Kinetics and Mechanism of Oxidation of Dimethyl Sulfoxide with Benzoyl Peroxide in Superbasic Media

Oxidation of dimethyl sulfoxide with benzoyl peroxide in some dipolar aprotic solvents and superbasic media was studied. The kinetic parameters were correlated with the main physicochemical characteristics of solvents. The oxidation rate grows with increasing donor number and polarizability of the solvent. A two-step scheme of dimethyl sulfoxide oxidation with benzoyl peroxide in superbasic media was suggested, involving preliminary cleavage of the peroxide to perbenzoate with the base. In the reaction, sodium tert-butylate is preferable over sodium hydroxide.     

Kinetics and Mechanism of Ruthenium(III) Catalyzed Oxidation of Dimethyl Sulfoxide by N-Chlorosuccinimde in Aqueous Alkaline Medium

The ruthenium(III) catalyzed oxidation of dimethyl sulfoxide by N-chlorosuccinimide (NCS) in aqueous alkaline medium is found to occur via substrate-catalyst complex formation followed by the interaction of active species of NCS viz., HOCl and the complex in a slow step to yield the products with regeneration of the catalyst. One of the products, succinimide, retards the rate of reaction. The reaction is first order in [NCS] and [Ru(III)], lower than first order in [DMSO] and of inverse fractional order in [OH^-]. A suitable mechanism is proposed and the reaction constants of individual steps involved in the mechanism have been evaluated. This revised version was published online in June 2006 with corrections to the Cover Date.     

活化二甲亚砜选择性氧化醇的反应

介绍活化二甲亚砜在醇类选择性氧化方面的反应及机理     

Activation of Hydrogen Peroxide by Acetonitrile in the Oxidation of Thioethers: Reaction Kinetics and Mechanism

Kinetics and Catalysis - The kinetics of oxidation of diethyl sulfide (Et2S) with hydrogen peroxide (H2O2) in aqueous solutions of acetonitrile (MeCN) was studied using a kinetic distribution...     

Photochemical Oxidation of MnSO4 in Dimethyl Sulfoxide in the Presence of Water

Russian Journal of Physical Chemistry A - A solution of MnSO4 in dimethyl sulfoxide is obtained at a water concentration of 0.2–0.6 M. Most of the water molecules in this solution belong to...     

二甲基亚砜防冻机理的拉曼光谱分析

采用拉曼光谱对不同体积比的二甲基亚砜(DMSO)水溶液进行测量, 并利用Origin 7.5对水的光谱带进行分峰, 求得拉曼光谱峰面积比值. 应用混合模型对实验结果进行了分析, 分析结果表明, 防冻剂二甲基亚砜与水混合时, 其SO基团与水分子的OH基团形成氢键(SO…H—O), 有效地阻止了四面体结构冰的生成, 并证实了二甲基亚砜与水的体积比为1∶1时, 防冻效果最佳.     

HPLC法测定沙河粉中的过氧化苯甲酰

采用高效液相色谱法测定沙河粉中的过氧化苯甲酰 ;选用DiamonsilC18(5μm,200×4.6mm)色谱柱 ,流动相 :0.02mol/LNH4Ac-甲醇(体积比95∶5) ;检测波长 :220nm ;流速 :1.0mL/min ;柱温 :室温 ;进样量 :10μL ;方法的线性关系良好 ,相关系数r=0.9994 ,样品的最低检出浓度为0.003g/kg,回收率为92 %～102 % ,RSD=1.1 % ;本方法对检测过氧化苯甲酰具有应用价值。     

Anthraquinone Electroreduction Mechanism in 0.1 M Tetrabutylammonium Bromide in Dimethyl Sulfoxide

Electroreduction of anthraquinone in 0.1 M tetrabutylammonium bromide in dimethyl sulfoxide is studied by cyclic voltammetry in an argon atmosphere at 373–423 K. According to steady- and non-steady-state measurements, the process involves two one-electron stages at potentials of –0.6 to –0.7 and –1.5 to –1.6 V vs. a quasi-reversible platinum electrode. The electrode material (platinum, silver, glassy carbon) barely affects the electroreduction mechanism. The process is controlled by the mass transfer rate. Anthraquinone can be reduced to mono- and diphenoxide anions. Optimum conditions for obtaining the latter are found.     

高效液相色谱法测定过氧化苯甲酰

过氧化苯甲酰已被广泛用作面粉及面粉制品的品质改良剂。它能提高其白度和贮藏性能,但若使用量过大,可使面粉制品在蒸煮过程中产生对人体有害的物质。我国GB/T2760-1996中规定其使用量为0.06g·kg-1,但无国家标准的检验方法,本文采酰在0.0～2.00mg范围内呈线性关系,相关系数为0.9998,相对标准偏差为4.66%,回收率为89.5%～118.0%。1　试验部分1.1　原理样品中过氧化苯甲酰以丙酮和乙醇溶解,在酸性介质中被碘化钾还原为苯甲酸后,测定苯甲酸即可求出过氧化苯甲酰的含量。1.2　仪器与试剂高效液相色谱仪(美国PE公司,附紫外检测器)PE4.6mm…     

Initiating Properties of Benzoyl Peroxide–Tetraalkylammonium Iodide System in Radical Chain Oxidation Reactions

Tetraalkylammonium iodides have an initiating effect on benzoyl peroxide in the oxidation of cumene. The characteristics of the kinetics of this process in low temperature oxidation have been studied.     

