- Synthesis and biological activity of novel (Z)- and (E)-verbenone oxime esters
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Twenty-seven (Z)- and (E)-verbenone derivatives bearing an oxime ester moiety were designed and synthesized in search of novel bioactive molecules. Their structures were confirmed by UV-Vis, FTIR, NMR, ESI-MS, and elemental analysis. The antifungal and herbicidal activities of the target compounds were preliminarily evaluated. As a result, compound (E)-4n (R = b-pyridyl) exhibited excellent antifungal activity with growth inhibition percentages of 92.2%, 80.0% and 76.3% against Alternaria solani, Physalospora piricola, and Cercospora arachidicola at 50 g/mL, showing comparable or better antifungal activity than the commercial fungicide chlorothalonil with growth inhibition of 96.1%, 75.0% and 73.3%, respectively, and 1.7 5.5-fold more growth inhibition than its stereoisomer (Z)-4n (R = b-pyridyl) with inhibition rates of 22.6%, 28.6% and 43.7%, respectively. In addition, seven compounds displayed significant growth inhibition activity of over 90% against the root of rape (Brassica campestris) at 100 g/mL, exhibiting much better herbicidal activity than the commercial herbicide flumioxazin with a 63.0% growth inhibition. Among these seven compounds, compound (E)-4n (R = b-pyridyl) inhibited growth by 92.1%, which was 1.7-fold more than its stereoisomer (Z)-4n (R = b-pyridyl) which inhibited growth by 54.0%.
- Hu, Qiong,Lin, Gui-Shan,Duan, Wen-Gui,Huang, Min,Lei, Fu-Hou
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Read Online
- Synthesis of (-)-3-carene-2,5-dione via allylic oxidation of (+)-3-carene
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Activated carbon-supported CuCl2 (CuCl2/AC) is a heterogeneous catalyst for the liquid-phase selective allylic oxidation of (+)-3-carene with tert-butyl hydroperoxide (TBHP) and O2 to produce (-)-3-carene-2,5-dione. The possible reaction mechanism and the effects of different factors on the allylic oxidation were investigated. The optimal conditions are as follows: reaction temperature, 45 °C; molar ratio of CuCl2 to (+)-3-carene, 1%; volume ratio of (+)-3-carene to TBHP, 1:3; and reaction time, 12 h. Under the optimal conditions, the conversion of (+)-3-carene reached 100%, whereas the selectivity for (-)-3-carene-2,5-dione reached 78%. The CuCl2/AC catalyst was characterized via X-ray diffraction, and the chemical structure of the target compound was identified via infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, mass spectrometry, and optical analysis.
- Sun, Xiaoling,Zhao, Xiaoyan,Jiang, Ying,Xu, Bochun
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- Individual stereoisomers of verbenol and verbenone express bioactive features
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Naturally occurring terpene core compounds have been used extensively in both pharmaceutical and cosmetic industry. However, since chirality of these compounds has profound influence on the level of their bioactivity, the aim of the present study was to a
- Ivanov, Marija,Kovalenko, Vitaly,Svirid, Anastasia,Kosti?, Marina,Petrovi?, Jovana,Stojkovi?, Dejan
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- Development of rapid and selective epoxidation of α-pinene using single-step addition of H2O2in an organic solvent-free process
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This study reports substantial improvement in the process for oxidising α-pinene, using environmentally friendly H2O2 at high atom economy (～93%) and selectivity to α-pinene oxide (100%). The epoxidation of α-pinene with H2O2 was catalysed by tungsten-based polyoxometalates without any solvent. The variables in the screening parameters were temperatures (30-70 °C), oxidant amount (100-200 mol%), acid concentrations (0.02-0.09 M) and solvent types (i.e., 1,2-dichloroethane, toluene, p-cymene and acetonitrile). Screening the process parameters revealed that almost 100% selective epoxidation of α-pinene to α-pinene oxide was possible with negligible side product formation within a short reaction time (～20 min), using process conditions of a 50 °C temperature in the absence of solvent and α-pinene/H2O2/catalyst molar ratio of 5?:?1?:?0.01. A kinetic investigation showed that the reaction was first-order for α-pinene and catalyst concentration, and a fractional order (～0.5) for H2O2 concentration. The activation energy (Ea) for the epoxidation of α-pinene was ～35 kJ mol-1. The advantages of the epoxidation reported here are that the reaction could be performed isothermally in an organic solvent-free environment to enhance the reaction rate, achieving nearly 100% selectivity to α-pinene oxide.
- Eze, Valentine C.,Harvey, Adam P.,López Fernández, Ana María,Mukhtar Gunam Resul, Mohamad Faiz,Rehman, Abdul
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p. 33027 - 33035
(2021/12/07)
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- Cubic CuxZrO100-x as an efficient and selective catalyst for the oxidation of aromatics active methyl, alcohol, and amine groups
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The local structure of a supported active metal plays a vital role in determining the desired product's selectivity in heterogeneous catalysis. Herein, we have developed a simple protocol for the synthesis of Cu doped on cubic ZrO2 mixed metal oxide catalysts and used it for the selective oxidation of various functional groups. The catalyst was synthesized by varying the wt.% of Cu (1–20%) on ZrO2 by co-precipitation, followed by hydrothermal treatment. The X-ray diffraction pattern of the catalysts confirmed the formation of the cubic phase of ZrO2, and the growth of CuO occurred along the (1 1 1) plane. The microscopy analysis revealed the uniform distribution of Cu on the ZrO2 surface, while XPS analysis confirmed the presence of copper in the +2 oxidation state. The synthesized catalyst with 2 wt% loading of Cu on ZrO2 showed excellent liquid-phase oxidation properties and gave good to best conversion of active methyl groups, alcohols, and amines with high selectivities to corresponding ketones, aldehydes, and amides, respectively, under milder reaction conditions. Furthermore, the synthesized catalyst showed a broader substrate scope for the various substituted active methyl groups, alcohols, and amines with good conversion and selectivity.
- Bankar, Balasaheb D.,Advani, Jacky H.,Biradar, Ankush V.
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- Stereospecific synthesis of S-(?)-trans-verbenol and its antipode by inversion of sterically hindered alcohols
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S-(?)-trans-Verbenol (1) and its antipode, R-(+)-trans-verbenol (1′) have been confirmed as the critical pheromone components of bark beetles. Synthesis of these two active secondary alcohols (1 and 1′) from commercially available starting materials S-α-pinene and R-α-pinene was reported. The key steps were mainly depended on the effective SN2 stereo-inversion of the hydroxy group of sterically hindered alcohols (3 and 3′), using Mitsunobu reaction or hydrolysis of mesylate ester, alternatively. Our results provide a new and stereo-selectivity way to obtain optically active insect pheromones.
