99-49-0Relevant academic research and scientific papers
A sustainable approach towards solventless organic oxidations catalyzed by polymer immobilized Nb(V)-peroxido compounds with H2O2 as oxidant
Ahmed, Kabirun,Gogoi, Sandhya Rani,Islam, Nashreen S.,Saikia, Gangutri,Sultana, Sazida Yasmin,Talukdar, Hiya
, (2021/11/16)
New heterogeneous catalysts comprising of peroxidoniobium(V) complexes immobilized on amino acid grafted cross-linked poly(styrene-divinylbenzene) resin has been developed. Results of FTIR, Raman, NMR, XPS, XRD, EDX, SEM, BET, TGA, and elemental analysis confirmed the successful anchoring of triperoxidoniobium(V), [Nb(O2)3]? species to the host polymer via the pendant amino acid groups. The supported catalysts exhibited excellent performance in epoxidation of styrene and a range of cyclic and terpenic compounds under environmentally acceptable solvent-free condition, with aqueous H2O2 as oxidant. The catalytic protocols provided excellent conversion to the desired epoxide (up to 100%) with selectivity > 99%, TON as high as 1000, and high H2O2 utilization efficiency (92–97%). Moreover, the catalysts efficiently facilitated chemoselective solvent-free oxidation of a variety of thioethers to sulfones at room temperature. Simple operational strategy, easy recyclability for multiple reaction cycles with the consistent activity-selectivity profile are the additional significant attributes of the developed catalytic processes.
An aerobic oxidation of alcohols into carbonyl synthons using bipyridyl-cinchona based palladium catalyst
Cheedarala, Ravi Kumar,Chidambaram, Ramasamy R.,Siva, Ayyanar,Song, Jung Il
, p. 32942 - 32954 (2021/12/02)
We have reported an aerobic oxidation of primary and secondary alcohols to respective aldehydes and ketones using a bipyridyl-cinchona alkaloid based palladium catalytic system (PdAc-5) using oxygen at moderate pressure. ThePdAc-5catalyst was analysed using SEM, EDAX, and XPS analysis. The above catalytic system is used in experiments for different oxidation systems which include different solvents, additives, and bases which are cheap, robust, non-toxic, and commercially available on the industrial bench. The obtained products are quite appreciable in both yield and selectivity (70-85%). In addition, numerous important studies, such as comparisons with various commercial catalysts, solvent systems, mixture of solvents, and catalyst mole%, were conducted usingPdAc-5. The synthetic strategy of oxidation of alcohol into carbonyl compounds was well established and all the products were analysed using1H NMR,13CNMR and GC-mass analyses.
Integrated Electro-Biocatalysis for Amine Alkylation with Alcohols
Pe?afiel, Itziar,Dryfe, Robert A. W.,Turner, Nicholas J.,Greaney, Michael F.
, p. 864 - 867 (2021/01/21)
The integration of electro and bio-catalysis offers new ways of making molecules under very mild, environmentally benign conditions. We show that TEMPO mediated electro-catalytic oxidation of alcohols can be adapted to work in aqueous buffers, with minimal organic co-solvent, enabling integration with biocatalytic reductive amination using the AdRedAm enzyme. The combined process offers a new approach to amine alkylation with native alcohols, a key bond formation in the chemical economy that is currently achieved via precious metal-catalyzed hydrogen-borrowing technologies. The electrobio transformation is effective for primary and secondary alcohols undergoing coupling with allyl, propargyl, benzyl, and cyclopropyl amines, and has been adapted for use with solid-supported AdRedAm for ease of operation.
