渣油超临界萃取馏分中硫化物的分离富集研究

采用选择性氧化与色谱结合的方法分离渣油中的硫醚硫化物和噻吩硫化物,该法是基于不同类型硫的选择性氧化、氧化组分与未氧化组分间极性的差异实现的。首先用高碘酸四丁铵在不氧化噻吩硫的情况下将硫醚硫选择性氧化为高极性的亚砜,经色谱柱分离富集后,利用红外色谱和硫元素分析仪,研究了馏分中硫化物的类型分布。结果表明,在俄罗斯渣油中噻吩硫和硫醚硫的质量分数随组分变重均呈增长趋势,噻吩硫相对质量分数(指硫醚硫+噻吩硫)随馏分变重呈下降趋势,相对质量分数在70%以上,噻吩硫是俄罗斯渣油中硫的主要存在形态。     

Efficient Oxidation of Sulfide and Tertiary Amine by Molecular Oxygen/Aldehyde/Fe_2O_3 System

在温和的反应条件和催化剂Ｆｅ２Ｏ３存在下，结合使用分子氧和异戊醛，可高产率地发生硫醚氧化成亚砜和砜、叔胺氧化成氧化叔胺的反应。     

手性苄基甲基亚砜的氯过氧化物酶催化定向合成

基于氯过氧化物酶(CPO)对有机底物的手性识别功能,以CPO催化、叔丁基过氧化氢(TBHP)氧化甲基苄基硫醚合成手性R-苄基甲基亚砜,并在反应体系中引入多羟基化合物及季铵盐提高了目标产物的产率;反应主要受体系的pH值、氧化剂类型、反应时间、氧化剂/底物摩尔比,以及CPO用量等因素控制.引入多羟基化合物(甘油,PEG400,PEG600)时,R-苄基甲基亚砜的产率及ee值可分别达到65.5%和96.3%;而引入季铵盐(TEABr,TPABr,TBABr)时,其产率提高到78.2%～68.5%,ee值为95.4%～94%.UV-vis及荧光光谱分析表明反应体系中引入少量添加剂时CPO活性中心的血红素辅基暴露程度增加,底物容易接近,同时CPO的α-螺旋结构得以加强,从而有效改善了CPO的催化性能.与目前的合成方法相比,CPO酶促氧化制备手性R-苄基甲基亚砜高效、定向,酶用量极少,具有一定的产业化应用潜能.     

应用分子氧—醛—Fe2O3体系有效氧化硫醚和叔胺的研究

在温和的反应条件和催化剂Ｆｅ２Ｏ３存在下，结合使用分子氧和异戊醛，可高产率地发生硫醚氧化成亚砜和砜、叔胺氧化成氧化叔胺的反应。     

钒掺杂的钛酸钠纳米管作为多相催化剂用于室温下硫化物的氧化

合成了一种含有TiO2, Na和V的多相纳米管催化剂,采用红外光谱、X射线衍射、扫描电镜、透射电镜和N2吸附-脱附法对该催化剂的结构和织构性质进行了表征,并用于水中30%H2O2选择性氧化硫化物制备对应的亚砜。该法具有产率极高、多相体系和简便等优点,可用于含一系列官能团底物的氧化,产物分离简便。     

过硼酸钠对于有机物的氧化作用的研究 I:过硼酸钠对于芳胺和芳硫醚的氧化作用

研究了用过硼酸钠氧化邻位和对位硝基苯胺. 把胺基氧化成硝基、过硼酸钠还能氧化4-氨基-4'-硝基二苯基硫醚和2-氨基-2'-硝基二苯基硫醚. 得到4,4'-二硝基二苯砜和2,2'-二硝基二苯亚砜.     

钒掺杂的钛酸钠纳米管作为多相催化剂用于室温下硫化物的氧化（英文）

合成了一种含有TiO_2,Na和V的多相纳米管催化剂,采用红外光谱、X射线衍射、扫描电镜、透射电镜和N_2吸附-脱附法对该催化剂的结构和织构性质进行了表征,并用于水中30%H_2O_2选择性氧化硫化物制备对应的亚砜.该法具有产率极高、多相体系和简便等优点,可用于含一系列官能团底物的氧化,产物分离简便     

无催化条件下采用叔丁基过氧化氢(TBHP)选择性氧化硫醚/二硫醚至亚砜/单砜（英文）

在常见氧化剂叔丁基过氧化氢(TBHP)的存在下,成功开发了一种选择性将硫醚氧化成亚砜,将二硫醚氧化成单砜的新方法,得到一系列亚砜和单砜类化合物,收率为67%～98%.该方法具有不使用任何催化剂和添加剂、底物适用性广、反应效率高、选择性好等优点.此外,通过控制实验,提出了一种合理的自由基反应机理.     

