- Catalytic epoxidation of β-pinene with aqueous hydrogen peroxide
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Epoxidation of β-pinene with 35–38% aqueous hydrogen peroxide in a new catalytic system containing manganese sulfate, salicylic acid, sodium bicarbonate and polar solvent (DMF, acetonitrile, methanol) is described. The method of quantitavive determination of β-pinene and its epoxide is developed.
- Fomenko,Bakhvalov,Kollegov,Salakhutdinov
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- Diamine-Decorated Graphene Oxide with Immobilized Gold Nanoparticles of Small Size for Alkenes Epoxidation with H2O2
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Abstract: Diamine-decorated graphene oxide (NH2-GO) is successfully synthesized by covalently intercalated ethanediamines into the flat planes and edge of the GO sheet. The diamines could be act as buffer layer, thereby avoiding the stacking of graphene sheets, and offer abundant metal-chelating sites to subsequently obtain well-dispersed metal nanoparticles of small size. After the in situ reduction and deposition of AuNPs, it was found that the Au particle size of Au0.9%@NH2-GO estimated to be around 2–5?nm. The as-prepared GO-supported small AuNPs exhibited good catalytic performance for the heterogeneous epoxidation of alkenes with H2O2 under mild conditions. Notably, they presented good expansibility for either bulky or less bulky alkenes in this reaction, owing to the facilitated efficiency of mass transfer of substrates and products resulted from the supporting effect of intercalated diamines and high surface area of GO. Moreover, these heterogeneous catalysts could be readily recovered and recycled for five times with the remained activity and selectivity. Graphic Abstract: Gold nanoparticles of small size immobilized on the diamine-decorated graphene oxide has been developed, which employed as an efficient, universal and reusable catalyst for the epoxidation of alkenes using H2O2 as an oxidant.[Figure not available: see fulltext.].
- Zheng, Weiguo,Hu, Haining,Chen, Yaju,Tan, Rong,Yin, Donghong
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- A highly efficient method of epoxidation of olefins with hydrogen peroxide catalyzed by changeable hexadentate 8-quinolinolato manganese(III) complexes
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Novel hexadentate binding 8-quinolinolato manganese(III) complexes were proposed and conveniently synthesized for the epoxidation of olefins with aqueous hydrogen peroxide in water-acetone media with ammonium acetate and acetic acid as additives. The catalytic efficiencies of the suggested catalysts were found to be obviously superior to the traditional tetradentate salen-MnIIICl, due to their special hexadentate binding structures that could be easily converted to the corresponding pentadentate with pendant hydroxyl groups by opening an axial Mn{single bond}O bond in the reaction media, as supported by UV-vis spectra, in situ cyclic voltammetry, and quartz crystal microbalance characterizations.
- Zhong, Sheng,Tan, Yueming,Fu, Zaihui,Xie, Qingji,Xie, Fang,Zhou, Xiaoping,Ye, Zhengpei,Peng, Guosheng,Yin, Dulin
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- Method for synthesizing epoxy pinane from pinene
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The invention relates to a method for synthesizing epoxy pinane from pinene. The method comprises the following steps: 1) fully mixing pinene, a solvent and an auxiliary agent; 2) dropwise adding hydrogen peroxide and acetic anhydride into the mixed solution obtained in the step 1) at a certain temperature for reaction; and 3) after the reaction is finished, washing the material, recovering the solvent under reduced pressure, and rectifying under reduced pressure to obtain the product epoxy pinane. The method provided by the invention has the advantages of high conversion rate, good selectivity, mild reaction conditions, simple operation and the like, and the method has high economic applicability and is suitable for industrial production.
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Paragraph 0036-0037
(2021/04/07)
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- A recyclable cobalt(iii)-ammonia complex catalyst for catalytic epoxidation of olefins with air as the oxidant
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[Co(NH3)6]Cl3and other ammonia complexes with different external anions or metal ions were synthesized to catalyze the epoxidation of α-pinene. The synthesized complexes were characterized using XRD, SEM, TGA, FTIR and UV spectra. With air as the oxidant, [Co(NH3)6]Cl3exhibited excellent catalytic activity for the epoxidation of α-pinene among the prepared complexes. The conversion of α-pinene reached 97.4%, with 98.3% selectivity of epoxide when using a small amount of cumene hydroperoxide (CHP) as the initiator. The results revealed that a single Co(iii) system can also catalyze the epoxidation process in the absence of Co(ii), even showing better catalytic performance than single Co(ii). Recycling experiments showed that there was no significant drop in activity after 10 cycles, demonstrating that it is a stable and efficient heterogeneous catalyst for the epoxidation of α-pinene. The excellent recycling performance may be attributed to the stability of the coordination complex itself.
