An unusual pathway of the oxidation of diethyl ether by bismuth(v) derivatives

Di(tert-butylperoxy)triphenylbismuth and the triphenylbismuth-tert-butyl hydroperoxide system transform diethyl ether into ethoxyacetic aldehyde. The latter undergoes further conversions under these reaction conditions to give the corresponding hydroxyperoxide, ethoxyacetic acid, and bismuth(III) acylates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 783–784, April, 1995.This work was financially supported by the Competition Center for Fundamental Natural Studies at Saint-Petersburg University (Grant No. 94-9.4-219).     

Preparation of Latexes with Poly(Methyl Methacrylate) Cores and Hydrophilic Polymer Shells Containing Amino Groups

Abstract

Functional latexes with poly(methyl methacrylate) (PMMA) cores and amino‐containing, water‐soluble polymer shells were synthesized via direct graft copolymerization of methyl methacrylate from water‐soluble polymers induced by a small amount of tert‐butyl hydroperoxide (TBHP) at 80°C for 2 h. Amphiphilic graft copolymers and PMMA homopolymers were generated concurrently to form highly monodispersed latexes. The effects of water‐soluble polymer containing different amino group, reaction temperature, TBHP concentration, molecular weight of the polymer and pH of the solution on conversion and grafting efficiency of the monomer and particle size were investigated. Transmission electron microscopic images of the PMMA/poly(ethyleneimine) (PEI) and PMMA/poly(allylamine) (PAA) particles clearly show well‐defined core‐shell morphologies, where PMMA cores are coated with either PEI or PAA shell. The amino‐containing polymer shells were also confirmed with zeta‐potential measurements. Furthermore, the amino‐containing latexes can be produced with a solids content up to 22 wt.%. Thus, this method provides a commercially viable route to functional latexes.     

TBHP/R4N+X– promoted hydroaroylation of dialkyl azodicarboxylates with methyl arenes,aldehydes, aryl methanols and arylmethyl chlorides

Efficient TBHP/R₄N⁺X^– promoted hydroaroylations of dialkyl azo-1,2-dicarboxylates with methyl arenes, aldehydes, aryl methanols and arylmethyl chlorides are described. These oxidation/oxygenation and hydroaroylation processes were carried out by tert-butyl hydroperoxide as terminal oxidant/oxygen source, and were catalyzed by tetrabutylammonium bromide and tricaprylmethylammonium chloride as the driving force. During this investigation, all these hydroaroylating sources were found to be highly efficient reagents without the need of any transition-metal.     

Synthesis of Cumene from Lignin by Catalytic Transformation

Cumene is an important intermediate and chemical in chemical industry.In this work,directional preparation of cumene using lignin was achieved by a three-step cascade process.The mixture aromatics were first produced by the catalytic pyrolysis of lignin at 450℃ over 1% Zn/HZSM-5 catalyst,monocyclic aromatics with the selectivity of 85.7 wt% were obtained.Then,the catalytic dealkylation of heavier aromatics resulted in benzene-rich aromatics with 93.6 wt% benzene at 600℃ over Hβ catalyst.Finally,the cumene synthesis was performed by the aromatic alkylation,giving cumene selectivity of 91.6 C-mol% using the[bmim]Cl-2AlCl₁₃ ionic liquid at room temperature for 15 min.Besides,adding a small amount of methanol to the feed can efficiently suppress the coke yield and enhance the aromatics yield.The proposed transformation potentially provides a useful route for production of cumene using renewable lignin.     