手性类卟啉N4配体与锰络合物氧化动力学拆分消旋芳香环亚砜

以手性类卟啉N_4配体与金属锰原位络合化合物作为催化剂,环境友好型氧源H_2O_2作为氧化剂,金刚烷甲酸作为添加剂,对消旋芳香环亚砜进行了氧化动力学拆分.应用该催化体系对芳基烷基和芳基苄基类亚砜底物进行拓展,最高可获得手性亚砜产率为40%,对映体选择性为100%.与此同时,亚砜的进一步氧化产物砜的产率最高可达到72%.通过富电子亚砜与缺电子亚砜底物的竞争实验,发现此催化氧化体系更倾向于富电子亚砜.另外,克级规模的氧化动力学拆分的成功也说明了此类拆分方法在方法学上具有一定的实际应用价值.     

金属卟啉催化剂应用于均相氧化反应的研究进展

详细介绍了金属卟啉作为催化剂应用于各种均相氧化反应, 包括烷烃、烯烃、醇、醛、酚、硫化物、氮化物等化合物的氧化反应研究进展, 认为金属卟啉模拟酶催化剂在均相氧化反应中将有更大的应用前景.     

Fe(NO3)3·9H2O-catalyzed aerobic oxidation of sulfi des to sulfoxides under mild conditions with the aid of trifl uoroethanol

Selective oxidation of sulfides to sulfoxides was successfully performed by employing readily available Fe(NO3)3·9H2O as the active catalyst with oxygen as the oxidant in 2,2,2-trifluoroethanol (TFE) without the formation of sulfones. Nitrate anion could play a crucial role in promoting the reaction due to the oxidation capacity under acidic media. High yields of sulfoxides were exclusively obtained from the corresponding sulfides. Furthermore, both aromatic and aliphatic sulfides gave moderate to high yields of sulfoxides with this protocol.     

Some Comments on the Conformations of Methyl Phenyl Sulfides,Sulfoxides and Sulfones

¹³C-NMR. and He (Iα) photoelectron spectra of alkyl phenyl sulfides, sulfoxides and sulfones have been used to probe how their conformations depend on the size of the alkyl groups R. The results are interpreted to indicate that in the sulfides the S, R-bond is twisted out of the planar conformation with increasing size of the alkyl group, whereas in the sulfoxides and sulfones the preferred conformation with the S, R-bond perpendicular to the phenyl group plane seems to be independent of the size of R. These conclusions are in agreement with previous work on the alkyl phenyl sulfides and provide strong support for previous conjectures concerning the preferred conformations of alkyl phenyl sulfoxides and sulfones.     

Tetracyanoethylene oxide not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides

It was found that tetracyanoethylene oxide not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides with generation of two molecules of carbonyl cyanide. The reaction thus also functions as a new method for generation of carbonyl cyanide.     

Selective oxidation of sulfides to sulfoxides with cyanuric chloride and urea–hydrogen peroxide adduct

Although a number of methods have been developed for the selective oxidation of sulfides to sulfoxides, the need remains for alternative efficient, reliable strategies that can be generally applied to various sulfides and that use readily available reagents under mild reaction conditions. Herein, we report the use of urea–hydrogen peroxide adduct (UHP) and cyanuric chloride in CH₃CN at room temperature to convert sulfides to sulfoxides in excellent yields. In particular, this protocol produced sulfoxides with aromatic rings bearing electron-withdrawing groups in excellent yields.     

Tandem mass spectra of divalent metal ion adducts of glycosyl sulfides, sulfoxides and sulfones; distinction among stereoisomers

The tandem mass spectra of the divalent metal ion (Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Ni2+, Co2+ and Zn2+) adducts of acetylated 1,2-trans-glycosyl sulfides, sulfoxides and sulfones were examined using low energy collision-induced dissociation on a Quattro II quadrupole tandem mass spectrometer. Abundant doubly charged ions, such as [3M + Met]2+ and [2M + Met]2+, were observed with alkaline earth metal chlorides. The other ions observed were [M + MetCl]+, [M + MetOAc]+, [M + MetO2SPh]+ and [2M + MetCl]+. The deprotonated metal adducts [M + Met-H]+ were seen only in the sulfones. The divalent metal ion adducts showed characteristic fragmentation pathways for the glycosyl sulfides, sulfoxides and sulfones, depending on the site of metal attachment. The doubly charged metal ion adducts dissociate to two singly charged ions, [M + MetOAc]+ and [M - OAc]+, in the sulfides and sulfoxides. In the sulfones, the adducts dissociate to [M + MetO2SPh]+ and [M - O2SPh]+. In contrast to the alkaline earth metals, which attach to the acetoxy functions, the transition metals attach to the sulfide and sulfoxide functions. The metal chloride adducts display characteristic fragmentation for the sulfides, sulfoxides and sulfones. The glucosyl, mannosyl and galactosyl sulfides, sulfoxides and sulfones could be differentiated on the basis of the stereochemically controlled MS/MS fragmentations of the metal chloride adducts.     