- Wang, Chenlong,Zhan, Hongju,Lu, Xinhuan,Jing, Run,Zhang, Haifu,Yang, Lu,Li, Xixi,Yue, Fanfan,Zhou, Dan,Xia, Qinghua
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p. 2147 - 2156
(2021/02/06)
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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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- Easy Epoxidation of Monoterpenes from Common Starting Materials
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Epoxidation of monoterpenes, α-pinene, β-pinene, limonene, α-terpinene, and (R)-carvone was carried out by the in situ production of a peroxyacid rather than direct addition of such an expensive and difficult to handle chemical. Previous reports showed use of metal catalysts with high yields, while methodologies without catalysts at high temperature showed yields lower than 30%. The authors report a methodology that produces peroxyacetic acid in situ yielding up to 75% pure epoxide at room temperature avoiding the use of catalysts. The products were analyzed by gas chromatography mass spectrometry (GC-MS), and structures were characterized by 1H and 13C nuclear magnetic resonance (NMR).
- Benitez, Ricardo B.,Bermudez, John H.,Franco, Jaime M.,Rojas, Giovanni
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p. 1086 - 1092
(2020/10/14)
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- Fast-synthesis and catalytic property of heterogeneous Co-MOF catalysts for the epoxidation of α-pinene with air
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In the past decades, many methods have been developed for synthesizing MOFs, including solvothermal synthesis, mechanical synthesis, electrochemical synthesis, and microwave synthesis. Based on the existing research, a method is proposed for synthesizing Co-MOF by rapidly rotating hydrothermal crystallization, which largely shortens the crystallization time of Co-MOF. When the rotation speed was 150 rpm, only 2 h of crystallization time was needed to synthesize Co-MOF-150-2 with high crystallinity and stability. The optimal Co-MOF-150-2 manifested remarkable activity and selectivity for the epoxidation of α-pinene under mild conditions. The catalytic conversion of α-pinene reached the highest over the Co-MOF-150-2 catalyst, in which the conversion of α-pinene was 99.5% and the yield of 2,3-epoxypinane was 95.7%. The Co-MOF materials synthesized by the rotary method also had excellent stability and highly catalytic activity in recycling experiments. This journal is
- Zhang, Haifu,He, Jie,Lu, Xinhuan,Yang, Lu,Wang, Chenlong,Yue, Fanfan,Zhou, Dan,Xia, Qinghua
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p. 17413 - 17421
(2020/11/02)
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- Cobalt imine–pyridine–carbonyl complex functionalized metal–organic frameworks as catalysts for alkene epoxidation
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Aerobic epoxidation of alkene is a green and economical route to produce epoxides. For such reaction, transition metal complexes exhibit favorable catalytic activity. In this work, NH2-MIL-101, a stable metal–organic framework (MOF) material with large surface area and high pore volume, was functionalized with pyridine-2,6-dicarbaldehyde and Co(NO3)2, to realize the immobilization of Co(II) via imine–pyridine–carbonyl (N,N,O) tridentate ligands bonding to MOF skeleton. The modified materials were applied as heterogeneous catalysts for the aerobic epoxidation of cyclohexene at ambient temperature, and multiple factors were studied to explore their influences on catalytic effects. Under the optimal reaction conditions, satisfactory substrate conversion and epoxide selectivity were reached. In addition, this catalytic system is suitable for a variety of alkene substrates. Furthermore, recycle experiments and infrared spectroscopy characterization illustrated that the coordination surroundings of Co are altering smoothly during the reaction process, thus having?an impact on the performance of catalyst.