A silicododecamolybdate/pyridinium-tetrazole hybrid molecular salt as a catalyst for the epoxidation of bio-derived olefins
Nunes, Martinique S.,Neves, Patrícia,Gomes, Ana C.,Cunha-Silva, Luís,Lopes, André D.,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
, (2020/11/27)
The hybrid polyoxometalate (POM) salt (Hptz)4[SiMo12O40]?nH2O (1) (ptz = 5-(2-pyridyl)tetrazole) has been prepared, characterized by X-ray crystallography, and examined as a catalyst for the epoxidation of cis-cyclooctene (Cy) and bio-derived olefins, namely dl-limonene (Lim; a naturally occurring monoterpene found in the rinds of citrus fruits), methyl oleate and methyl linoleate (fatty acid methyl esters (FAMEs) obtained by transesterification of vegetable oils). The crystal structure of 1 consists of α-Keggin-type heteropolyanions, [SiMo12O40]4-, surrounded by space-filling and charge-balancing 2-(tetrazol-5-yl)pyridinium (Hptz+) cations, as well as by a large number of water molecules of crystallization (n = 9). The water molecules mediate an extensive three-dimensional (3D) hydrogen-bonding network involving the inorganic anions and organic cations. For the epoxidation of the model substrate Cy in a nonaqueous system (tert-butylhydroperoxide as oxidant), the catalytic performance of 1 (100% epoxide yield at 24 h, 70 °C) was superior to that of the tetrabutylammonium salt (Bu4N)4[SiMo12O40] (2) (63% epoxide yield at 24 h), illustrating the role of the counterion Hptz+ in enhancing catalytic activity. The hybrid salt 1 was effective for the epoxidation of Lim (69%/85% conversion at 6 h/24 h) and the FAMEs (87–88%/100% conversion at 6 h/24 h), leading to useful bio-based products (epoxides, diepoxides and diol products).
Selective Allylic Oxidation of Terpenic Olefins Using Co-Ag Supported on SiO2 as a Novel, Efficient, and Recyclable Catalyst
Aberkouks, Abderrazak,Mekkaoui, Ayoub Abdelkader,Ait Ali, Mustapha,El Firdoussi, Larbi,El Houssame, Soufiane
, (2020/02/15)
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.
Limonene oxyfunctionalization over Cu-modified silicates employing hydrogen peroxide and t-Butyl hydroperoxide: Reaction pathway analysis
Vaschetti, Virginia M.,Cánepa, Analía L.,Barrera, Deicy,Sapag, Karim,Eimer, Griselda A.,Casuscelli, Sandra G.
, (2018/11/23)
Limonene oxidation over Cu-nanostructured mesoporous materials was studied. Three solids with different copper content were synthesized employing the template-ion exchange method, and physically-chemically analyzed by a multi-technical characterization. The performance of the molecular sieves as catalysts in the liquid phase oxyfunctionalization of limonene, employing hydrogen peroxide (H2O2) or t-butyl hydroperoxide (TBHP) as oxidants was evaluated. All synthesized Cu-MCM materials were active in the reaction. The obtained results showed that the used oxidant had an important influence on the products distribution under the employed conditions. With H2O2, compounds of high added value such as limonene oxide, carveol and carvone were mainly obtained. Meanwhile, with TBHP, limonene hydroperoxide turned out to be the major product. Finally, a reaction mechanism was proposed for each oxidant.
Catalytic oxidation of alcohols using Fe-bTAML and NaClO: Comparing the reactivity of Fe(V)O and Fe(IV)O intermediates
Jana, Sandipan,Thomas, Jithin,Sen Gupta, Sayam
, p. 476 - 482 (2018/11/23)
We demonstrate the selective oxidation of secondary alcohols and activated primary alcohols to their corresponding aldehydes or ketones using Fe-bTAML as the catalyst and sodium hypochlorite (NaClO) as the oxidant. Good to excellent yields of 80%–99% for the carbonyl compounds and turnover numbers up to ～500 was obtained with this catalytic system. The reactions are clean, performed under mild conditions (air, room temperature) and yielded sodium chloride as the only by-product. The yield and turnover number were dependent on the pH of the reaction and this difference was attributed to the different reactive intermediates that was formed at pH 7 and pH 12 (FeV(O) and FeIV(O) respectively). Reactions involving the FeV(O) intermediate oxidize secondary alcohols more efficiently than its FeIV(O) analog. This trend was reversed for the oxidation of activated primary alcohols where reactions involving FeIV(O) afforded much higher TON's. This reactivity trend can be explained from the differences in bond dissociation energy (BDE) of their corresponding one electron reduced species ([FeIV-OH], ～99 kcal/mol; [FeIII-OH], ～83 kcal/mol) as well as their relative stabilities in the solvent during reaction. This catalytic system was found to be unsuitable for nonconjugated primary alcohol due to the formation of the inactive FeIV(OMe) intermediate after one catalytic cycle.