- Fang, Jia-Xing,Kong, Xiang-Bo,Liu, Fu,Zhang, Su-Fang,Zhang, Zhen
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- Selective Allylic Oxidation of Terpenic Olefins Using Co-Ag Supported on SiO2 as a Novel, Efficient, and Recyclable Catalyst
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Co-Ag supported on the SiO2 catalyst was synthesized by the sol-gel method and characterized using XRD, FT-IR, TG-DTG, BET, CV, and SEM/EDX analysis. The catalytic performance of the resulting catalyst was examined by the oxidation of mono and sesquiterpenic olefins using hydrogen peroxide and tert-butyl peroxide as oxidant agents. Various parameters such as catalyst amount, temperature, and solvents have been studied. The Co-Ag supported on the SiO2 catalyst showed a high activity, selectivity, and recyclability for the selected oxidation reaction.
- Aberkouks, Abderrazak,Mekkaoui, Ayoub Abdelkader,Ait Ali, Mustapha,El Firdoussi, Larbi,El Houssame, Soufiane
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- A Simple, Mild and General Oxidation of Alcohols to Aldehydes or Ketones by SO2F2/K2CO3 Using DMSO as Solvent and Oxidant
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A practical, general and mild oxidation of primary and secondary alcohols to carbonyl compounds proceeds in yields of up to 99% using SO2F2 as electrophile in DMSO as both the oxidant and the solvent at ambient temperature. No moisture- and oxygen-free conditions are required. Stoichiometric amount of inexpensive K2CO3, which generates easy to separate by-products, is used as the base. Thus, 5-gram scale runs proceeded in nearly quantitative yields by a simple filtration as the work-up. The use of a polar solvent such as DMSO, which usually promotes competing Pummerer rearrangement, is also noteworthy. This protocol is compatible with a variety of common N-, O-, and S-functional groups on (hetero)arene, alkene and alkyne substrates (68 examples). The protocol was applied (99% yield) to a formal synthesis of the important cholesterol-lowering drug Rosuvastatin. (Figure presented.).
- Zha, Gao-Feng,Fang, Wan-Yin,Leng, Jing,Qin, Hua-Li
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supporting information
p. 2262 - 2267
(2019/04/17)
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- A Cu-Doped ZIF-8 metal organic framework as a heterogeneous solid catalyst for aerobic oxidation of benzylic hydrocarbons
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Mixed-metal metal organic frameworks have received considerable attention in recent years and it has been shown that the activity of the parent metal organic framework (MOF) is often enhanced upon doping with external metal ions within the framework. In this context, Cu2+ ions with different loadings were incorporated within the ZIF-8 framework to obtain a series of Cu-doped ZIF-8 materials and their activity was examined in the aerobic oxidation of hydrocarbons. The as-synthesized Cu-doped solids were characterized by powder X-ray diffraction (XRD), ultraviolet diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM), Fourier Transform infrared (FT-IR), electron paramagnetic resonance (EPR) and inductively coupled plasma (ICP) analysis. The experimental results revealed that the activity of Cu-doped ZIF-8 is much higher than that of the parent ZIF-8 in all the tested substrates at 120 °C. Furthermore, the activity of the Cu-doped ZIF-8 with the highest Cu loading was eight fold higher than that of the parent ZIF-8 in the aerobic oxidation of cyclooctane (1) at 120 °C with more than 80% selectivity to the corresponding cyclooctanol/cyclooctanone (ol/one) mixture. Cu-doped ZIF-8 was reused two times with no significant drop in its activity under identical conditions. Furthermore, comparison of the two times reused solid with that of the fresh solid by powder XRD and SEM analysis revealed identical structural integrity and morphology, respectively during the oxidation reactions.
- Nagarjun, Nagarathinam,Dhakshinamoorthy, Amarajothi
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p. 18702 - 18712
(2019/12/09)
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- Oxy-functionalization of olefins with neat and heterogenized binuclear V(IV)O and Fe(II)complexes: Effect of steric hindrance on product selectivity and output in homogeneous and heterogeneous phase
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Neat {[VO(sal2bz)]2; [Fe(sal2bz)(H2O)2]2·2H2O} and zeolite-Y immobilized {[VO(sal2bz)]2-Y; [Fe(sal2bz)(H2O)2]2-Y} binuclear complexes have been prepared and characterized by spectroscopic techniques (IR, UV–vis), elemental analyses (CHN, ICP-OES), thermal study (TGA), scanning electron micrograph (SEM), adsorption study (BET)and X-ray diffraction (XRD)patterns. Neat (homogeneous)and immobilized (heterogeneous)complexes were employed as catalysts in the oxidation of olefins, namely, cyclohexene, limonene and α-pinene in the presence of 30% hydrogen peroxide. 100% conversion of cyclohexene and α-pinene was obtained while limonene was oxidized up to 90%. Homogeneous catalysts showed highly selective result as neat [VO(sal2bz)]2 complex has provided 87% cyclohexane-1,2-diol and neat [Fe(sal2bz)(H2O)2]2·2H2O complex has provided 79% verbenone in oxidation of cyclohexene and α-pinene, respectively. We have observed that due to steric hindrance, formation of olefinic oxidation products increases on moving from α-pinene to limonene and limonene to cyclohexene. Additionally. recovered heterogeneous catalysts showed intact results up to two consecutive runs. Probable catalytic mechanism has been proposed for oxidation of cyclohexene.
- Parmar, Digvijaysinh K.,Butani, Pinal M.,Thumar, Niraj J.,Jasani, Pinal M.,Padaliya, Ravi V.,Sandhiya, Paba R.,Nakum, Haresh D.,Khan, Md. Nasim,Makwana, Dipak
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- Novel access to verbenone via ruthenium nanoparticles-catalyzed oxidation of Α-pinene in neat water
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Aqueous suspensions of Ru(0) nanoparticles, stabilized with hydroxyethylammonium salts and possessing sizes around 2 nm, proved to be active and selective in the mild oxidation of α-pinene in the presence of tert-butylhydroperoxide, in neat water. Verbenone, a product of great interest for fine chemistry, was obtained as major product with yield up to 41% under optimized conditions. 2-hydroxy-3-pinanone was identified as a co-product of the reaction, but with very low amount (7%). Kinetic investigations allowed determining the potential reaction intermediates and by-products. Moreover, mechanistic studies with radical scavengers confirmed that α-pinene oxidation mainly implies both carbon- and oxygen-centered radicals.