- Qin, Yutian,Wang, Bowei,Li, Jiayi,Wu, Xingchun,Chen, Ligong
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p. 595 - 602
(2019/05/04)
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- Kinetics of the Aqueous Phase Reactions of Atmospherically Relevant Monoterpene Epoxides
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Laboratory and field measurements have demonstrated that an isoprene-derived epoxide intermediate (IEPOX) is the origin of a wide range of chemical species found in ambient secondary organic aerosol (SOA). In order to explore the potential relevance of a similar mechanism for the formation of monoterpene-derived SOA, nuclear magnetic resonance techniques were used to study kinetics and reaction products of the aqueous-phase reactions of several monoterpene epoxides: β-pinene oxide, limonene oxide, and limonene dioxide. The present results, combined with a previous study of α-pinene oxide, indicate that all of these epoxides will react more quickly than IEPOX with aqueous atmospheric particles, even under low-acidity conditions. As for α-pinene oxide, the observed products can be mainly rationalized with a hydrolysis mechanism, and no long-lived organosulfate or nitrate species nor species that retain the β-pinene bicyclic carbon backbone are observed. As bicyclic ring-retaining organosulfate and nitrate species have been previously observed in monoterpene-derived SOA, it appears that monoterpene-derived epoxides may not be as versatile as IEPOX in producing a range of SOA species, and other mechanisms are needed to rationalize organosulfate and nitrate formation.
- Cortés, DIego A.,Elrod, Matthew J.
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p. 9297 - 9305
(2017/12/18)
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- Beta-pinene selective hydroxylation oxidation method and product thereof
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The invention discloses a beta-pinene selective hydroxylation oxidation method and a product thereof. The beta-pinene selective hydroxylation oxidation method uses ordinary-pressure oxygen or oxygen-enriched air as an oxidant, uses metal porphyrin or their solid carriers as a catalyst and is performed in the absence of an additional solvent or a co-oxidation reducer, and the beta-pinene hydroxylation oxidation product is obtained by means of the method in a high-selectivity mode. Main oxidation products include pinocarveol, 2,10-epoxy pinane and myrtenol, wherein the overall selectivity of the hydroxylation oxidation products 1 and 3 is above 90%. The usage amount of the catalyst used in method is small, a reaction process is simple, the temperature is low, the initiation rate is high, the selectivity is good, homogeneous catalysis can be achieved, and heterogeneous catalysis can also be performed after immobilization.
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Paragraph 0032; 033; 0334;
(2016/10/10)
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- Eco-friendly solvents and amphiphilic catalytic polyoxometalate nanoparticles: A winning combination for olefin epoxidation
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Eighteen eco-friendly solvents were examined to carry out the epoxidation of olefins with the amphiphilic catalytic dodecyltrimethylammonium polyoxometalate nanoparticles [C12]3[PW12O 40] in comparison with [H]3[PW12O40] and [Na]3[PW12O40]. Surprisingly, the screening of solvents with cyclooctene has revealed that the [C 12]3[PW12O40] catalyst is much more active with initial turn-over frequencies, TOF0, increasing up to a factor of 10. Moreover, the reaction occurs at competitive rates in four relevant solvents, i.e. cyclopentyl methyl ether, 2-methyl tetrahydrofuran, methyl acetate and glycerol triacetate, for which TOF0 values are higher than 260 h-1. The recyclability of the systems is demonstrated and the scope of substrates has been successfully extended to cyclohexene, 1-octene, limonene, 3-carene, α-pinene, β-pinene and neryl acetate with good epoxide selectivity. The catalytic performances in the "green" solvent are assigned to the formation of stable [C 12]3[PW12O40] nanoparticle dispersions which have been characterized by transmission electron microscopy and dynamic and multiple light scattering experiments. Finally, the Kamlet-Taft parameters were measured in order to correlate the physicochemical properties of the solvents and the catalytic activity.
- Mouret, Adrien,Leclercq, Loic,Muehlbauer, Andrea,Nardello-Rataj, Veronique
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p. 269 - 278
(2014/01/06)
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- Synthesis of a reusable polymer anchored cobalt(II) complex for the aerobic oxidation of alkyl aromatics and unsaturated organic compounds
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Polymer anchored cobalt(II) catalyst was synthesized and characterized. The solid catalyst was characterized by fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The catalytic activity of the complex was investigated for the oxidative functionalization of alkyl aromatics to benzylic ketones using O2 (1 atm) with 1 mmol H2O2. The oxidation of organic compounds with carbon-carbon double bond with molecular oxygen under atmospheric pressure in the presence of this catalyst has also been studied. Oxidation of alkenes, cycloalkenes and terpenes gave corresponding epoxy derivatives. The developed catalyst can be facilely recovered and reused six times without significant decrease in its activity and selectivity.