Low-Temperature Photolysis of Benzoyl Peroxide

Russian Journal of Physical Chemistry A - The photolysis of dry benzoyl peroxide (BP) at 77 K in the 480–236 nm range of wavelengths and an ethanol solution is studied via EPR. It is...     

二甲基亚砜和四氢呋喃对胃蛋白酶催化动力学和分子光谱的影响

为了研究二甲基亚砜(DMSO)和四氢呋喃(THF)对胃蛋白酶(Pepsin, PP)催化活性的影响及其作用本质, 测定了在这两种有机溶剂的作用下胃蛋白酶的催化活性、 动力学参数、 紫外吸收光谱、 紫外差示光谱和荧光发射光谱的变化. 结果表明, 体积分数为9%的DMSO使PP活性提高83.4%; 而体积分数为1%的THF只能使PP活性提高3.59%. 在盐酸溶液中, PP的动力学参数K_m=2.22 mg/mL, v_max=1.1×10⁶ U/mg Pro; 在9%DMSO中, 其K_m=1.50 mg/mL, v_max=0.5×10⁶ U/mg Pro; 在1%THF中的K_m=1.91 mg/mL, v_max=0.51×10⁶ U/mg Pro. 9%DMSO强烈抑制PP分子肽键的紫外吸收, 而对芳香族氨基酸无影响; 1%THF则对PP的紫外吸收光谱影响不大. 9%DMSO和1%THF都使PP的紫外差示光谱出现明显的负吸收峰和正吸收峰. 9%DMSO使酶分子的荧光发射峰向短波方向移动1 nm; 而1%THF则对其无影响. 实验结果表明, 在9%DMSO和1%THF中, PP分子的立体构象发生了变化, 使酶分子的K_m下降, 酶分子对底物的亲和力有所升高, 从而导致酶分子的催化活性有不同程度的提高.     

Development of a Metal-Free Oxidation of Alcohols with Dimethyl Sulfoxide (DMSO) Activated by Tosyl Chloride

In this article we propose an efficient metal-free method for the mild oxidation of alcohols using dimethyl sulfoxide/tosyl chloride at ambient temperature. The procedure described here is an easy and practical method for the oxidation of primary, secondary, allylic, and benzylic alcohols into their corresponding aldehydes and ketones. The notable advantages of this protocol are mild reaction conditions, good yields and selectivity, and simple workup with minimal waste containing no metallic components. The mechanism of the transformation is also investigated.     

Photopolymerization of Methyl Acrylate in Dimethyl Sulfoxide

Abstract

Methyl acrylate in dimethyl sulfoxide was polymerized by 2537 A ultraviolet light. The photo reaction exhibited zero-order kinetics for a given initial concentration and produced short chain polymers (M[Mbar]_W ～ 20,000). Low sulfur values of isolated polymers indicated no appreciable solvent incorporation during the polymerization.     

Dimethyl Sulfoxide Pivaloyl Chloride: A New Reagent for Oxidation of Alcohols to Carbonyls

An efficient procedure for conversion of alcohols to the corresponding carbonyl compounds, an alternative to the classical Swern oxidation, is described. Pivaloyl chloride is employed as a mild and inexpensive electrophile. A possible reaction mechanism is proposed.     

高效液相色谱法测定面粉中过氧化苯甲酰

由于过氧化苯甲酰具有使面粉增白、增筋及杀菌等效果 ,故面粉加工工艺中用其作为面粉改良剂。但有些面粉加工厂 ,为改善面粉的感官性状 ,以次充好 ,随意过量添加过氧化苯甲酰。而现在国内尚无测定面粉及其制品中过氧化苯甲酰的标准方法。本文对照文献 [1],试验了面粉中过氧化苯甲酰的高效液相色谱法。样品中过氧化苯甲酰用无水乙醇提取 ,用碘化钾将其还原为苯甲酸 ,ＯＤＳ Ｃ18柱分离 ,紫外检测器 2 30ｎｍ检测 ,以保留时间定性 ,峰面积定量。本法检出限为 1.0ｍｇ·Ｌ- 1,回收率大于86 5 % ,平均相对标准偏差 5 .2 % ,本法操作简便 ,能满…     

Kinetics and Mechanism of Oxidation of 1-Phenylsemicarbazide by Peroxydisulphate

Kinetics of oxidation of 1-phenylsemicarbazide (PSC) by peroxydisulphate ion (PDS) have been carried out where by the pseudo first order condition was verified at large excess of PDS concentration. The rate of the reaction was followed spectrophotometrically, The stoichiometry was found to be 1:1 where 1-phenylazoformamide is the oxidation product. The effect of acidity on the rate of oxidation was investigated for different temperatures. The parameters of activation ΔG*, ΔH* and ΔS* were computed for both hydrogen ion depedent and hydrogen ion independent reaction pathes. A free radical mechanism was proposed.