- Rauchdi, Mariem,Ait Ali, Mustapha,Roucoux, Alain,Denicourt-Nowicki, Audrey
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p. 266 - 273
(2017/12/06)
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- Zeolite Y encaged Ru(III) and Fe(III) complexes for oxidation of styrene, cyclohexene, limonene, and α-pinene: An eye-catching impact of H2SO4 on product selectivity
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A novel Ru(III) and Fe(III) complexes of ligands 1 and/or 2 {where 1 = 2,2'-((1E,1'E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))diphenol and 2 = 2,2'-((1E,1'E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene)) bis(4-nitrophenol)} have been synthesized as ‘neat’ and zeolite Y encapsulated complexes. These catalysts are characterized by various analytical tools such as FTIR, UV–vis, elemental analysis, ICP-AES, molar conductivity, 1H- and 13C NMR, TGA, SEM, AAS, BET, magnetic susceptibility and powder XRD to endorse the complex formation, absence of peripheral redundant ligands and complexes, conservation of zeolite Y morphology and crystallinity, and the encapsulation of complexes without devastation in the zeolite Y framework. Out of these synthesized catalysts, 5Y is found to be a potent candidate for styrene (Conv. 76.1%, TOF: 2130 h?1), cyclohexene (Conv. 84.4%, TOF: 2351 h?1), limonene (Conv. 81.6%, TOF: 2273 h?1), and α-pinene (Conv. 72.6%, TOF: 2023 h?1) oxidation with high selectivity of respective allylic products excluding the styrene oxidation, which undergoes epoxidation only. The addition of H2SO4 in an identical reaction catalyzed by 5Y not only surge the conversion up to 100% in a short time span with high TOF but also increase the selectivity of respective epoxidation products. This switchover in the selectivities could be credited to the presence of H2SO4 that facilitates the heterolytic [sbnd]O[sbnd]O[sbnd] bond cleavage of metal hydroperoxide and stimulates the epoxidation over allylic oxidation. Furthermore, the results establish that the heterogeneous systems are effortlessly recovered and reused without ample drop in the activity and selectivity.
- Godhani, Dinesh R.,Nakum, Haresh D.,Parmar, Digvijaysinh K.,Mehta, Jignasu P.,Desai, Nisheeth C.
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p. 223 - 237
(2016/12/09)
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- Catalytic Activity of Crystallographically Characterized Organic–Inorganic Hybrid Containing 1,5-Di-amino-pentane Tetrachloro Manganate with Perovskite Type Structure
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Abstract: Layered 2D organic–inorganic hybrid perovskite (OIHS) of the diammonium series, 1,5 di-aminepentane tetrachloro mangenate ([NH3–(CH2)5–NH3] MnCl4) was prepared by slow evaporation and reducing temperature method and characterized by single crystal X-ray diffraction analysis. Its structure consists of organic cation, [NH3(CH2)5NH3]+2 extended in a zigzag fashion and inorganic anion, [MnCl6]?2 where Mn2+ is coordinated by six Cl? ion in octahedral fashion. The organic and inorganic segments are alternately stacked along c-axis where inorganic layer is extended through corner-shared octahedra sandwiched by the di-aminopentane molecules. The layers (organic and inorganic) were connected to each other through N–HCl hydrogen bonds and van-der Waals interaction to build cation–anion–cation cohesion. The hybrid crystal had orthorhombic non-centrosymetric system having I212121 space group with unit cell parameters a = 7.1742(3) ?, b = 7.3817(3) ?, c = 23.9650(10) ?, V = 1269.13 ?3 and Z = 4. The hybrid exhibited excellent catalytic activity towards sulphide and alkene oxidation using aqueous H2O2 as an oxidant. Graphical Abstract: OIHS of the diammonium series [NH3–(CH2)5–NH3] MnCl4; 1,5 di-aminepentane tetrachloro mangenate were prepared by slow evaporation and temperature decrease method, characterized by single crystal X-ray diffraction. This complex exhibits excellent catalytic activity towards sulphide oxidation and alkene oxidation using aqueous H2O2 as an oxidant. [Figure not available: see fulltext.].
- Mondal, Paramita,Abdel-Aal, Seham Kamal,Das, Debasis,Islam, Sk Manirul
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p. 2332 - 2339
(2017/08/22)
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- Crystallization of bisulfite derivatives of enantiomerically enriched verbenone
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After separation of crystalline bisulfite derivatives of enantiomerically enriched (1S)- and (1R)-verbenones, steam distillation of the filtrates afforded (1S)- and (1R)-verbenones whose optical purity was higher by 30 and 20%, respectively, than that of
- Kovalenko,Prat’ko,Prokhorevich
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p. 1598 - 1600
(2017/12/08)
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- Synthesis of new enantiomerically pure β-amino alcohols of the pinane series
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A series of new β-amino alcohols with pinane structure, (+)- and (?)-3α-amino-10β-pinan-4β-ols, 4β-amino-10β-pinan-3α-ol, and 4α-amino-10β-pinan-3α-ol have been synthesized with the goal of using them as organocatalysts in the aldol reaction of isatin with acetone.
- Frolova,Sudarikov,Alekseev,Banina,Slepukhin,Kutchin
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p. 335 - 343
(2017/05/09)
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- Allylic oxidation of cyclic alkenes with molecular oxygen and tert-butyl hydroperoxide over copper-manganese oxides
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Abstract: An efficient and mild method for the allylic oxidation of cyclic alkenes employing molecular oxygen and tert-butyl hydroperoxide as the oxidant, copper-manganese oxides as heterogeneous catalyst under ambient temperature is proposed. The catalyst, which was prepared by co-precipitation and characterized, was evaluated oxidation of isolongifolene as a typical mode substrate. The catalyst showed a good catalytic activity and remained nearly the same after four cycles. The scope of the reaction was investigated with a variety of cyclic alkenes compounds. Graphical abstract: [Figure not available: see fulltext.]
- Zhang, Wu,Wei, Qiuyu,Lan, Lingling,Wu, Aiqun,Yin, Xiuju,Shen, Liqun
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p. 357 - 365
(2017/02/10)
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- Optimization of reaction conditions for cyclohexane to cyclohexanone with t-butylhydroperoxide over CuCl2 loaded with activated carbon
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Catalytic oxidation of hydrocarbons can be performed efficiently in the presence of tert-butylhydroperoxide (TBHP) under a low-valent transition metal as the catalyst. CuCl2 loaded with activated carbon had synthesized and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX), and then utilized as a catalyst for the oxidation of cyclohexane with molecular oxygen as the oxidant and the TBHP as the pro-oxidant under various conditions. The possible reaction mechanism was discussed and the effects of different factors on the oxidation of cyclohexane were investigated. Reaction conditions including catalyst type, oxidant, reaction time, reaction temperature, TBHP amount, solvent type and solvent amount were systematically optimized in order to achieve the highest conversion of cyclohexane and highest selectivity of cyclohexanone. Various other alkanes exhibited higher catalytic activity under the optimal conditions.