- Islam, Sk Manirul,Ghosh, Kajari,Molla, Rostam Ali,Roy, Anupam Singha,Salam, Noor,Iqubal, Md Asif
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- Efficient epoxidation of olefins by H2O2 catalyzed by iron "helmet" phthalocyanines
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High yields of epoxides were obtained in the oxidation of a large range of olefins using 1.2-2 equiv. of H2O2 in the presence of iron helmet phthalocyanines. The involvement of high-valent iron oxo species was evidenced using cryospray mass spectrometry.
- Skobelev, Igor Y.,Kudrik, Evgeny V.,Zalomaeva, Olga V.,Albrieux, Florian,Afanasiev, Pavel,Kholdeeva, Oxana A.,Sorokin, Alexander B.
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p. 5577 - 5579
(2013/07/25)
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- Selective oxidation of alkenes using [bmim]5[PW 11ZnO39]·3H2O hybrid catalyst
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The catalytic activity of [bmim]5[PW11ZnO 39]·3H2O as a hybrid catalyst was studied in the oxidation of various alkenes in acetonitrile, using hydrogen peroxide as oxygen source. The effect of reaction parameters such as type of solvent and oxidant, amount of catalyst and oxidant, and temperature was also investigated. From our results, [bmim]5[PW11ZnO39]·3H 2O hybrid catalyst gave higher yields and selectivity in the oxidation of alkenes and was reused four times without loss of its catalytic activity.
- Nadealian, Zahra,Mirkhani, Valliolah,Yadollahi, Bahram,Moghadam, Majid,Tangestaninejad, Shahram,Mohammadpoor-Baltork, Iraj
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p. 777 - 782
(2013/07/27)
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- β-pinene oxidation by hydrogen peroxide catalyzed by modified niobium-MCM
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Although solid niobium has a high surface area, its high Lewis and Br?nsted acidity is a drawback that always compromises its catalytic performance in oxidation reactions. In this work, treating the niobium catalyst with hydrogen peroxide circumvents this disadvantage and results in a significant increase in the selectivity of the oxidation of β-pinene. In addition, the efficiency of the niobium catalysts supported on MCM was investigated. Nb-MCM//H2O2 and Nb-MCM were the most active catalysts. Good selectivity of up to 85% at a 93-97% substrate conversion has been achieved. The catalyst can easily be recovered and reused several times without loss in activity.
- Coelho, Jakelyne V.,Oliveira, Luiz C.A.,Moura, Flavia C.C.,De Souza, Patterson P.,Silva, Cesar Augusto,Batista, Kenia Barros,Silva, Márcio José Da
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experimental part
p. 215 - 220
(2012/06/29)
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- Organocatalyzed epoxidation of alkenes in continuous flow using a multi-jet oscillating disk reactor
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The times are changing: A batch process, the Minisci epoxidation, is transformed into a continuous-flow protocol for the selective aerobic radical epoxidation of alkenes. The use of a novel reactor type allows to considerably shorten reactor residence times. Experimental results suggest that two different reaction mechanisms exist for the oxidation: one for the batch conditions and a different one for flow synthesis protocol. Copyright
- Spaccini, Raffaele,Liguori, Lucia,Punta, Carlo,Bj?rsvik, Hans-René
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scheme or table
p. 261 - 265
(2012/05/05)
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- METHOD FOR MANUFACTURING AN EPOXY COMPOUND AND METHOD FOR EPOXIDIZING A CARBON-CARBON DOUBLE BOND
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The present invention provides a method for producing an epoxy compound, comprising oxidizing a carbon-carbon double bond of an organic compound by hydrogen peroxide in the presence of a neutral inorganic salt and a mixed catalyst of a tungsten compound (a), at least one phosphorus compound selected from the group consisting of phosphoric acids, phosphonic acids, and salts thereof (b) and a surfactant (c), and an epoxidizing method comprising oxidizing a carbon-carbon double bond by hydrogen peroxide in the presence of the catalyst and the neutral inorganic salt.
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Page/Page column 12; 13
(2012/05/07)
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- Bis(pyridylimino)isoindolato-iridium complexes as epoxidation catalysts for alkenes
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The reaction of the sodium salts of ligands 1a,b (1a = 1,3-bis(2-(5-(3,5- xylyl)pyridyl)imino)-5,6-dimethylisoindole, 1b = 1,3-bis(2-(4-tert-butylpyridyl) imino)-5,6-dimethylisoindole) with [Ir(μ-Cl)(COD)]2 (COD = cyclooctadiene) and [Ir(μ-Cl)(C2H4)2] 2 afforded the corresponding isoindolato complexes [{BPI(1a,b)}IrI(COD)] (2a,b) and [{BPI(1a,b)}IrI(C 2H4)2] (3a,b), respectively. The catalytic activity of the complexes 2a,b was tested in the epoxidation of a wide range of non-electron-rich olefins, using PPO (PPO = 3-phenyl-2-(phenylsulfonyl)-1,2- oxaziridine) as oxidizing agent, giving the corresponding epoxides in moderate to high yields.
