- g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
-
g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
- Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
-
p. 2292 - 2298
(2021/04/12)
-
- Rare earth Ce- and Nd-doped spinel nickel ferrites as effective heterogeneous catalysts in the (ep)oxidation of alkenes
-
Cerium (Ce)- and neodymium (Nd)-doped spinel nickel ferrites catalysts system were synthesized using a cost-effective sol–gel route. The as-prepared nickel ferrites and its doped Ce and Nd nanomaterials were characterized in terms of Fourier transform infrared spectrophotometry, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, selected area diffraction pattern, zeta potential and magnetism techniques. Their catalytic potential was examined in the (ep)oxidation of 1,2-cyclooctene by using hydrogen peroxide (H2O2) or tert-butylhydroperoxide (t-BuOOH). Optimization of various parameters, including solvent, oxidant and catalyst type revealed that chloroform (CHCl3) or 1,2-dichloroethane as a solvent and t-BuOOH as an oxidant were found to be the best choice for this catalytic system. The catalytic efficiency was found as Nd–NiFe2O4 > Ce–NiFe2O4 > NiFe2O4. Further, the applied nanocatalysts could be easily renovated and exhibited high catalytic reactivity for 5 times of recycling experiments with long-time durability. A reasonable discussion of the mechanism reaction reinforced the action of these spinel catalysts.
- Adam, Mohamed Shaker S.,Hafez, Aly M.,Khalaf, Mai M.
-
p. 3237 - 3250
(2020/07/09)
-
- Polymer-anchored mononuclear and binuclear CuII Schiff-base complexes: Impact of heterogenization on liquid phase catalytic oxidation of a series of alkenes
-
Liquid phase catalytic oxidation of a number of alkenes, for example, cyclohexene, cis-cyclooctene, styrene, 1-methyl cyclohexene and 1-hexene, was performed using polymer-anchored copper (II) complexes PS-[Cu (sal-sch)Cl] (5), PS-[Cu (sal-tch)Cl] (6), PS-[CH2{Cu (sal-sch)Cl}2] (7) and PS-[CH2{Cu (sal-tch)Cl}2] (8). Neat complexes [Cu (sal-sch)Cl] (1), [Cu (sal-tch)Cl] (2), [CH2{Cu (sal-sch)Cl}2] (3) and [CH2{Cu (sal-tch)Cl}2] (4) were isolated by reacting CuCl2·2H2O with [Hsal-sch] (I), [Hsal-tch] (II), [H2bissal-sch] (III) and [H2bissal-tch] (IV), respectively, in refluxing methanol. Complexes 1–4 have been covalently anchored in Merrifield resin through the amine nitrogen of the semicarbazide or thiosemicarbazide moiety. A number of analytical, spectroscopic and thermal techniques, such as CHNS analysis, Fourier transform-infrared, UV–Vis, PMR, 13C-NMR, electron paramagnetic resonance, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetric analysis, atomic force microscopy, atomic absorption spectroscopy, and electrospray ionization-mass spectrometry, were used to analyze and establish the molecular structure of the ligands (I)–(IV) and complexes (1)–(8) in solid state as well as in solution state. Grafted complexes 5–8 were employed as active catalysts for the oxidation of a series of alkenes in the presence of hydrogen peroxide. Copper hydroperoxo species ([CuIII (sal-sch)-O-O-H]), which is believed to be the active intermediate, generated during the catalytic oxidation of alkenes, are identified. It was found that supported catalysts are very economical, green and efficient in contrast to their neat complexes as well as most of the recently reported heterogeneous catalysts.
- Maurya, Abhishek,Kesharwani, Neha,Kachhap, Payal,Mishra, Vivek Kumar,Chaudhary, Nikita,Haldar, Chanchal
-
-
- Ag3PW12O40/C3N4 nanocomposites as an efficient photocatalyst for hydrocarbon selective oxidation
-
Ag3PW12O40/C3N4 nanocomposites were successfully synthesized by loading Ag3PW12O40 into C3N4, in which case Ag3PW12O40
- Zhang, Yalin,Hu, Lulu,Zhao, Shunyan,Liu, Naiyun,Bai, Liang,Liu, Juan,Huang, Hui,Liu, Yang,Kang, Zhenhui
-
p. 60394 - 60399
(2016/07/07)
-
- Boronic acid-catalyzed selective oxidation of 1,2-diols to α-hydroxy ketones in water
-
The activation of 1,2-diols through formation of boronate esters was found to enhance the selective oxidation of 1,2-diols to their corresponding α-hydroxy ketones in aqueous medium. The oxidation step was accomplished using dibromoisocyanuric acid (DBI) as a terminal chemical oxidant or an electrochemical process. The electrochemical process was based on the use of platinum electrodes, methylboronic acid [MeB(OH)2] as a catalyst and bromide ion as a mediator. Electro-generated OH- ions (EGB) at the cathode acted as a base and "Br+" ion generated at the anode acted as an oxidant. Various cyclic and acyclic 1,2-diols as substrates were selectively oxidized to the corresponding α-hydroxy ketones via their boronate esters by the two oxidative methods in good to excellent yields.