- Sun, Xiaoling,Zhang, Xinhui,Cao, Xiaoyan,Zhao, Xiaoyan
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p. 202 - 208
(2016/02/26)
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- Zeolite-Y immobilized Metallo-ligand complexes: A novel heterogenous catalysts for selective oxidation
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Transition metal [M?=?Co(II), Cu(II)] complexes of H2L1 and H2L2 ligands have been prepared as neat and nanohybrid zeolite-Y immobilized complexes. The various analytical tools such as FTIR, ICP-AES, elemental analysis, UV–vis, Brunauer, Emmett and Teller (BET) surface area analysis, Thermal analysis, scanning electron micrographs, Powder XRD, conductivity, magnetic moment, and AAS were employed for the characterization of the prepared catalysts. Among all catalysts, the [Cu(L1)]-Y (heterogeneous) and [Cu(L1)] (homogeneous) have offered high activity and selectivity over oxidation of cyclohexene. Moreover, the [Cu(L1)] and [Cu(L1)]-Y were employed as catalyst over various organic substrates at identical reaction condition. The immobilized catalyst [Cu(L1)]-Y is found to be moderate active over oxidation of cyclohexane (75.2%,), benzene (8.21%), phenol (14.5%), styrene (87.5), benzyl alcohol (21.5%), limonene (11.2%), α-pinene (9.15%), and cyclooctane (76.8%) with high TON values (21942-2054). The mechanistic study using UV–vis and FTIR suggests the participation of active metalperoxo species, which is reinforced by its high catalytic activity over limonene (16.3%) in the absence oxidant.
- Godhani, Dinesh R.,Nakum, Haresh D.,Parmar, Digvijaysinh K.,Mehta, Jignasu P.,Desai, Nisheeth C.
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p. 105 - 116
(2016/09/07)
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- Synthesis and analgesic activity of stereoisomers of 2-(3(4)-hydroxy-4(3)-methoxyphenyl)-4,7-dimethyl-3,4,4a,5,8,8a-hexahydro-2H-chromene-4,8-diols
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2-(3(4)-Hydroxy-4(3)-methoxyphenyl)-4,7-dimethyl-3,4,4a,5,8,8a-hexahydro-2H-chromene-4,8-diols were found recently to possess high analgesic activity and low acute toxicity. Stereoisomers of these compounds with high optical purity were synthesized from (+)- and (-)-α-pinenes for the first time in this work. The structure of (4S)-4b isomer was confirmed by the XRD data. Studies of analgesic activity of the resulting products demonstrated that neither the absolute configuration nor cis- or trans-arrangement of vicinal oxygen atoms plays a significant role in manifestation of analgesic effect by these isomers, while only (4S)-4b isomer, but not (4R)-4b demonstrated the analgesic effect.
- Pavlova, Alla,Mikhalchenko, Oksana,Rogachev, Artem,Il'Ina, Irina,Korchagina, Dina,Gatilov, Yuriy,Tolstikova, Tat'Yana,Volcho, Konstantin,Salakhutdinov, Nariman
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p. 3821 - 3830
(2015/10/06)
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- Selectively catalytic epoxidation of α-pinene with dry air over the composite catalysts of Co-MOR(L) with Schiff-base ligands
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Twelve bi-/tridentate Schiff-base ligands (L1-L12) have been designed, synthesized and coordinated with ion-exchanged Co-MOR (Mordenite) forming a series of Co-MOR(L) composite catalysts, for which various analyzes and characterizations are conducted. Selectively catalytic epoxidation of α-pinene with dry air over Co-MOR(L) catalysts has been carried out, where uses TBHP in small amounts as the initiator. Among these Co-MOR(L) catalysts, Co-MOR(L8) exhibits the best activity for the titled reaction to obtain 85.8 mol% conversion and 90.8% selectivity of epoxide. Some factors such as the structure of ligands, the oxidants, the solvents, the catalyst amount, the reaction temperature and time play important roles in controlling the epoxidation. The recyclable stability of the Co-MOR(L8) catalyst is confirmed. The studies on the electrochemical behaviors of Co species in Co-MOR(L8) reveal the importance of reversible change between Co oxidation states for the epoxidation.
- Lu,Lei,Wei,Ma,Zhang,Hu,Zhou,Xia
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- Biomass toward fine chemical products: Oxidation of α-pinene over sieves nanostructured modified with vanadium
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Vanadium-containing molecular sieves (V-M(x)) were synthetized and applied as heterogeneous catalysts for the liquid phase oxidation of α-pinene with hydrogen peroxide at 70°C. It has been found that the vanadium content in V-M(x) materials affected the conversion of α-pinene and product distribution. The turnover numbers increased strongly with the decreasing of V content probably caused by a high V dispersion. The major products were verbenone, trans-sobrerol and campholenic aldehyde. The acid-base properties of V-M(x) affected the distribution of products formed via the isomerization of α-pinene oxide over Lewis acid sites to campholenic aldehyde while Br?nsted acid sites brought about the formation of 1,2 pinanediol and trans-sobrerol by hydrolysis and by the opening of oxirane ring. The increase in V content in V-M(x) led to the increase in campholenic aldehyde, 1,2 pinanediol, trans- sobrerol and over oxidation products. Moreover, the effect of several solvents on the reaction oxidation was studied. The results showed that the highest α-pinene conversions are obtained in the following order: acetonitrile > ethanol > isoamyl alcohol > methyl ethyl ketone. Thus, using aprotic solvents, the catalytic activity was increased and the formation of alkyl glycol ethers as by-product was not observed.
- Cánepa, Analía L.,Chanquía, Corina M.,Vaschetti, Virginia M.,Eimer, Griselda A.,Casuscelli, Sandra G.
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- Continuous flow photooxygenation of monoterpenes
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Photooxygenation of monoterpenes was conducted in two continuous flow reactors. The first, suitable for lab-scale research, had a maximum yield of 99.9%, and the second, focused on industrial applications, showed a daily output that was 270.0-fold higher than that in batch systems. The use of sunlight instead of an LED lamp gave 68.28% conversion.
- Park, Chan Yi,Kim, Young Joon,Lim, Hyo Jin,Park, Jeong Hyeon,Kim, Mi Jin,Seo, Seung Woo,Park, Chan Pil
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p. 4233 - 4237
(2015/02/19)
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- Monoterpene hydroxylation with an artificial self-sufficient P450 utilizing a P450SMO reductase domain for the electron transfer
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Cytochrome P450SMO from Rhodococcus sp. ECU0066 is a natural self-sufficient P450 monooxygenase, consisting of a heme domain, a flavin-reductase domain containing FMN and NADPH binding sites, and a [Fe2S2] ferredoxin domain. P450cam catalyzes the hydroxylation of camphor to 5-exo-hydroxycamphor. The variant P450cam (Y96F/V247L) was reported for the oxidation of monoterpene by protein engineering. In this work, we constructed an artificial self-sufficient P450-type monoterpene hydroxylase by connecting the P450SMO reductase domain and the P450cam (Y96F/V247L) domain together with a linker region (G4S)4. The resultant chimeric P450 enzyme could catalyze the hydroxylation of (-)-limonene and α-pinene as well as camphor, which were all inactive for the natural fusion protein P450SMO. Co-expression of the fused P450 with a glucose dehydrogenase (GDH) improved the (-)-limonene conversion as sufficient NADPH was regenerated in the system with glucose as a cosubstrate. This work illustrated that P450SMO reductase might act as an electron donor partner of P450s and might be used for fusion with heterogeneous P450 domains to elucidate the catalytic function of other unknown P450s.