- Camerano, Jose A.,Saemann, Christoph,Wadepohl, Hubert,Gade, Lutz H.
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scheme or table
p. 379 - 382
(2011/03/21)
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- Iron-catalyzed epoxidation of aromatic olefins and 1,3-dienes
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The combination of iron(III) chloride, pyridine-2,6-dicarboxylic acid and formamidine ligands allows for the epoxidation of styrenes and conjugated dienes in excellent chemoselectivity and yields.
- Schroeder, Kristin,Enthaler, Stephan,Join, Benoit,Junge, Kathrin,Beller, Matthias
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scheme or table
p. 1771 - 1778
(2010/09/11)
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- Design of a bio-inspired imidazole-based iron catalyst for epoxidation of olefins: Mechanistic insights
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A novel defined iron catalyst for the epoxidation of aromatic and aliphatic olefins with hydrogen peroxide as the terminal oxidant is described. Our catalyst approach is based on bio-inspired both alkyl- and aryl-substituted imidazoles in combination with cheap and abundant iron trichloride hexahydrate. Heterocycles similar to imidazole can be used as ligands in this epoxidation system, too. The novel system is stable towards air and water. It is shown that the mechanism depends strongly on the used ligands and substrates. In the presence of radical scavengers no carbon-centered radical could be detected.
- Schr?der, Kristin,Junge, Kathrin,Spannenberg, Anke,Beller, Matthias
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experimental part
p. 364 - 370
(2011/01/04)
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- Novel polyaniline supported cobalt catalyzed aerobic oxidation of unsaturated organic compounds
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The oxidation of organic compounds with carbon-carbon double bond with molecular oxygen under atmospheric pressure in the presence of new polyaniline supported catalyst 1 has been studied. This catalyst turned out to be efficient and selective for oxidation of some unsaturated organic compounds. Oxidation of alkenes, cycloalkenes and terpenes give corresponding epoxy derivatives, whereas organic compounds with carbon carbon double bond in benzylic position give ketones as a main product. Taylor & Francis Group, LLC.
- Pielichowski, Jan,Kowalski, Grzegorz
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experimental part
p. 105 - 111
(2011/08/03)
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- An effective procedure for the synthesis of acid-sensitive epoxides: Use of 1-methylimidazole as the additive on methyltrioxorhenium-catalyzed epoxidation of alkenes with hydrogen peroxide
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An effective method for suppression of ring opening and rearrangement of acid-sensitive epoxides during methyltrioxorhenium(MTO)-catalyzed epoxidation of alkenes with H2O2 by using 1-methylimidazole as a co-additive has been found. The combined use of 3-methylpyrazole and 1-methylimidazole as the additives has been found to be an effective procedure that affords excellent yields of acid-sensitive epoxides for MTO-catalyzed epoxidation.
- Yamazaki, Shigekazu
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experimental part
p. 2377 - 2385
(2010/07/06)
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- Hydrogen-peroxide epoxidation of natural olefins catalyzed by a dinuclear manganese complex
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The complex of Mn(IV) with the macrocyclic N-containing ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (L) [L2Mn2O 3](PF6)2 catalyzes epoxidation of (+)-limonene in CH3CN solution at room temperature. Adding CH3COOH accelerates the reaction. The products are isomers of limonene epoxide with predominance of that with an epoxified ring double bond. Epoxidation of α- and β-pinene by this system is less effective, apparently due to extensive steric shielding of the double bonds in the pinenes.
- Mandelli,Voitiski,Schuchardt,Shul'pin
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p. 243 - 245
(2007/10/03)
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- Chemoenzymatic epoxidation of alkenes by dimethyl carbonate and hydrogen peroxide
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(matrix presented) Monoperoxy carbonic acid methyl ester can be generated under neutral conditions by lipase-catalyzed perhydrolysis of dimethyl carbonate with hydrogen peroxide. It can be used in situ for the selective and efficient epoxidation of olefins; the unstable coproduct carbonic acid monomethylester decomposes to carbon dioxide and methanol. Thus, an "acid-free" Prileshajev epoxidation is realized, which is especially useful for the epoxidation of acid-sensitive substrates such as β-pinene.
