Regioselective Hydroperoxygenation of Aralkanes and α,β‐Unsaturated Carbonyl Compounds Catalyzed by N‐Hydroxyphthalimide and 2,2′‐Azobis(4‐methoxy‐2,4‐dimethylvaleronitrile)

Abstract

Aerobic oxidation of aralkanes and α,β‐unsaturated carbonyl compounds in the presence of a catalytic amount of N‐hydroxyphthalimide (NHPI) and 2,2′‐Azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) (V‐70) under 1 atmos. of oxygen at 30°C gave α‐hydroperoxyaralkanes and γ‐hydroperoxy‐α,β‐unsaturated carbonyl compounds, respectively.     

铜掺杂钙铝水滑石催化氧化异丙苯制备异丙苯过氧化氢

采用共沉淀法制备了铜掺杂钙铝水滑石Ca₄Cu _x Al-LDHs（x=0,0.1,0.3,0.5,0.8,1.0）,并对其催化异丙苯液相氧化制备异丙苯过氧化氢的活性进行了研究。采用X射线衍射、傅里叶红外光谱、扫描电子显微镜和热分析等手段对Ca₄Cu _x Al-LDHs进行了表征,制备的Ca₄Cu _x Al-LDHs保留了水滑石的片层状结构,铜的掺杂使孔径变小,比表面积增大。当进料比（催化剂/异丙苯）为7.5 mg/mL,反应温度85 ℃,氧气流速为15 mL/min,反应时间7 h,异丙苯的转化率为34.5%,异丙苯过氧化氢的选择性为86.9%,催化剂循环使用5次后,异丙苯的转化率为31.2%,异丙苯过氧化氢的选择性为83.3%。研究为异丙苯过氧化氢开发了新的催化体系。     

5-氯-2-(4-氯-苯氧基)-苯酚的合成

以对二氯苯为起始原料,经过乙酰基化、醚化、过氧乙酸氧化、水解得到5-氯-2-(4-氯-苯氧基)-苯酚,改良后的工艺使终产品收率达32.9%,醚化反应改用氢氧化钾代替碳酸钾与对氯苯酚反应制备亲核试剂,均三甲苯代替二甲苯为溶剂,醚化产物收率达到69.2%。氧化反应使用乙酸酐与过氧化氢(w=0.30)反应制备氧化剂,乙酸为溶剂,氧化反应收率达到72.7%。     

Kinetics and thermodynamics of thermal decomposition of synthetic AlPO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O

Cumene hydroperoxide (CHP) and its derivatives have caused many serious explosions and fires in Taiwan as a consequence of thermal instability, chemical contamination, and even mechanical shock. It has been employed in polymerization for producing phenol and dicumyl peroxide (DCPO). Differential scanning calorimetry (DSC) was used to analyze the thermal hazard of CHP in the presence of sodium hydroxide (NaOH), sulfuric acid (H₂SO₄), and sodium bisulfite (Na₂SO₃). Thermokinetic parameters for decomposition, such as exothermic onset temperature (T ₀ ), maximum temperature (T _max ), and enthalpy (ΔH), were obtained from the thermal curves. Isothermal microcalorimetry (thermal activity monitor, TAM) was employed to investigate the thermal hazards during CHP storage and CHP mixed with NaOH, H₂SO₄, and Na₂SO₃ under isothermal conditions in a reactor or container. Tests by TAM indicated that from 70 to 90 °C an autocatalytic reaction was apparent in the thermal curves. According to the results from the TAM test, high performance liquid chromatography (HPLC) was, in turn, adopted to analyze the result of concentration versus time. By the Arrhenius equation, the activation energy (E _a ) and rate constant (k) were calculated. Depending on the process conditions, NaOH was one of the incompatible chemicals or catalysts for CHP. When CHP is mixed with NaOH, the T ₀ is induced earlier and the reactions become more complex than for pure CHP, and the E _a is lower than for pure CHP.     

Synthesis of uracil derivatives by oxidation of Fischer tungsten-carbene uracil complexes

A study on the oxidation of Fischer tungsten-carbene uracil complexes has been carried out. Several commonly used oxidants gave results strongly influenced by the presence of substituent on nitrogen atoms. In particular, usual oxidants failed in the oxidation of 3-alkyl uracil carbene complexes. Finally, we showed that t-butyl hydroperoxide is able to oxidize successfully also 3-alkyl uracil carbene complexes and can be used as a good alternative to the other methods.     

Selective oxidation of benzylic,allylic and propargylic alcohols using dirhodium(II) tetraamidinate as catalyst and aqueous tert‐butyl hydroperoxide as oxidant

We show that the dirhodium(II) tetraamidinate complex Rh₂(Msip)₄ efficiently catalyzes the oxidation of activated secondary alcohols at only 0.1 mol% loading. In this approach, we oxidized various benzylic, allylic and propargylic alcohols to the corresponding carbonyl compounds under mild aqueous conditions using the inexpensive oxidant T‐HYDRO® (70 wt% aqueous tert‐butyl hydroperoxide). Copyright © 2015 John Wiley & Sons, Ltd.     

Intramolecular chain reaction of artemisinin oxidation

The intramolecular chain oxidation of artemisinin was analyzed using the parabolic model. The competition of the mono- and bimolecular peroxy radicals formed from artemisinin was considered. Artemisinin is predominantly oxidized via the intramolecular chain mechanism to form polyatomic hydroperoxides. This results in the situation when, under aerobic conditions, artemisinin is transformed from the monofunctional into polyfunctional initiator with several hydroperoxide groups. The enthalpy was calculated, and the activation energies and rate constants of the intramolecular reactions of the artemisinin peroxy radicals, as well as those of their bimolecular reactions with C-H, S-H, and O-H bonds of biological substrates and their analogs, were calculated in the framework of the parabolic model. A new kinetic scheme for artemisinin oxidation was proposed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 267–275, February, 2008.