氯原子引发的甲基过氧化氢大气光化学反应

有机过氧化物在大气化学过程中起着重要作用 ,并对城市大气质量有着重要影响 ,然而 ,目前对它们大气化学行为的了解还非常不够 ,尤其缺少定量的研究。文章利用长光路傅里叶变换红外光谱 (长光路FTIR)仪原位跟踪反应进程 ,进行实验室模拟研究大气中非常重要的一种有机过氧化物 ,即甲基过氧化氢(CH3OOH ,MHP)的大气光化学反应。反应在内配有红外光多次反射镜 (White镜 )的 2 8 5L静态石英反应池中进行 ,采用氯原子 (Cl)引发反应 ,温度为 (2 92± 2 )K ,压力为 9 3× 10 4 Pa(2 0 %O2 80 %N2 )。FTIR光谱表明反应产物中主要包括甲醛 (HCHO)、甲酸 (HCOOH)、一氧化碳 (CO)和二氧化碳 (CO2 ) ,此外还有少量的甲醇 (CH3OH)生成。测定了前三种主要产物在反应 6 0min内的产率 :HCOOH和CO产率分别为 2 4 %和 6 % ;而HCHO浓度先增后减 ,浓度达到峰值时产率为 5 0 %。根据实验结果探讨了可能的反应机理 ,指出MHP是大气中HOx 自由基的储库分子 ,对整个大气光化学反应的进程有重要作用     

Synthesis and characterization of poly(methyl methacrylate)/casein nanoparticles with a well‐defined core‐shell structure

Well‐defined, core‐shell poly(methyl methacrylate) (PMMA)/casein nanoparticles, ranging from 80 to 130 nm in diameter, were prepared via a direct graft copolymerization of methyl methacrylate (MMA) from casein. The polymerization was induced by a small amount of alkyl hydroperoxide (ROOH) in water at 80 °C. Free radicals on the amino groups of casein and alkoxy radicals were generated concurrently, which initiated the graft copolymerization and homopolymerization of MMA, respectively. The presence of casein micelles promoted the emulsion polymerization of the monomer and provided particle stability. The conversion and grafting efficiency of the monomer strongly depended on the type of radical initiator, ROOH concentration, casein to MMA ratio, and reaction temperature. The graft copolymers and homopolymer of PMMA were isolated and characterized with Fourier transform infrared spectroscopy and differential scanning calorimetry. The molecular weight determination of both the grafted and homopolymer of PMMA suggested that the graft copolymerization and homopolymerization of MMA proceeded at a similar rate. The transmission electron microscopic image of the nanoparticles clearly showed a well‐defined core‐shell morphology, where PMMA cores were coated with casein shells. The casein shells were further confirmed with a zeta‐potential measurement. Finally, this synthetic method allowed us to prepare PMMA/casein nanoparticles with a solid content of up to 31%. Thus, our new process is commercially viable. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3346–3353, 2003     

聚苯乙烯的暗氧化及其反应机理研究

聚苯乙烯的暗氧化及其反应机理研究朱军民曹维孝冯新德（北京大学高分子科学与工程系北京１００８７１）关键词聚苯乙烯，异丙苯，接触电荷转移复合物（ＣＣＴ），暗氧化反应高分子材料在加工、贮存和使用的过程中，当受到大气中氧、光、热等作用时，会发生降解和交...     

Soluble polystyrene-based sulfoxide reagents for Swern oxidation reactions

Two new soluble polystyrene-based sulfoxide reagents are introduced. These polymeric reagents are used in Swern oxidation reactions where the resulting sulfide polymers are easily separated from the product by simple precipitation and filtration. The recovered reduced polymer reagents can be recycled by oxidation with tert-butyl hydroperoxide in the presence of acid. Attempts to use these reagents in a multi-polymer Swern oxidation reaction system were unsuccessful.     

Improved chromium-catalyzed allylic oxidation of Δ-steroids with t-butyl hydroperoxide

Various chromium^VI-catalyzed conditions have been tested to improve the oxidation of Δ⁵-steroids with t-BuOOH to their corresponding 5-en-7-ones. The use of PDC or the association of CrO₃ with an amine as the catalyst and CH₂Cl₂ or PhCF₃ as the solvent led usually to the best yields. A minor reaction pathway was the epoxidation of the double bond.     

皂石的合成、表征及其催化性能

用水热法合成了皂石,并用羟基铝低聚物与其交联制得AICLS。用XRD、~(27)Al和~(29)Si MASNMR及吡啶吸附量表征其晶相、结构和表面酸性。合成产物的结晶度很高。皂石中T—O—T片内四面体层上铝量可由合成条件控制,表明交联密度的柱间距与铝量有关。在异丙苯裂解反应中,AICLS的活性高于皂石,但活性衰减较慢;样品的催化裂化活性与探针分子可抵达的强酸中心数有关。