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.     

Reaction hazard analysis for the thermal decomposition of cumene hydroperoxide in the presence of sodium hydroxide

Organic peroxides have caused many serious explosions and fires that were promoted by thermal instability, chemical pollutants, and even mechanical shock. Cumene hydroperoxide (CHP) has been employed in polymerization and for producing phenol and dicumyl peroxide (DCPO). Differential scanning calorimetry (DSC) has been used to assess the thermal hazards associated with CHP contacting sodium hydroxide (NaOH). Thermokinetic parameters, such as exothermic onset temperature (T ₀), peak temperature (T _max), and enthalpy (ΔH) were obtained. Experimental data were obtained using DSC and curve fitting using thermal safety software (TSS) was employed to obtain the kinetic parameters. Isothermal microcalorimetry (thermal activity monitor, TAM) was used to investigate the thermal hazards associated with storing of CHP and CHP mixed with NaOH under isothermal conditions. TAM showed that in the temperature range from 70 to 90°C an autocatalytic reaction occurs. This was apparent in the thermal curves. Depending on the operating conditions, NaOH may be one of the chemicals or catalysts incompatible with CHP. When CHP was mixed with NaOH, the T ₀ is lower and reactions become more complex than those associated with assessment of the decomposition of the pure peroxide. The data by curve fitting indicated that the activation energy (E _a) for the induced decomposition is smaller than that for decomposition of CHP in the absence of hydroxide.     

钨酸钠/过氧化氢体系对葡甲苷伯羟基的选择催化氧化

采用钨酸钠/过氧化氢体系对甲基葡萄糖苷的伯羟基进行选择催化氧化制备葡萄糖醛酸及其内酯,考察了不同催化氧化工艺条件对反应收率的影响,产物用HPLC检测,同时对反应机理进行了初步探讨。 结果表明, 该体系对葡甲苷伯羟基的氧化具有较好的催化活性和反应选择性,葡萄糖醛酸及其内酯总收率可达到74.07%。 与传统的淀粉硝酸氧化法工艺相比,该方法具有资源节约、环境友好的特点。     

Synthesis and characterization of a self-crosslinkable polymer from cardanol: Autooxidation of poly(cardanyl acrylate) to crosslinked film

Cardanyl acrylate (CA), a monomer that yields crosslinkable copolymers, was synthesized by the reaction of cardanol with acryloyl chloride. A linear polymer was obtained by solution polymerization of the monomer in toluene using 0.8% azobisisobutyronitrile as initiator. Upon removal of solvent, the polymer undergoes crosslinking on exposure to air (or UV light) to give an insoluble transparent film. However, in bulk and suspension polymerization the polymer undergoes in situ crosslinking in the absence of any crosslinking agent. The polymer was characterized by IR, NMR, DSC, and GPC. The crosslinking reaction of soluble polymer on exposure to air at ambient conditions was explained by the hydroperoxide theory. © 1993 John Wiley & Sons, Inc.     

片状纳米CuO用于苯乙烯氧化反应的研究

苯甲醛又称安息香醛,是医药、染料、香料工业的一种重要的中间体,主要用于制造品绿、月桂醛、月桂酸等;也有时用作有机溶剂,测定臭氧及位于羰基旁边的亚甲基及检定酚和生物碱的试剂.传统的工业生产方法是以石油化工中的甲苯为原料,经氯化生成二氯化苄,再经酸性或碱性水解、真空     

Synthesis and characterization of poly (2-vinylpridine)-b-poly (t-butyl methacrylate)

The synthesis of well defined and monodisperse (M_w/M_n ≤ 1.2) narrow molecular weight distribution poly (2-vinylpyridine)-poly (t-butyl methacrylate) (P2VP-PTBMA) AB block copolymers is carried out by initiation of 2-vinylpyridine polymerization by 1,1-diphenylhexyllithium in THF at-78°C, followed by addition of TBMA and termination at ?78°C using MeOH. The formation of the BAB block copolymer is carried out in a similar fashion except that 1,4-dilithio-1,1,4,4-tetraphenylbutane is used as initiator. The corresponding synthesis of P2VP-PMMA block copolymers is carried in a similar manner, except that 1-2 equivalents of TBMA is used to end-functionalize the living P2VP before the addition of MMA. Without the addition of TBMA, trimodal molecular weight distributions in P2VP-b-PMMA are obtained. All the block copolymers are characterized by Size Exclusion Chromatography (SEC), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC). © 1994 John Wiley & Sons, Inc.     