- Rusch Gen Klaas, Mark,Warwel, Siegfried
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p. 1025 - 1026
(2008/02/09)
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- Method of preparing perillyl alcohol and perillyl acetate
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A process for preparing perillyl alcohol by converting beta-pinene oxide into an alcohol in an acidic reaction medium, esterifying said alcohol to produce a mixture containing perillyl acetate, and hydrolyzing said perillyl acetate to perillyl alcohol.
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- Carbodiimide-Promoted Olefin Epoxidation with Aqueous Hydrogen Peroxide
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Commercially available carbodiimides in hydroxylic solvents containing hydrogen peroxide with mildly basic or acidic catalysts have been found to promote the epoxidation of olefins. A commercially available 30% aqueous solution of hydrogen peroxide serves as the oxidant for this process. The presumed reactive species is a peroxyisourea generated in situ by the addition of hydrogen peroxide to the carbodiimide.
- Majetich, George,Hicks, Rodgers,Sun, Guang-Ri,McGill, Patrick
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p. 2564 - 2573
(2007/10/03)
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- Mechanistic studies on the epoxidation of alkenes with molecular oxygen and aldehydes catalysed by transition metal-β-diketonate complexes
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The scope, mechanism and kinetics of the aerobic epoxidation of alkenes with an aldehyde and substituted β-diketonate-transition metal complexes as catalysts were studied. β-Diketonate complexes of nickel(II) proved to be among the best catalysts for this reaction. The epoxidation is not dependent on substrate concentration and is first order in aldehyde, catalyst concentration and oxygen partial pressure. It was shown by reactivity studies and EPR experiments that the reaction is radical in nature. Additional evidence for this was obtained from stereochemical investigations. The metal catalyst is not only an efficient initiator of the reaction, but is also believed to enhance the reactivity of intermediate species in the oxidation process by allowing these to co-ordinate to the metal center. A mechanism is proposed for the catalytic reaction.
- Wentzel, Bastienne B.,Gosling, Patricia A.,Feiters, Martin C.,Nolte, Roeland J. M.
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p. 2241 - 2246
(2007/10/03)
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- 5-Hydroperoxycarbonylphthalimide: A new reagent for epoxidation
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Peroxycarboxylic acids, widely used for epoxidation in industry and general research, have various drawbacks, such as difficulty of preparation in a pure state, cost and the possibly ring-opening of the product epoxides due to acid-catalysed reactions; a new reagent, 5-hydroperoxycarbonylphthalimide, overcomes these problems.
- James, Alun P.,Johnstone, Robert A.W.,McCarron, Moya,Sankey, J. Phillip,Trenbirth, Brian
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p. 429 - 430
(2007/10/03)
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- Polyaniline supported cobalt(II) catalyst: Oxidation of alkenes with molecular oxygen
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Polyaniline supported Co(II) acetate catalyses the oxidation of different alkenes in the presence of 2-methylpropanol under the oxygen atmosphere at ambient temperature. This catalyst can be reused for epoxidations without any decline in its catalytic efficiency.
- Das, Bhaskar C,Iqbal, Javed
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p. 1235 - 1238
(2007/10/03)
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- Kinetics and mechanism of the epoxidation of alkyl-substituted alkenes by hydrogen peroxide, catalyzed by methylrhenium trioxide
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Epoxidations of alkyl-substituted alkenes, with hydrogen peroxide as the oxygen source, are catalyzed by CH3ReO3 (MTO). The kinetics of 28 such reactions were studied in 1:1 CH3CN-H2O at pH 1 and in methanol. To accommodate the different requirements of these reactions, 1H-NMR, spectrophotometric, and thermometric techniques were used to acquire kinetic data. High concentrations of hydrogen peroxide were used, so that diperoxorhenium complex CH3Re(O)(η2-O2)2(H 2O), B, was the only predominant and reactive form of the catalyst. The reactions between B and the alkenes are about 1 order of magnitude more rapid in the semiaqueous solvent than in methanol. The various trends in reactivity are medium-independent. The rate constants for B with the aliphatic alkenes correlate closely with the number of alkyl groups on the olefinic carbons. The reactions become markedly slower when electron-attracting groups, such as halo, hydroxy, cyano, and carbonyl, are present. The rate constants for catalytic epoxidations with B and those reported for the stoichiometric reactions of dimethyldioxirane show very similar trends in reactivity. These findings suggest a concerted mechanism in which the electron-rich double bond of the alkene attacks a peroxidic oxygen of B. These data, combined with those reported for the epoxidation of styrene (a term intended to include related molecules with ring and/or aliphatic substituents) by B and by the monoperoxo derivative of MTO, suggest that all of the rhenium-catalyzed epoxidations occur by a common mechanism. The geometry of the system at the transition state can be inferred from these data, which suggest a spiro arrangement.