- Luan, Zheng-Jiao,Yin, Yue-Cai,Li, Ai-Tao,Yu, Hui-Lei,Xu, Jian-He
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- Aerobic oxidation of α-pinene catalyzed by carbon nanotubes
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Carbon nanotubes (CNTs) and nitrogen-doped CNTs (NCNTs) as metal-free catalysts exhibited an excellent activity in the selective oxidation of α-pinene with molecular oxygen as the terminal oxidant. Two distinct pathways, i.e. epoxidation and allylic oxidation, were active in this reaction. Enhancement of epoxidation was observed over CNTs, yielding the highest epoxidation/allylic oxidation products ratio. Excellent activity was achieved over NCNTs, giving 54.5% α-pinene conversion and 272.4 mmol g-1 h-1 mass-normalized activity, which compete with that of the state-of-the-art metal catalysts. Allylic oxidation was enhanced over NCNTs, using which equimolar amounts of epoxide and allylic products were produced. Thus, N-doping boosted the overall conversion and the yields of both epoxidation and allylic oxidation products, which was supported by the results of theoretical simulation.
- Cao, Yonghai,Li, Yuhang,Yu, Hao,Peng, Feng,Wang, Hongjuan
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p. 3935 - 3944
(2015/08/03)
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- Polymer-supported diimine molybdenum carbonyl complexes as highly reusable and efficient pre-catalysts in epoxidation of alkenes
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By reaction of aldehydic polystyrene and ethylene diamine, polystyrene-imine-amine reagent was produced. Reaction of this reagent with benzaldehyde and 4-nitrobenzaldehyde resulted in polystyrene-diimines (3a and 3b). These reagents were used for the immobilization of molybdenum hexacarbonyl. The functionalized polystyrene and supported-diimine molybdenum carbonyl catalysts were characterized by FT-IR spectrum and CHN analysis. The molybdenum content of catalysts was determined by neutron activation analysis. Supported-diimine molybdenum carbonyl pre-catalysts (3aM and 3bM) were used in epoxidation of cyclooctene, and the reaction parameters such as solvent and oxidant were optimized and the epoxidation of different alkenes was investigated in optimizing these conditions. The obtained results in the presence of polymer-supported diimine molybdenum carbonyl pre-catalysts (3aM and 3bM) showed that they were very active and selective in the epoxidation of a wide range of alkenes. The reusability of the supported pre-catalysts was also studied. The results showed that they were highly reusable in epoxidation of alkenes.
- Grivani, Gholamhossein,Halili, Ali
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p. 163 - 168
(2014/01/23)
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- Hydrocarbon oxidation over Fe- and Cr-containing metal-organic frameworks MIL-100 and MIL-101-a comparative study
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Catalytic properties of Fe- and Cr-based metal-organic frameworks (MOFs) MIL-100 and MIL-101 have been assessed in two liquid-phase reactions: solvent-free allylic oxidation of alkenes (cyclohexene, α- and β-pinenes) with molecular oxygen and oxidation of anthracene (AN) with tert-butyl hydroperoxide (TBHP). In the oxidation of alkenes, the product selectivity strongly depends on the nature of metal (Fe or Cr) but, for the same metal, only slightly differs for the MIL-100 and MIL-101 structures. The Fe-containing MOFs afford the formation of unsaturated alcohols while Cr-based MOFs give mainly unsaturated ketones. Both Cr-MIL-100 and Cr-MIL-101 favor decomposition of cyclohexenyl hydroperoxide to produce 2-cyclohexen-1-one with 67-69% selectivity. Stability toward destruction reduced in the order Cr-MIL-101, Cr-MIL-100 > Fe-MIL-100 > Fe-MIL-101. In the oxidation of anthracene over both Cr-MOFs and Fe-MIL-101, the selectivity toward 9,10-anthraquinone (AQ) attained 100% at 92-100% AN conversion. The turnover frequency (TOF) decreased in the order Cr-MIL-101 > Fe-MIL-101 > Cr-MIL-100 > Fe-MIL-100. Cr-MIL-101 revealed superior catalytic performance in terms of AN conversion, AQ selectivity and TOF. Nearly quantitative yield of AQ was obtained after 1.5 h at 100 °C in chlorobenzene as solvent. No leaching of active metal occurred under optimal reaction conditions and the MOFs could be recycled several times without deterioration of the catalytic properties.
- Kholdeeva, Oxana A.,Skobelev, Igor Y.,Ivanchikova, Irina D.,Kovalenko, Konstantin A.,Fedin, Vladimir P.,Sorokin, Alexander B.
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- Epoxidation of mixed bi-olefins with air over nanosized Co 3O4 assisted by ultrasonic waves
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Nanosized Co3O4 prepared by a simple method is considerably active in the ultrasonic waves assisted epoxidation of mixed bi-olefins with dry air. Both conversions and selectivities are distinctly promoted with α-methylstyrene and α-pinene mixed in the molar ratio of 1:1, as compared to α-methylstyrene or to α-pinene alone. When other alkenes are mixed with cyclooctene at 1:5 (molar ratio), different effects are observed. The mixture of styrene and cyclooctene shows almost the same increase in activity as the mixture of α-methylstyrene and α-pinene. While isophorone could assist the epoxidation of cyclooctene, by itself it could not be oxidized by molecular oxygen under the present conditions. When indene is mixed with cyclooctene, its conversion increases; however, the reactivity of cyclooctene decreases notably. UV-vis spectral analysis shows that these observations may be due to the intermolecular electron transfer which is very important for the enhancement of reactivities of bi-olefinic molecules.