ACTH(6–9)PGP Peptide Protects SH-SY5Y Cells from H2O2, tert-Butyl Hydroperoxide,and Cyanide Cytotoxicity via Stimulation of Proliferation and Induction of Prosurvival-Related Genes

Stabilized melanocortin analog peptide ACTH(6–9)PGP (HFRWPGP) possesses a wide range of neuroprotective activities. However, its mechanism of action remains poorly understood. In this paper, we present a study of the proproliferative and cytoprotective activity of the adrenocorticotropic hormone fragment 6–9 (HFRW) linked with the peptide prolyine–glycyl–proline on the SH-SY5Y cells in the model of oxidative stress-related toxicity. The peptide dose-dependently protected cells from H₂O₂, tert-butyl hydroperoxide, and KCN and demonstrated proproliferative activity. The mechanism of its action was the modulation of proliferation-related NF-κB genes and stimulation of prosurvival NRF2-gene-related pathway, as well as a decrease in apoptosis.     

Coordination Compounds of Strontium: Syntheses,Characterizations, and Crystal Structures of [Sr(μ-ONc)2(HONc)4]2 and Sr5(μ4-O)(μ3-ONep)4(μ-ONep)4(HONep)(solv)4 (ONc = O2CCH2CMe3; Nep = CH2CMe3; solv = Tetrahydrofuran or 1-Methyl-Imidazole)

Abstract

We have synthesized and characterized two novel Sr compounds: [Sr(μ-ONc)₂(HONc)₄]₂ (1, ONc ? O₂CCH₂CMe₃), and Sr₅(μ_?O)(μ₃?ONep)₄(μ?ONep)₄(HONep)(solv)₄ [ONep ? OCH₂CMe₃, solv = tetrahydrofuran (THF), 2a; 1-methyl-imidazole (Melm), 2b], that demonstrate increased solubility in comparison to the commercially available Sr precursors. The two metal centers of 1 share four unidentate bridging μ-ONc ligands and complete their octahedral geometry through coordination of four monodentate terminal HONc ligands. The structural arrangement of the central core of 2a and 2b are identical, wherein four octahedral Sr atoms are arranged in a square geometry around a μ₄-O ligand. An additional seven-coordinated Sr atom sits directly atop the μ₄-O to form a square-pyramidal arrangement of the Sr atoms, but the apical Sr-O distance is too long to be considered a bond. In solution, compound 1 is disrupted forming a monomer but 2a and 2b retain their structures.     

Thermal hazards evaluation of cumene hydroperoxide mixed with its derivatives

Over 90% of the cumene hydroperoxide (CHP) produced in the world is applied in the production of phenol and acetone. The additional applications were used as a catalyst, a curing agent, and as an initiator for polymerization. Many previous studies from open literature have verified and employed various aspects of the thermal decomposition and thermokinetics of CHP reactions. An isothermal microcalorimeter (thermal activity monitor III, TAM III), and a thermal dynamic calorimetry (differential scanning calorimetry, DSC) were used to resolve the exothermic behaviors, such as exothermic onset temperature (T ₀), heat power, heat of decomposition (ΔH _d), self-heating rate, peak temperature of reaction system, time to maximum rate (TMR), etc. Furthermore, Fourier transform infrared (FT-IR) spectrometry was used to analyze the CHP products with its derivatives at 150 °C. This study will assess and validate the thermal hazards of CHP and incompatible reactions of CHP mixed with its derivatives, such as acetonphenone (AP), and dimethylphenyl carbinol (DMPC), that are essential to process safety design.