离子迁移谱定量检测复杂基质中新型炸药六亚甲基三过氧化二胺

六亚甲基三过氧化二胺( Hexamethylene triperoxide diamine, HMTD)是一种新型有机过氧化爆炸物,由于原料易得、制备方法简单,常被用于恐怖袭击和犯罪活动中。本实验基于非放射性电离源真空紫外灯( VUV)发展了一种试剂分子辅助灯电离正离子迁移谱技术,通过优化筛选试剂分子,最终选择丙酮作为HMTD定量检测的试剂分子。利用质谱对丙酮的反应试剂离子和HMTD的产物离子进行了离子归属,确定反应试剂离子为丙酮二聚体离子 m/z 117[( CH3)2 CO ]2 H+, HMTD 的产物离子为其质子化的分子离子m/z 209[ HMTD+H]+。在迁移管和热解析温度120℃的条件下,利用HMTD最大信号强度和第10 s的信号强度对其标准样品进行定量检测,线性范围分别为5~50 ng/μL和5~100 ng/μL,检出限分别可达0.2和0.3 ng/μL。化妆品如香水等常常干扰和抑制离子迁移谱测量,发展在香水基质中HMTD的现场快速筛查和检测方法具有现实意义。将这两种定量方法应用于3种不同品牌香水样品中HMTD的定量检测,对比发现利用HMTD第10 s的信号强度进行定量具有较好的回收率和准确性,该方法适用于复杂基质中HMTD的准确快速定量检测。     

Osmium-catalyzed asymmetric dihydroxylation by carbon dioxide-activated hydrogen peroxide and N-methylmorpholine

An improved process has been developed for the osmium-catalyzed dihydroxylation of olefins via in situ formation of NMO from NMM using CO₂ catalysis and H₂O₂. All olefins examined were selectively cis-dihydroxylated to their corresponding diols in good to excellent yields, and by the use of chiral ligands, high enantiomeric excesses were obtained.     

铁改性的HMS分子筛催化苯酚羟基化反应合成二酚

邻苯二酚和对苯二酚是重要的精细化工中间体,在各个行业中具有广泛的应用。苯酚与过氧化氢反应合成苯二酚是一条反应条件温和、环境友好的合成路线,该合成路线的关键是催化剂的选择和反应条件的优化。本文以铁改性的HMS分子筛为催化剂,研究了金属负载量、催化剂使用量、反应温度、反应时间等因素对催化性能的影响,优化了反应条件。以水为溶剂,n(Fe)∶n(Si)=0.04,n(苯酚)∶n(H2O2)=2∶1,反应温度50℃,催化剂用量0.1g,反应4h,苯酚的转化率达45.5%,苯二酚选择性为94.9%。N2吸附-脱附结果表明,Fe/HMS具有良好的介孔结构,铁进入HMS材料的骨架中,并且催化剂具有良好的稳定性,循环使用后骨架保持完整。     

A unique peroxide formation based on the Mn(III)-catalyzed aerobic oxidation

The autoxidation of a mixture of 1,1-diarylsubstituted alkenes 4 and 4-hydroxy-1H-quinolin-2-ones 5 in the presence of a catalytic amount of manganese(III) acetate dihydrate in air gave 3,3-bis(2-hydroperoxyethyl)-1H-quinoline-2,4-diones 6 in 31-91% yields together with [4.4.3]propellane-type cyclic peroxides 7 (10-34%). A similar aerobic oxidation of 3-substituted quinolinones 8 yielded cyclic peroxide derivatives 9 and/or 3-hydroperoxyethylated quinolinediones 10 depending on the substituent. The structures of the bis(hydroperoxide) 6 (R¹=Me, Ar=4-ClC₆H₄) and the [4.4.3]propellane 7 (R¹=Me, Ar=Ph) have been corroborated by X-ray crystallography.     

One-step synthesis of pentavalent triphenylantimony derivatives Ph3Sb(OSiR3)2, Ph3Sb(OCH2CH2)2NH and Ph3Sb(OCH2CH2NMe2)2: X-ray molecular structure of Ph3Sb(OSiMe3)2

Pentavalent bis(triorganosiloxy)triphenylantimony derivatives, Ph₃Sb(OSiR₃)₂ (R = Me, Ph), were synthesized by reaction of triphenylantimony with trimethyl- or triphenylsilanol in the presence of tert-butylhydroperoxide by the mild reaction conditions (0-5 °C, 2 h). The reaction of triphenylantimony with diethanolamine in the presence of tert-butylhydroperoxide gave the cyclic compound Ph₃Sb(OCH₂CH₂)₂NH. The mixture of Ph₃SbO and Ph₃Sb(OCH₂CH₂NMe₂)₂ was obtained by the reaction of triphenylantimony with 2-(N,N-dimethylamino)ethanol in the presence of tert-butylhydroperoxide.     

Surface modification of LDPE film by CO2 pulsed laser irradiation

The influence of the pulsed CO₂ laser irradiation on the surface structure of the LDPE film was investigated. Significant changes were observed on the surface of laser treated films as it was verified by the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy and contact angle-measurement. Formation of polar functional groups onto the LDPE surfaces exhibited by the ATR-FTIR spectra was shown to be strongly dependent on the number of the CO₂ laser pulses. The intensity of the polar groups increased with increasing the number of pulses up to two and then slightly decreased at three laser pulses. This was also confirmed with the contact angle measurements in which the sample subjected to two laser pulses showed the highest wettability i.e. the lowest water drop contact angle. The concentration of peroxide groups formed on the surface of the laser treated films was determined quantitatively by UV spectroscopic method using iodide procedure. The latter results showed a similar trend with the results obtained using FTIR spectroscopy.     