- William, Julius M.,Kuriyama, Masami,Onomura, Osamu
-
supporting information
p. 934 - 940
(2014/04/03)
-
- Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide
-
A family of iron complexes with general formula [Fe(II)( R,Y,XPyTACN)(CF3SO3)2], where R,Y,XPyTACN=1-[2′-(4-Y-6-X-pyridyl)methyl]-4,7-dialkyl-1,4, 7-triazacyclononane, X and Y refer to the groups at positions 4 and 6 of the pyridine, respectively, and R refers to the alkyl substitution at N-4 and N-7 of the triazacyclononane ring, are shown to be catalysts for efficient and selective alkene oxidation (epoxidation and cis-dihydroxylation) employing hydrogen peroxide as oxidant. Complex [Fe(II)(Me,Me,HPyTACN)(CF 3SO3)2] (7), was identified as the most efficient and selective cis-dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and under conditions where the olefin is not used in large amounts but instead is the limiting reagent. In the presence of 3 mol% of 7, 2 equiv. of H2O2 as oxidant and 15 equiv. of water, in acetonitrile solution, alkenes are cis-dihydroxylated reaching yields that might be interesting for synthetic purposes. Competition experiments show that 7 exhibits preferential selectivity towards the oxidation of cis olefins over the trans analogues, and also affords better yields and high [syn-diol]/[epoxide] ratios when cis olefins are oxidized. For aliphatic substrates, reaction yields attained with the present system compare favourably with state of the art Fe-catalyzed cis-dihydroxylation systems, and it can be regarded as an attractive complement to the iron and manganese systems described recently and which show optimum activity against electron-deficient and aromatic olefins. Copyright
- Prat, Irene,Font, David,Company, Anna,Junge, Kathrin,Ribas, Xavi,Beller, Matthias,Costas, Miquel
-
supporting information
p. 947 - 956
(2013/05/08)
-
- Synthesis of carbon quantum dots/SiO2 porous nanocomposites and their catalytic ability for photo-enhanced hydrocarbon selective oxidation
-
We report a facile hydrolytic process for the preparation of CQDs/SiO 2 porous nanocomposites, which show high catalytic activity and stability for the selective oxidation of cis-cyclooctene under visible light irradiation, with TBHP as a radical initiator and oxygen (in the air) as an oxidant at 80 °C.
- Han, Xiao,Han, Yuzhi,Huang, Hui,Zhang, Hengchao,Zhang, Xing,Liu, Ruihua,Liu, Yang,Kang, Zhenhui
-
supporting information
p. 10380 - 10383
(2013/07/26)
-
- A hierarchically ordered porous novel vanado-silicate catalyst for highly efficient oxidation of bulky organic molecules
-
A novel hierarchically ordered porous vanado-silicate nanocomposite with interconnecting macroporous windows and meso-microporous walls containing well dispersed vanadyl species has been fabricated and used as a heterogeneous catalyst for the oxidation of a bulky organic molecule, namely cyclooctene.
- Sen, Tapas,Whittle, Jacob,Howard, Matthew
-
supporting information; experimental part
p. 4232 - 4234
(2012/05/19)
-
- Cis-dihydroxylation of alkenes with oxone catalyzed by iron complexes of a macrocyclic tetraaza ligand and reaction mechanism by ESI-MS spectrometry and DFT calculations
-
[FeIII(L-N4Me2)Cl2]+ (1, L-N4Me2 = N,N′-dimethyl-2,11-diaza[3.3](2,6) pyridinophane) is an active catalyst for cis-dihydroxylation of various types of alkenes with oxone at room temperature using limiting amounts of alkene substrates. In the presence of 0.7 or 3.5 mol % of 1, reactions of electron-rich alkenes, including cyclooctene, styrenes, and linear alkenes, with oxone (2 equiv) for 5 min resulted in up to >99% substrate conversion and afforded cis-diol products in up to 67% yield, with cis-diol/epoxide molar ratio of up to 16.8:1. For electron-deficient alkenes including α,β-unsaturated esters and α,β-unsaturated ketones, their reactions with oxone (2 equiv) catalyzed by 1 (3.5 mol %) for 5 min afforded cis-diols in up to 99% yield with up to >99% substrate conversion. A large-scale cis-dihydroxylation of methyl cinnamate (9.7 g) with oxone (1 equiv) afforded the cis-diol product (8.4 g) in 84% yield with 85% substrate conversion. After catalysis, the L-N4Me2 ligand released due to demetalation can be reused to react with newly added Fe(ClO4)2?4H2O to generate an iron catalyst in situ, which could be used to restart the catalytic alkene cis-dihydroxylation. Mechanistic studies by ESI-MS, isotope labeling studies, and DFT calculations on the 1-catalyzed cis-dihydroxylation of dimethyl fumarate with oxone reveal possible involvement of cis-HO-Fe V O and/or cis-O FeV O species in the reaction; the cis-dihydroxylation reactions involving cis-HO-FeV O and cis-O FeV O species both proceed by a concerted but highly asynchronous mechanism, with that involving cis-HO-FeV O being more favorable due to a smaller activation barrier.