- Lei,Lu,Zhang,Wei,Zhou,Xia
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p. 709 - 716
(2013/07/27)
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- Solvent-free allylic oxidation of alkenes with O2 mediated by Fe- and Cr-MIL-101
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Catalytic properties of Fe-MIL-101 and Cr-MIL-101 metal-organic frameworks in the solvent-free oxidation of cyclohexene and α-pinene with molecular oxygen have been explored. Both catalysts allow alkene oxidation under mild conditions (1 bar O2, 40-60°C) and afford allylic oxidation products. The nature of catalysis and the product distribution strongly depend on the nature of the transition metal. Cr-MIL-101 behaves as truly heterogeneous catalyst to give predominantly α,β-unsaturated ketones. Catalysis over Fe-MIL-101 has true heterogeneous nature only at 40°C, producing mainly 2-cyclohexene-1-ol. At 50-60°C, iron leaching into solution occurs, leading to cyclohexenyl hydroperoxide as the major product. Under optimal conditions, both catalysts can be reused several times without suffering a loss of the catalytic properties. Rate-retarding and rate-accelerating effects of inhibitors and initiators, respectively, indicate radical chain mechanism. Different pathways for transformation of hydroperoxide have been suggested to rationalize the observed differences in the reaction selectivities over Cr- and Fe-MIL-101.
- Skobelev, Igor Y.,Sorokin, Alexander B.,Kovalenko, Konstantin A.,Fedin, Vladimir P.,Kholdeeva, Oxana A.
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- Vanadium-containing nickel phosphate molecular sieves as catalysts for α-pinene oxidation with molecular oxygen: A study of the effect of vanadium content on activity and selectivity
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Vanadium-containing nickel phosphate molecular sieves (V-VSB-5) were applied as heterogeneous catalysts for the liquid phase oxidation of α-pinene with molecular oxygen at 60 °C. It has been found that the vanadium content in V-VSB-5 materials affects the
- Timofeeva, M. N.,Panchenko, V. N.,Prosvirin, I. P.,Hasan, Zubair,Jhung, Sung Hwa
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p. 328 - 334,7
(2020/07/30)
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- A recyclable polymer anchored copper(II) catalyst for oxidation reaction of olefins and alcohols with tert-butylhydroperoxide in aqueous medium
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A new reusable polymer anchored Cu(II) complex was synthesized which can acts as an efficient heterogeneous catalyst for oxidation of olefins and alcohols with tert-butylhydroperoxide (TBHP) in aqueous medium. The present catalyst well oxidized styrene and other olefins to their allylic products and alcohols were converted to their corresponding aldehydes in good-to-moderate yields. This catalyst can be easily recovered by filtration and recycled without significant loss of its catalytic performances.
- Islam,Roy, Anupam Singha,Mondal, Paramita,Paul, Sumantra,Salam, Noor
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p. 170 - 176
(2012/10/30)
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- [PZnMo2W9O39]5- immobilized on ionic liquid-modified silica as a heterogeneous catalyst for epoxidation of olefins with hydrogen peroxide
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The epoxidation of alkenes with hydrogen peroxide catalyzed by [PZnMo 2W9O39]5-, ZnPOM, supported on ionic liquid-modified silica, Im-SiO2, is reported. The immobilized catalyst, [ZnPOM@Im-SiO2] was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV-Vis spectroscopic methods. This new synthesized hybrid catalyst was applied for efficient epoxidation of various olefins with aqueous H2O2 in acetonitrile under reflux conditions. This solid catalyst can be easily recovered by simple filtration and reused several times without significant loss of its catalytic activity.
- Hajian, Robabeh,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Khosropour, Ahmad Reza
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p. 975 - 979
(2013/02/22)
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- Enzymatic allylic oxidations with a lyophilisate of the edible fungus Pleurotus sapidus
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Allylic oxidations belong to the most attractive synthetic transformations because they convert readily available and cheap starting materials into value-added products. In this study, we describe oxidative conversions of terpenoids and a number of related cycloalkenes with a lyophilisate of the edible fungus Pleurotus sapidus. The biocatalytic protocol is simple and the biocatalyst is readily available. The conversions of various cycloalkenes proceed cleanly in most cases to the corresponding enones. The substrate scope is remarkable and includes a number of mono- and sequiterpenes, functionalized terpenoids as well as simple cyclohexenes and benzylic substrates. Enzymatic allylic oxidations by Pleurotus sapidus are thus an excellent non-toxic alternative to metal-mediated oxidation procedures in academic labs and for industrial application in food technology, cosmetics or pharmaceutical research. The Royal Society of Chemistry 2012.
- Rickert, Aljona,Krombach, Verena,Hamers, Oliver,Zorn, Holger,Maison, Wolfgang
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experimental part
p. 639 - 644
(2012/04/23)
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- Radical reactions on pinene-oxide derivatives induced by Ti(III)
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A practical, brief and selective synthesis of several pinene oxide derived terpenoids can be achieved from readily available starting materials. The key step is a radical reaction promoted by titanocene chloride.
- Fernández-Mateos,Herrero Teijón,Rubio González
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supporting information; experimental part
p. 9529 - 9534
(2011/12/15)
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- Cobalt(III)-oxo cubane clusters as catalysts for oxidation of organic substrates
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Transition metal coordination complexes play a vital role as catalysts in the oxidation of organic substrates including renewable chemicals in an economically viable and environmentally friendly way. Here we highlight the preparation, characterization and application of oxo-cubane complexes of cobalt(III) as oxidation catalysts using air and water as oxidants. Cobalt(III)-oxo complexes of the type Co4O4(O 2CR)4L4 have been prepared by a general method and these have been characterized by analytical, spectroscopic, electrochemical and crystallographic methods. These soluble complexes have shown promising utility as catalysts in the aerobic oxidation of side chains of alkylaromatic hydrocarbon compounds. Oxidation of neat ethylbenzene has shown very high conversion and selectivity for acetophenone formation. On the other hand, oxidation of p-xylene has been found to yield both p-toluic acid and terephthalic acid. It is also possible to oxidize p-xylene in an aqueous medium under moderate applied O2 pressure. Selective epoxidation of α-pinene with air as the oxidant also takes place with the cobalt(III)-based homogeneous catalysts. Indian Academy of Sciences.
- Das, Birinchi Kumar,Chakrabarty, Rajesh
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experimental part
p. 163 - 173
(2012/03/26)
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- Synthesis, characterization, and catalytic activity of a polymer-supported copper(II) complex with a thiosemicarbazone ligand
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A thiosemicarbazone Cu(II) complex anchored to a polystyrene framework has been synthesized and characterized by analytical and spectroscopic techniques. The complex was found to be a highly active catalyst for the oxidation of various organic substrates including alkenes and alcohols using H 2O2 as oxidant. The reaction conditions were optimized with respect to temperature, solvent, oxidant, catalyst amount, and substrate to peroxide ratio. The heterogeneous catalyst was reused five times without significant loss of activity. A comparison between the catalytic activities of this polymer-supported Cu(II) complex and its homogeneous analogue was carried out.