- Al-Ajlouni, Ahmad M.,Espenson, James H.
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p. 3969 - 3976
(2007/10/03)
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- Cobalt catalyzed oxidation of cyclic alkenes with molecular oxygen: Allylic oxidation versus double bond attack
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Cobalt (II) Schiff's base complex 1 and 2 exhibit a remarkable chemoselectivity during oxidation of cyclic alkenes with molecular oxygen in the presence of 2-methylpropanal. Catalyst 1 encourages the oxidation of double bond to give epoxide as the major product whereas catalyst 2 promotes mainly the allylic oxidation leading to allylic alcohols or enones.
- Madhava Reddy,Punniyamurthy,Iqbal, Javed
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p. 159 - 162
(2007/10/02)
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- Enantioselective synthesis of chiral liquid crystalline compounds from monoterpenes
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Chiral liquid crystalline compounds 1-9 have been synthesized enantioselectively from monoterpenes. The optical purities of (S)-(-)- and (R)-(+)-perillalcohol (16, 27), (S)-(-)- and (R)-(+)-1-pentyl-4-hydroxymethyl-1-cyclohexene (33, 34) and (2S,5S)-2-pentyl-5-hydroxymethyl-1-cyclohexanone (53) have been determined by 1H NMR analysis using chiral shift reagents. The mesomorphic phases and transition temperatures of compounds 2,3,5,6,7,8 and 9 have been characterized.
- Wang, Qian,Fan, Shi Yan,Wong, Henry N. C.,Li, Zhong,Fung, Bing M.,Twieg, Robert J.,Nguyen, Huu Tinh
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p. 619 - 638
(2007/10/02)
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- Synthesis and X-ray structure of a novel cavity-containing dinuclear nickel(II) complex
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Compounds consisting of a substrate-binding site and a NiII or MnIII salen moiety have been synthesized.These compounds are able to epoxidise a variety of alkenes in the presence of sodium hypochlorite or iodosylbenzene.The X-ray structure of the nickel(II) complex is reported.
- Gosling, P. A.,Sijbesma, R. P.,Spek, A. L.,Nolte, R. J. M.
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p. 404 - 406
(2007/10/02)
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- SODIUM PERBORATE OXIDATIONS OF CYCLIC AND ACYCLIC ALKENES TO OXIRANES OR VICINAL ACETOXY ALCOHOLS
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Under different reaction conditions, sodium perborate/acetic anhydride oxidizes alkenes into oxiranes or vicinal acetoxy alcohols in good yields.
- Xie, Gaoyang,Xu, Linxiao,Hu, Jun,Ma, Shiming,Hou, Wei,Tao, Fenggang
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p. 2967 - 2968
(2007/10/02)
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- Cyclobutane Ring Opening of Pin-2(10)-ene with Mercury(II) Salts. A New, High-yield Synthesis of p-Mentha-1,8-dien-7-ol
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The nucleophilic attack of pin-2(10)-ene-mercury(II) complex systems by water results in the opening of the four-membered ring leading to an allylic organomercury(II) derivative (11) with the p-menthane skeleton.This intermediate can be reduced by hydride to p-menth-1(2)-en-8-ol (6a) or can undergo an in situ SE2' elimination yielding p-menth-1(7)-en-8-ol (9a), in high yields. (-)-2,10-Epoxypinane (15) reacts with mercury(II) salts at room temperature, giving the diol (16) in a quantitative yield.Compound (16) is a suitable intermediate for convenient preparation of p-mentha-1,8-dien-7-ol (17) and its derivatives.
- Bluthe, Norbert,Ecoto, Jules,Fetizon, Marcel,Lazare, Sylvain
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p. 1747 - 1751
(2007/10/02)
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