- Chow, Toby Wai-Shan,Wong, Ella Lai-Ming,Guo, Zhen,Liu, Yungen,Huang, Jie-Sheng,Che, Chi-Ming
-
experimental part
p. 13229 - 13239
(2010/12/19)
-
- An expedient procedure for the oxidative cleavage of olefinic bonds with PhI(OAc)2, NMO, and Catalytic OsO4
-
(Figure Presented) PhI(OAc)2 In the presence of OsO4 (cat.) and 2,6-lutidine cleaves oleflnlc bonds to yield the corresponding carbonyl compounds, albeit, In some cases, with a-hydroxy ketones as byproduct. A more practical and clean protocol to effect oxidative cleavage of olefinic bonds involves NMO, OsO4 (cat.), 2,6-lutidine, and PhI(OAc) 2.
- Nicolaou,Adsool, Vikrant A.,Hale, Christopher R. H.
-
supporting information; experimental part
p. 1552 - 1555
(2010/06/16)
-
- Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H2O2
-
A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H2O2 is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions. Under optimized conditions, for diethyl fumarate at least 1000 turnovers could be achieved with only 1.5 equiv. of H2O2 with d/l-diethyl tartrate (cis-diol product) as the sole product. For electron rich alkenes, such as cis-cyclooctene, this catalyst provides for efficient epoxidation.
- Saisaha, Pattama,Pijper, Dirk,Van Summeren, Ruben P.,Hoen, Rob,Smit, Christian,De Boer, Johannes W.,Hage, Ronald,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
-
supporting information; experimental part
p. 4444 - 4450
(2010/11/05)
-
- Photo-irradiation of α-halo carbonyl compounds: A novel synthesis of α-hydroxy- and α,α′-dihydroxyketones
-
The reaction of α-halo ketones (α-iodocycloalkanones, α-bromocycloalkanones, α-iodo-β-alkoxy esters, and α-iodoacyclicketones) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketones in good yields. For α-bromoketones, it was found that α-hydroxylation does not occur. However, α-bromoketones were converted into α-hydroxyketones in the presence of KI. In the case of α,α′-diiodo ketones, α,α′-dihydroxyketones, which up to now have scarcely been reported, were obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′- dihydroxyketones.
- Chai, Wen,Takeda, Akihiro,Hara, Makoto,Ji, Shun-Jun,Horiuchi, C. Akira
-
p. 2453 - 2463
(2007/10/03)
-
- The Mechanism of Product Formation in the Oxidation of 1,2-Cyclooctanediol to Suberic Acid
-
It was shown that the catalytic oxidation of 1,2-cyclooctanediol with hydrogen peroxide to suberic acid is an irreversible process comprising consecutive reactions. The reactivity of the reactant diol and the intermediate products 2-hydroxycyclooctanone and 1,2-cyclooctanedione was compared. To substantiate the consecutive character of product formation, the results of a kinetic study on the molecular geometry of functional alicyclic compounds involved in the process were used. A possible mechanism was proposed for the conversion of products at individual stages of the process of manufacturing suberic acid from 1,2-cyclooctanediol.
- Antonova,Il'in,Kunitskii,Artem'eva,Chabutkina
-
p. 419 - 423
(2007/10/03)
-
- A novel synthesis of α-hydroxy- and α,α′- dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation
-
A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′- diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′- dihydroxyketone.
- Horiuchi, C. Akira,Takeda, Akinori,Chai, Wen,Ohwada, Kishoh,Ji, Shun-Jun,Takahashi, T. Tomoyoshi
-
p. 9307 - 9311
(2007/10/03)
-
- Homogeneous cis-dihydroxylation and epoxidation of olefins with high H2O2 efficiency by mixed manganese/activated carbonyl catalyst system
-
The use of [Mn2O3(tmtacn)2](PF6)2 (tmtacn=1,4,7-trimethyl-1,4,7-triazacyclononane) in combination with glyoxylic acid methylester methyl hemiacetal (GMHA) results in a highly active and hydrogen peroxide efficient catalyst for the epoxidation of olefins as well as the first homogeneous catalytic cis-dihydroxylation system with H2O2 and with turnover numbers up to 420.