Differential selectivity in electrochemical oxidation of ascorbic acid and hydrogen peroxide at the surface of functionalized ormosil-modified electrodes

Functionalized ormosil-modified electrodes have been developed for electroanalytical applications. The functionalized ormosil-modified electrodes are made by encapsulating potassium ferricyanide/potassium ferrocyanide within ormosil film derived from an optimum composition of 3-aminopropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane and phenyltrimethoxy silane in acidic medium in absence of Nafion/crown ether (system 1), in the presence of Nafion (system 2) and in the presence of dibenzo-18-crown-6 (system 3). Another modified electrode (system 4) is also developed using the reaction product of potassium ferricyanide, 3-aminopropyltrimethoxysilane and either tetrahydrofuran (THF) or cyclohexanone followed by ormosil formation in the presence of 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane and phenyltrimethoxy silane in acidic medium. The electrochemical oxidation of hydrogen peroxide and ascorbic acid conducted at the surface of these four types of functionalized electrodes shows very interesting observations on the selective sensing of ascorbic acid and peroxide. The results based on cyclic voltammetry justify the relative performances on the kinetics of hydrogen peroxide oxidation and reduction. System 3 shows relatively much better oxidation kinetics of hydrogen peroxide as compared to other three systems with relatively weak reduction kinetics whereas system 4 shows relatively faster reduction kinetics of hydrogen peroxide as compared to other three systems. Similarly system 4 shows excellent response to ascorbic acid whereas system 3 shows insensitivity to ascorbic acid under similar experimental conditions. Typical response curve for the analysis of hydrogen peroxide and ascorbic acid using system 3 and system 4 respectively are reported. The results show that system 3 is the best for probing hydrogen peroxide with lowest detection limit of 0.5 μM without any interference from ascorbic acid as commonly encountered using many conventional and chemically modified electrodes.     

Radical addition of RFI to alkenylsuccinic anhydrides and gem-substituted alkenyl triesters : Zinc and radical induced, or spontaneous radical cyclization, of the δ-iodoalkanoic esters to γ-lactones

Radical addition of R_FI to alkenylsuccinic anhydrides affords ω-(perfluoroalkyl)-δ-iodoalkyl-2-butane-1,4-dioc acid anhydrides, and these adducts are reductively dehalogenated and esterified by zinc and acid in ethanol without lactonization. However, the R_FI adducts react with KOH in ethanol to give the alkenyl half esters (but no γ-lactone), which convert to the γ-lactones by acid catalysis. When treated with water, ethanol, Zn and 48% HBr, the R_FI adduct from but-3-en-2-yl-succinic anhydride converts to the iodo half ester, R_FCH₂CHICH(CH₃)CH(CO₂H)CH₂CO₂Et, which undergoes Zn induced (S_Hi) conversion to γ-lactone. R_FI (AIBN) and the triester CH₂CHCH₂C(CO₂Et)₂CH₂CO₂Et yield R_FCH₂CHICH₂C(CO₂Et)₂CH₂CO₂Et (95%). When heated to 140 °C, the adduct loses iodoethane.and cyclizes to diester γ-lactones (94%). With benzoyl peroxide, R_FI and the triester at 99 °C, spontaneous radical cyclization of the adduct to lactone occurs. Evidently, the gem-disubstituted triester readily forms a five-membered lactone as a consequence of steric compression in the open chain form.     

Similarities and differences of epoxide, aldehyde and peroxide initiators for Cp2TiCl-catalyzed styrene living radical polymerizations

Cp₂TiCl is the first example of a single electron transfer (SET) agent that both provides initiating radicals from three different types of functionalities (i.e. radical ring opening of epoxides and reduction of aldehydes and peroxides) and doubles as mediator for the living radical polymerization of styrene (St) by reversibly endcapping the growing polymer chains. An initiator (I) comparison was performed using 1,4-butanediol diglycidyl ether (BDE), benzaldehyde (BA) and benzoyl peroxide (BPO) as models. The investigation of the effect of reaction variables was carried out over a wide range of experimental conditions ([Cp₂TiCl₂]/[I] = 0.5/1-4/1; [Zn]/[Cp₂TiCl₂] = 0.5/1-3/1, [St]/[I] = 50/1-400/1 and T = 60-130 °C) to reveal living polymerization features such as a linear dependence of molecular weight on conversion and narrow molecular weight distribution (M_w/M_n) for each initiator class. However, progressively lower polydispersities and larger initiator efficiencies are obtained with increasing the [Cp₂TiCl₂]/[I] and [Zn]/[Cp₂TiCl₂] ratios and with decreasing temperature. Accordingly, optimum conditions correspond to [St]/[I]/[Cp₂TiCl₂]/[Zn] = [50-200]/[1]/[2-3]/[4-6] at 70-90 °C. By contrast to peroxides, aldehydes and the more reactive epoxides provide alcohol end groups useful in block or graft copolymers synthesis.