- Islam, Manirul,Hossain, Dildar,Mondal, Paramita,Tuhina, Kazi,Roy, Anupam Singha,Mondal, Sanchita,Mobarak, Manir
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experimental part
p. 223 - 230
(2012/04/17)
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- Highly potent activity of (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3- ene-1,2-diol in animal models of parkinson's disease
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(1R,2R,6S)-3-Methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol 1 possesses potent antiparkinsonian activity in both MPTP and haloperidol animal models. The use of compound 1 resulted in nearly full recovery of the locomotor and exploratory activities and was as effective as the comparator agent (levodopa). All eight stereoisomers of compound 1 have been synthesized and the influence of the absolute configuration on the antiparkinsonian activity of compound 1 was shown.
- Ardashov, Oleg V.,Pavlova, Alla V.,Il'ina, Irina V.,Morozova, Ekaterina A.,Korchagina, Dina V.,Karpova, Elena V.,Volcho, Konstantin P.,Tolstikova, Tat'yana G.,Salakhutdinov, Nariman F.
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supporting information; experimental part
p. 3866 - 3874
(2011/08/07)
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- Synthesis and characterization of supported heteropolymolybdate nanoparticles between silicate layers of Bentonite with enhanced catalytic activity for epoxidation of alkenes
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A new heterogeneous catalyst (PVMo/Bentonite) consisting of vanadium substituted heteropolymolybdate with Keggin-type structure Na 5[PV2Mo10O40]·14H 2O (PVMo) supported between silicate layers of bentonite has been synthesized by impregnation method and characterized using X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy and elemental analysis. X-ray diffraction and scanning electron microscopy analysis indicated that PVMo was finely dispersed into layers of bentonite as support. The PVMo/Bentonite used as an efficient heterogeneous catalyst for epoxidation of alkenes. Various cyclic and linear alkenes were oxidized into the corresponding epoxides in high yields and selectivity with 30% aqueous H2O 2. The catalyst was reused several times, without observable loss of activity and selectivity. The obtained results showed that the catalytic activity of the PVMo/Bentonite was higher than that of pure heteropolyanion (PVMo).
- Salavati, Hossein,Rasouli, Nahid
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scheme or table
p. 1853 - 1859
(2011/11/05)
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- Zirconia-supported Keggin phosphomolybdovanadate nanocomposite: A heterogeneous and reusable catalyst for alkene epoxidation under thermal and ultrasonic irradiation conditions
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Keggin phosphomolybdovanadate, PVMo, was supported on a zirconia matrix by the wet impregnation method. The phase and chemical structure, optical absorption, surface physicochemical properties and morphology of PVMo-ZrO 2 composite were studied by X-ray diffraction (XRD) technique, FT-IR and diffuse reflectance UV-vis spectroscopic (DR UV-vis) methods, and scanning electron microscopy (SEM), which indicated that the primary Keggin structure has remained intact after formation of the composite. Moreover, the obtained nanocomposite was used as an efficient catalyst of olefins under reflux and ultrasonic irradiation conditions. The catalyst was reused several times, without observable loss of activity and selectivity. Indeed, the catalytic activity of the PVMo-ZrO2 was compared with pure Keggin phosphomolybdovanadate.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 588 - 596
(2012/05/20)
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- Solvent-free chromium catalyzed aerobic oxidation of biomass-based alkenes as a route to valuable fragrance compounds
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Chromium containing mesoporous molecular sieves MCM-41 were shown to be an efficient heterogeneous catalyst for the liquid-phase aerobic oxidation of various monoterpenic alkenes under mild solvent-free conditions. The material was prepared through a direct hydrothermal method and characterized by ICP-AES, N2 adsorption-desorption, TEM, XRD, SAXS, and H2-TPR techniques. Characterizations suggest that chromium introduced in MCM-41 is essentially incorporated in the silica framework, with no extraframework chromium oxides being detected. Various oxygenated monoterpenoids important for the flavor and fragrance industry were obtained with high combined selectivities (75-92%) at 30-40% substrate conversions. The oxidation of β-pinene led almost exclusively to allylic mono-oxygenated derivatives, whereas limonene and α-pinene gave both epoxides and allylic oxidation products. The catalyst undergoes no metal leaching and can be easily recovered and re-used. A silica-included chromium catalyst prepared through a conventional sol-gel method showed activity comparable with that of Cr-MCM-41; however, selectivity was much lower.
- Robles-Dutenhefner, Patricia A.,Brand?o, Bruno B.N.S.,De Sousa, Líniker F.,Gusevskaya, Elena V.
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experimental part
p. 172 - 178
(2012/02/05)
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- Selective photosensitized oxidation and its catalytic regulation of monoterpene with molecular oxygen in different reaction media
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The photo-catalytic oxidation of α-pinene, β-pinene and limonene with molecular oxygen sensitized by tetrachlorotetraiodo-fluorescein sodium salt (RB) has been studied in different reaction media under green light irradiation. Simple and efficient photosensitized oxidation equipment was employed successfully to improve the efficiency of the photosensitized reaction. The results indicate that the photosensitized oxidation products can be directly obtained without after-treatment by reductive reagent. Furthermore, it was found that the product distributions are remarkably affected by reaction media, and that N,N-dimethylformamide (DMF) can regulate the selectivity to products. In particular, the good selectivity (85%) to the main product (myrtenal) and the excellent conversion (99%) were obtained in the absence of any other catalysts when DMF was used as reaction solvent in the photosensitized oxidation of β-pinene. Moreover, the possible photosensitized oxidation reaction mechanism in different media was suggested in the present work.
- You, Kuiyi,Yin, Dulin,Mao, Liqiu,Liu, Pingle,Luo, He'An
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experimental part
p. 321 - 325
(2011/10/13)
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- H2O2 based α-pinene oxidation over Ti-MCM-41. A kinetic study
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α-Pinene oxidation with hydrogen peroxide using Ti-MCM-41, prepared by hydrothermal synthesis, with a Ti content of 1.12 wt.% was studied. The major products of reaction observed were: verbenone, verbenol and campholenic aldehyde which are used in the pha
- Cánepa, Analía L.,Herrero, Eduardo R.,Crivello, Mónica E.,Eimer, Griselda A.,Casuscelli, Sandra G.
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experimental part
p. 1 - 7
(2011/10/09)
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- Aerobic epoxidation of olefins over the composite catalysts of Co-ZSM-5(L) with bi-/tridentate Schiff-base ligands
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Three tridentate or bidentate Schiff-base ligands inclusive of salicylaldehyde benzoylhydrazone (L1), vanillic aldehyde benzoylhydrazone (L2) and 4-methyl benzaldehyde benzoylhydrazone (L3), have been designed, synthesized and employed to coordinate with Co2+ ions and ion-exchanged Co-ZSM-5 forming several Co-L complexes and Co-ZSM-5(L) composite catalysts. The catalytic epoxidation of several alkenes with dry air has been carried out at 90 °C under atmospheric pressure using Co-L complexes and Co-ZSM-5(L) catalysts (using TBHP in small amounts as the initiator). In contrast, the catalysts Co-ZSM-5(L) shows higher catalytic activity than Co-ZSM-5 itself and Co-L complexes. Among three Co-ZSM-5(L) catalysts, Co-ZSM-5(L1) exhibits the highest activity for the selective epoxidation of alkenes. Recycling studies show the recyclability of Co-ZSM-5(L1) as a heterogeneous catalyst, which does not lose the catalytic activity after even eight reuses appreciably. Based on the experiments, one possible reaction mechanism is proposed.