MftD Catalyzes the Formation of a Biologically Active Redox Center in the Biosynthesis of the Ribosomally Synthesized and Post-translationally Modified Redox Cofactor Mycofactocin
Ayikpoe, Richard S.,Latham, John A.
, (2019/09/06)
Mycofactocin (MFT) is a putative ribosomally synthesized and post-translationally modified (RiPP) redox cofactor. The biosynthesis of MFT is encoded by the gene cluster mftABCDEF. While processing of the precursor peptide by MftB, MftC, and MftE has been shown to result in the formation of the small molecule 3-amino-5-[(p-hydroxyphenyl)methyl]-4,4-dimethyl-2-pyrrolidinone (AHDP), no activity has been shown for the putative dehydrogenase MftD and the putative glycosyltransferase MftF. In addition, evidence demonstrating that MFT is a redox cofactor has only been limited to the requirement of mft genes for ethanol assimilation in Mycobacterium smegmatis mc2155. Here, we demonstrate that MftD catalyzes the oxidative deamination of AHDP, forming an α-keto moiety on the resulting molecule, which we call pre-mycofactocin (PMFT). We characterize PMFT by 1D and 2D NMR spectroscopy techniques and by high-resolution mass spectrometry data to solve its structure. We further characterized PMFT by cyclic voltammetry and found its midpoint potential to be ～255 mV. Lastly, we demonstrate that PMFT is a biologically active redox cofactor that oxidizes NADH bound by M. smegmatis carveol dehydrogenase (MsCDH) and can be used by MsCDH in the oxidation of carveol. These data demonstrate for the first time that PMFT functions as a biologically active redox mediator and provides the most direct evidence to date that MFT is a RiPP-derived redox cofactor.
Catalytic epoxidation using dioxidomolybdenum(VI) complexes with tridentate aminoalcohol phenol ligands
Hossain, Md. Kamal,Schachner, J?rg A.,Haukka, Matti,M?sch-Zanetti, Nadia C.,Nordlander, Ebbe,Lehtonen, Ari
, p. 17 - 25 (2018/10/24)
Reaction of the tridentate aminoalcohol phenol ligands 2,4-di-tert-butyl-6-(((2 hydroxyethyl)(methyl)amino)methyl)phenol (H2L1) and 2,4-di-tert-butyl-6-(((1-hydroxybutan-2-yl)amino)methyl)phenol (H2L2) with [MoO2(acac)2] in methanol solutions resulted in the formation of [MoO2(L1)(MeOH)] (1) and [MoO2(L2)(MeOH)] (3), respectively. In contrast, the analogous reactions in acetonitrile afforded the dinuclear complexes [Mo2O2(μ-O)2(L1)2] (2) and [Mo2O2(μ-O)2(L2)2] (4). The corresponding reactions with the potentially tetradentate ligand 3-((3,5-di-tert-butyl-2-hydroxybenzyl)(methyl)amino)propane-1,2-diol (H3L3) led to the formation of the mononuclear complex [MoO2(L3)(MeOH)] (5) in methanol while in acetonitrile solution a trinuclear structure [Mo3O3(μ-O)3(L3)3] (6) was obtained. In both cases, the ligand moiety L3 coordinated in a tridentate fashion. The catalytic activities of complexes 1–6 in epoxidation of five different olefins, S1-5, with tert-butyl hydroperoxide and hydrogen peroxide were studied. The catalytic activities were found to be moderate to good for the reaction of substrate cis-cyclooctene S1, while all complexes were less active in the epoxidation of the more challenging substrates S2-5. The molecular structures of 1, 2, 4 and 6 were determined by single crystal X-ray diffraction analyses.
A Cu-Doped ZIF-8 metal organic framework as a heterogeneous solid catalyst for aerobic oxidation of benzylic hydrocarbons
Nagarjun, Nagarathinam,Dhakshinamoorthy, Amarajothi
, p. 18702 - 18712 (2019/12/09)
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.