THE REACTION OF ANHYDROUS HCI/CHLOROFORM WITH DIARYL SULFOXIDES

Abstract

The reaction of variously substituted diaryl sulfoxides with anhydrous HCl in chloroform was examined. The products ranged from the corresponding sulfides to mono- and dichlorinated sulfides and sulfoxides. The same reaction in the presence of phenol afforded primarily the corresponding sulfides accompanied by o- and p-chlorophenol. The latter reaction is an efficient means for deoxygenating diaryl sulfoxides. The mechanism of the reaction and the nature of the chlorinating species are discussed.     

Chiral sulfoxides from (R)-α- dimethylaminoethylferrocene

Chiral sulfoxides and sulfones of potential interest in organic synthesis are prepared by the reaction of 2-lithio-1-(dimethylaminoethyl)-ferrocene with disulfides, followed by oxidation of the sulfides thus obtained with sodium metaperiodate on alumina or with 3-chloropcrbenzoic acid. Most of the reactions, in particular oxidations of the sulfides to form the sulfoxides, proceed with high diastereoselectivity. The sulfoxides and sulfones can be isolated as pure enantiomers. Assignment of absolute configurations is based on independent synthesis together with ¹H- and ¹³C-NMR data and ORD measurements.     

Electronic and steric effects on the oxygenation of organic sulfides and sulfoxides with oxo(salen)chromium(V) complexes

The kinetics of oxygenation of several para-substituted phenyl methyl sulfides and sulfoxides with a series of 5-substituted and sterically hindered oxo(salen)chromium(V) complexes have been studied by a spectrophotometric technique. Though the reaction of sulfides follows simple second-order kinetics, sulfoxides bind strongly with the metal center of the oxidant and the oxygen atom is transferred from the oxidant-sulfoxide adduct to the substrate. The reduction potentials, E(red), of eight Cr(V) complexes correlate well with the Hammett sigma constants, and the reactivity of the metal complexes is in accordance with the E(red) values. The metal complexes carrying bulky tert-butyl groups entail steric effects. Organic sulfides follow a simple electrophilic oxidation mechanism, and the nonligated sulfoxides undergo electrophilic oxidation to sulfones using the oxidant-sulfoxide adduct as the oxidant. Sulfoxides catalyze the Cr(V)-salen complexes' oxygenation of organic sulfides, and the catalytic activity of sulfoxides is comparable to pyridine N-oxide and triphenylphosphine oxide. The rate constants obtained for the oxidation of sulfides and sulfoxides clearly indicate the operation of a pronounced electronic and steric effect in the oxygenation reaction with oxo(salen)chromium(V) complexes.     

TMSCl-promoted selective oxidation of sulfides to sulfoxides with hydrogen peroxide

Selective oxidation of sulfides to sulfoxides is achieved using H₂O₂ and TMSCl as the promotor. Aromatic and aliphatic sulfides are oxidized to sulfoxides in excellent yields and in short reaction times. Different functional groups including ketone, alkene, ester, and alcohol are tolerated.     

Formation of diaryl sulfides and sulfoxides: Synthesis,characterization and structure activity correlation studies

Abstract

The synthesis of a series of stable diarylsulfides and sulfoxides is reported. All the newly synthesized compounds were characterized by ¹H, ¹³C NMR and mass spectroscopic techniques. A detailed mechanistic study indicates that the formation of sulfoxides follows the oxidation. In addition to synthesis, characterization and mechanistic studies, the glutathione peroxidase(GPx) mimetic activity of the newly synthesized compounds is described. It is observed that the diaryl sulfides having a heterocyclic ring attached to the nitrogen atom facilitates the oxidation of the sulfur center to form the corresponding sulfoxides. The substituents attached to the nitrogen atom play an important role in the catalytic activity of the substituted diaryl sulfides. The obtained data supports for the higher antioxidant activity of diaryl sulfides than that of the corresponding sulfoxides.