- Qi,Lu,Fang,Lei,Dong,Zhou,Xia
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scheme or table
p. 44 - 51
(2011/03/17)
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- Highly efficient epoxidation of alkenes with sodium periodate catalyzed by reusable polystyrene-bound ruthenium(III) salophen
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In this paper, highly efficient epoxidation of alkenes catalyzed by ruthenium(III) salophen chloride, [Ru(salophen)Cl], supported on functionalized chloromethylated polystyrene, PS, is reported. The PS was modified with 1,4-diaminobenzene, 4-aminophenol and 4-aminothiophenol, and [Ru(salophen)Cl] was attached to the supports via axial ligation. The prepared catalysts were used for efficient epoxidation of alkenes with NaIO4 at room temperature. These new heterogenized catalysts were characterized by elemental analysis, FT-IR spectroscopy, scanning electron microscopy and transmission electron microscopy. The heterogeneous catalysts were reusable in the oxidation reactions and were reused several times.
- Moghadam,Mirkhani,Tangestaninejad,Mohammadpoor-Baltork,Kargar,Sheikhshoaei,Hatefi
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experimental part
p. 1019 - 1029
(2012/02/16)
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- Visible-light-induced metal-free allylic oxidation utilizing a coupled photocatalytic system of g-C3N4 and N-hydroxy compounds
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Graphitic carbon nitride (g-C3N4) and N-hydroxy compounds can function as a non-metal photocatalytic system to activate O 2 for the selective allylic oxidation under mild conditions, avoiding the employment of any metal derivative or organic oxidizing agents. Interestingly, the novel photocatalytic system affords a remarkably high selectivity towards the formation of aldehydes, especially in the oxidation of toluene. By combining the unique nature of g-C3N4 (surface basicity, semiconductor features, high stability) and the remarkable catalytic oxidation reactivity of nitroxyl radicals, this photocatalytic system opens up a mild and efficent access for C-H bond activation. Copyright
- Zhang, Pengfei,Wang, Yong,Yao, Jia,Wang, Congmin,Yan, Chao,Antonietti, Markus,Li, Haoran
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experimental part
p. 1447 - 1451
(2011/08/03)
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- An unprecedented method for the generation of tert -butylperoxy radical using DIB/TBHP protocol: Solvent effect and application on allylic oxidation
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Figure presented Tert-Butylperoxy radical was generated with PhI(OAc) 2 and tBuOOH. Ester solvent was found to be critical and the protocol was applied in the allylic oxidation of various olefinic substrates, which gave the corresponding α,β-unsaturated enones in good yield and regioselectivity.
- Zhao, Yi,Yeung, Ying-Yeung
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supporting information; experimental part
p. 2128 - 2131
(2010/08/05)
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- Silica supported Ru(salophen)Cl: An efficient and robust heterogeneous catalyst for epoxidation of alkenes with sodium periodate
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In the present work, heterogenization of Ru(salophen)Cl via its axial ligation to silica-bound imidazole, SiIm, is reported. The heterogeneous catalyst, [Ru(salophen)Cl-SiIm], was characterized by elemental analysis, SEM, TEM, FT-IR and diffuse reflectance UV-Vis spectroscopic techniques. The catalyst, which is not soluble in water and common organic solvents, was used for efficient epoxidation of cyclic and linear alkenes with NaIO4 under agitation with magnetic stirring. This new heterogenized catalyst is of high stability and reusability in the oxidation reactions. The effect of reaction parameters such as solvent and oxidant in the epoxidation of cis-cyclooctene were also investigated.
- Hatefi, Mehdi,Moghadam, Majid,Mirkhani, Valiollah,Sheikhshoaei, Iran
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experimental part
p. 2953 - 2958
(2011/01/07)
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- Sonocatalytic oxidation of olefins catalyzed by heteropolyanion-montmorillonite nanocomposite
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A Keggin-type heteropolyanion compound (HPO) was doped within the montmorillonite (MMT) structure by impregnation method. The synthesized catalyst was characterized by FT-IR, XRD, UV-vis, CV, SEM and elemental analysis. Based on chemical adsorption between HPO, and hydroxyl surface groups, HPOs nanoparticles were successfully located on the MMT. Moreover, the obtained nanocomposite was found as an efficient catalyst for oxidation of hydrocarbons under reflux and ultrasonic irradiation conditions.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 145 - 152
(2010/11/18)
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- Sonocatalytic epoxidation of alkenes by vanadium-containing polyphosphomolybdate immobilized on multi-wall carbon nanotubes
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A Keggin type polyoxometalate (POM) has been immobilized in the unique network structure of multi-wall carbon nanotubes (CNTs). The vanadium-containing polyphosphomolybdate (PVMo) supported on CNTs, which was prepared by a one-step solid-state reaction, was characterized by FT-IR, XRD, SEM and elemental analyses. These uniform nanoparticles have an average size 20-30 nm. Furthermore, due to the chemical interaction between PVMo and carboxylic acid groups, PVMo nanoparticles were successfully immobilized on the CNTs. Moreover, the obtained composite was found as an efficient catalyst for oxidation of hydrocarbons under reflux and ultrasonic irradiation (US) conditions.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 453 - 459
(2010/12/25)
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- Mechanism of the aerobic oxidation of α-Pinene
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A combined experimental and theoretical approach is used to study the thermal autoxidation of α-pinene. Four different types of peroxyl radicals are generated; the verbenyl peroxyl radical being the most abundant one. The peroxyl radicals propagate a long
- Neuenschwander, Ulrich,Guignard, Florian,Hermans, Ive
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experimental part
p. 75 - 84
(2011/02/21)
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- Benzylic and allylic oxidations with bis(trifluoroacetoxyiodo)benzene and tert -butyl hydroperoxide
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Oxidation of benzylic and allylic substrates with a bis(trifluoroacetoxyiodo)benzene/tert-butyl hydroperoxide system to the corresponding ,-unsaturated enones was investigated. The scope and reaction mechanism are discussed. Georg Thieme Verlag Stuttgart New York.
- Catir, Mustafa,Kilic, Hamdullah
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experimental part
p. 1319 - 1322
(2010/08/06)
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