- Brinksma, Jelle,Schmieder, Lizette,Van Vliet, Gerbert,Boaron, Rob,Hage, Ronald,De Vos, Dirk E,Alsters, Paul L,Feringa, Ben L
-
p. 2619 - 2622
(2007/10/03)
-
- Oxidation of 1,2-cyclooctanediol with hydrogen peroxide to suberic acid
-
The salient and specific features of 1,2-cyclooctanediol oxidation with hydrogen peroxide to suberic acid in the presence of various catalytic systems were studied. The oxidation of 1,2-cyclooctanediol with such a mild and environmentally friendly oxidizing agent as hydrogen peroxide was shown to yield high-purity suberic acid containing no admixtures of dicarboxylic acids with a smaller number of carbon atoms by carrying out the reaction in a heterogeneous system with a hydrocarbon solvent for the diol.
- Chabutkina,Antonova,Artem'eva,Danilova,Mashina
-
p. 285 - 290
(2007/10/03)
-
- Dehomologation of Aldehydes via Oxidative Cleavage of Silyl Enol Ethers with Aqueous Hydrogen Peroxide Catalyzed by Cetylpyridinium Peroxotungstophosphate under Two-Phase Conditions
-
Dehomologation of aldehydes has been first successfully achieved via oxidative cleavage of silyl enol ethers, derived from aldehydes and trimethylchlorosilane, using aqueous hydrogen peroxide in the presence of a catalytic amount of peroxotungstophophate (PCWP) under phase-transfer conditions. For instance, the oxidation of 1-[(trimethylsilyl)oxy]-1-octene resulting from octanal and Me3SiCl with 35% H2O2 catalyzed by PCWP in dichloromethane at room temperature afforded the one-carbon shorter aldehyde, heptanal, in 79% yield. A variety of silyl enol ethers were also converted into one-carbon shorter aldehydes in good yields. The oxidation under homogeneous conditions using tert-butyl alcohol gave hydrolysis products such as 2-oxooctanol and octanal. It is of interest that [1-(trimethylsilyl)oxy]-1,10-undecadiene involving an enol moiety and a terminal double bond afforded exclusively 9-decenal, in which the enol moiety was selectively oxidized. A plausible reaction path for the oxidative cleavage of silyl enol ethers by the present system has been suggested from the oxidation results of α-[(trimethylsilyl)oxy]styrene.
- Sakaguchi, Satoshi,Yamamoto, Yumiko,Sugimoto, Takuma,Yamamoto, Hiroyo,Ishii, Yasutaka
-
p. 5954 - 5957
(2007/10/03)
-
- Selective oxidation of vinyl ethers and silyl enol ethers with hydrogen peroxide catalyzed by peroxotungstophosphate
-
The oxidation of vinyl and silyl enol ethers with aqueous hydrogen peroxide was first achieved by the use of peroxotungstophosphate (PCWP) as the catalyst. For example, the oxidation of 1-ethoxy-1-octene with a stoichiometric amount of 35% H2O2 in the presence of PCWP (0.5 mol %) in a mixed solvent of methanol and dichloromethane at room temperature gave 1- ethoxy-1-methoxy-2-hydroxyoctane, a synthetic equivalent of 2- hydroxyoctanal, in 70% yield. The oxidation of acyclic silyl enol ethers such as 1-[(trimethylsilyl)oxy]-1-octene under these conditions gave 1-hydroxy-2- octanone in 725 yield, while the same oxidation in dichloromethane alone resulted in cleavage of the enol double bond to form heptanal in 71% yield. Cyclic silyl enol ethers were converted into the corresponding α-hydroxy ketones in 48-71% yields under similar reaction conditions.
- Yamamoto, Hiroyo,Tsuda, Masaya,Sakaguchi, Satoshi,Ishii, Yasutaka
-
p. 7174 - 7177
(2007/10/03)
-
- Conversion of Ketals to Ketones by Nitrogen Dioxide in the Presence of Silica Gel
-
Nitrogen dioxide transforms ketals to ketones in the presence of silica gel under neutral, anhydrous and mild conditions.
- Nishiguchi, Takeshi,Ohosima, Tatsuya,Nishida, Akiko,Fujisaki, Shizuo
-
p. 1121 - 1122
(2007/10/02)
-
- CLEAVAGE OF VICINAL DIOLS BY PYRIDINIUM CHLOROCHROMATE
-
A number of vicinal diols have been oxidatively cleaved by treatment with pyridinium chlorochromate.Thus, good yields of the corresponding aldehydes or ketones can be realized under mild conditions.
- Cisneros, A.,Fernandez, S.,Hernandez, J. F.
-
p. 833 - 838
(2007/10/02)
-