PmClAn最正，Pt在PDMAn和POT膜上的电沉积机理与在PmClAn膜上的不同，聚合物膜上沉积的Pt微粒呈现（200)晶面择优取向，其中POT膜上择优取向度最大，PDMAn次之，Pm-ClAn最小，异丙醇在金属化聚合物膜电极上的氧化电位取决于聚苯胺的本质，在POT膜修饰电极上异丙醇的电氧化主要发生在POT的活性电位区，而在PDMAn与PmClAn膜上的电氧化则主要发生在Pt上的氧化电位区，说明聚合物膜不仅作为Pt微粒的分散介质，而且本身有产生催化作用。     

Metal- and Additive-Free Electrochemical Oxidation of Benzylic C−X Bonds to Carbonyl Groups

A scalable electrochemical strategy for oxidation of various benzylic C−X bonds to carbonyl groups was achieved. The protocol runs under mild reaction conditions and air atmosphere in a simple undivided electrolysis cell, H₂O as oxygen source, and cheap graphite plates as both anode and cathode. In addition, the electrolysis strategy features good functional groups tolerance for selectively generating structure versatile ketones, aldehydes, and esters.     

Ti/Sb2O5-SnO2/PbO2电极电催化氧化对氨基苯酚

以电沉积法制备的Ti／Sb2O5-SnO2／PbO2电极作阳极,恒电流电解水溶液中的对氨基苯酚（PAP）,利用紫外光谱探讨了对氨基苯酚电催化氧化的反应历程,系统地考察了电解时间、反应温度,pH值、电流密度以及对氨基苯酚初始浓度对COD去除率的影响,提出了电催化氧化对氨基苯酚的最佳条件．结果表明,对氨基苯酚电催化反应为逐级氧化历程,主要中间产物为苯醌、丁烯二酸和草酸,最终产物为CO2和水．20℃,对初始浓度10mg／L的对氨基苯酚水溶液（pH=6）,恒定电流密度100mA／cm^2,电解1h,COD去除率可达98．5％．该方法作为废水中对氨基苯酚的最小化处理．具有良好的应用前景．     

Electrosynthesis of diazene oxides under oxidation of nitramine anions at Pt in MeCN in the presence of nitrosobenzene

The electrooxidation of anions of primary nitramine salts RNNO ₂ ⁻ M⁺ (R=Me, Et, methoxyfurazanyl; M⁺=Bu₄N⁺, Li⁺, Na⁺) at a Pt anode in the presence of nitrosobenzene in divided and undivided cells was studied by potentio-and amperostatic electrolysis. Solutions of alkali metals and tetrabutylammonium salt in anhydrous MeCN were used as supporting electrolytes. Electrolysis can result in the formation of the corresponding diazene oxide, whose yield depends on the nature of the cation of the supporting electrolyte. In an undivided cell, the yield of diazene oxide increases owing to the regeneration of nitramine anions due to cathodic deprotonation of the nonionized form. The latter is formed by the stabilization of some radical intermediates by the elimination of hydrogen atoms from the components of the medium. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1427–1431, August, 2000.     

Electrocatalytic Oxidation of Formaldehyde on Copper Oxide Nano-crystalline Modified Glassy Carbon Electrode

This research found a cheap and efficient catalyst for electrooxidation of formaldehyde (HCHO). A CuO nano‐crystalline modified glassy carbon electrode (GCE) was fabricated and had an excellent electrocatalytic activity towards the oxidation of HCHO. Both the effect of potential scan rate and the effect of HCHO concentration on the electrocatalytic oxidation performance of the electrode were investigated. The amperometric current response of the electrode was proportional to HCHO concentration in the range of 1.0 µmol·L^?1–10.0 mmol·L^?1 with a detection limit (s/n=3) of 0.25 µmol·L^?1. The electrode was stable, showing the CuO nano‐crystlline is promising for applications in fuel cells and electrochemical sensors.     

硼掺杂碳化硅负载Pt催化剂的甲醇电催化氧化性能

以硼掺杂碳化硅(B0.1SiC)为载体,采用循环伏安法在B0.1SiC载体上电沉积Pt纳米粒子制备了Pt/B0.1SiC催化剂。利用X射线光电子能谱、X射线衍射、氮气吸附-脱附、扫描电镜及透射电镜等测试方法对催化剂的晶型、表面性质及形貌进行了表征。结果表明,硼原子掺杂进入SiC晶格并取代了Si位点,使B0.1SiC载体的导电性增强;Pt纳米粒子均匀地分布在B0.1SiC载体上,平均粒径为2.7 nm。与相同条件下制备的Pt/SiC催化剂相比,Pt/B0.1SiC具有较大的电化学活性表面积、更高的甲醇催化氧化活性和稳定性。