93-56-1Relevant academic research and scientific papers
Synthesis and physical properties of poly(urethane)s using vicinal diols derived from acrylate and styrene monomers
Akbulut, Huseyin,Yoshida, Yoshiaki,Yamada, Shuhei,Endo, Takeshi
, p. 799 - 805 (2019)
We describe the utilization of four kinds of diol derivatives, representing structural similarity to the well-known and commercially available vinyl monomers such as acrylate, acrylamide, styrene, and N-substituted maleimide. The vinyl monomers are readily converted by dihydroxylation reaction to afford the vicinal diol. The synthesis of poly(urethane)s was performed by the reaction of the vicinal diol with two model diisocyanates, including methylene diphenyl isocyanate (MDI) and hexamethylene diisocyanate (HDI) in the presence of dibutyltin dilaurate to form a series of poly(urethane)s, and the effect of vicinal diol containing a side chain inherited from vinyl monomers on their thermal and mechanical properties was investigated using thermogravimetric analysis, differential scanning calorimetry, and tensile test.
(N-Salicylidene)aniline derived schiff base complexes of methyltrioxorhenium(VII): Ligand influence and catalytic performance
Zhou, Ming-Dong,Yu, Yang,Canape, Alejandro,Jain, Kavita R.,Herdtweck, Eberhardt,Li, Xiao-Rong,Li, Jun,Zang, Shu-Liang,Kuehn, Fritz E.
, p. 411 - 418 (2009)
Methyltrioxorhenium(VII) (MTO) readily forms 1:1 adducts with several N-(salicylidene)aniline derived Schiff bases. If the aromatic rings of the N-(salicylidene)aniline ligands display non-donating or electron withdrawing substituent groups, the resulting MTO adducts show good activities in olefin epoxidations. However, steric effects seem to play a major role, leading often to instable o- and m-Schiff base-MTO adducts, while p-substituted Schiff bases usually lead to more stable adducts. In catalysis, electron-withdrawing substituents on the aniline moiety lead to better catalysts than electron donating ones. The gap between good catalysts and instable or non-existing compounds, however, is small. The general tendency, however, that good donors on the Schiff base Iigands lead to shorter Re - O(Schiff base) bridges and lower catalytic activity, while the opposite is true with acceptor ligands on the Schiff bases, seems to be quite clear.
Catalytic oxygen atom transfer promoted by tethered Mo(VI) dioxido complexes onto silica-coated magnetic nanoparticles
Colaiezzi, Roberta,Crucianelli, Marcello,Di Giuseppe, Andrea,Ferella, Francesco,Lazzarini, Andrea,Paolucci, Valentina
, (2021/11/30)
The preparation of three novel active and stable magnetic nanocatalysts for the selective liquid-phase oxidation of several olefins, has been reported. The heterogeneous systems are based on the coordination of cis-MoO2 moiety onto three different SCMNP@Si-(L1-L3) magnetically active supports, functionalized with silylated acylpyrazolonate ligands L1, L2 and L3. Nanocatalysts thoroughly characterized by ATR-IR spectroscopy, TGA and ICP-MS analyses, showed excellent catalytic performances in the oxidation of conjugated or unconjugated olefins either in organic or in aqueous solvents. The good magnetic properties of these catalytic systems allow their easy recyclability, from the reaction mixture, and reuse over five runs without significant decrease in the activity, either in organic or water solvent, demonstrating their versatility and robustness.
Enhancing the Catalytic Performance of Group I, II Metal Halides in the Cycloaddition of CO2to Epoxides under Atmospheric Conditions by Cooperation with Homogeneous and Heterogeneous Highly Nucleophilic Aminopyridines: Experimental and Theoretical Study
Natongchai, Wuttichai,Posada-Pérez, Sergio,Phungpanya, Chalida,Luque-Urrutia, Jesús Antonio,Solà, Miquel,D'Elia, Valerio,Poater, Albert
, p. 2873 - 2886 (2022/02/10)
Compared to metal-organic complexes and transition-metal halides, group I metal halides are attractive catalysts for the crucial cycloaddition reaction of CO2to epoxides as they are ubiquitously available and inexpensive, have a low molecular weight, and are not based on (potentially) endangered metals, especially for the case of sodium and potassium. Nevertheless, given their low intrinsic catalytic efficiency, they require the assistance of additional catalytic moieties. In this work, we show that by exploiting the high nucleophilicity of opportunely designed aminopyridines, catalytic systems based on alkaline metals can be formed, which allow the cycloaddition of CO2to epoxides to proceed under atmospheric pressure at moderate temperatures. Importantly, the aminopyridine nucleophiles can be applied in their heterogenized form, leading to a recyclable catalytic system. An investigation of the reaction mechanism by density functional theory calculations shows that metal halide complexes and nucleophilic pyridines can work as a dual cooperative catalytic system where the use of aminopyridines leads to lower energy barriers for the opening of the epoxide ring, and halide-adducts are involved in the subsequent steps of CO2insertion and ring closure.
Self-assembly of reverse micelle nanoreactors by zwitterionic polyoxometalate-based surfactants for high selective production of β?hydroxyl peroxides
An, Sai,Chang, Wen,Hu, Guicong,Qi, Bo,Song, Yu-Fei
supporting information, (2022/03/08)
Surfactants with polyoxometalates (POMs) as polar head groups have shown fascinating self-assembly behaviors and various functional applications. However, self-assembly them into reverse micelles is still challenging owing to the large molecular size and intermolecular strong electrostatic repulsions of POM heads. In this work, a zwitterionic POM-based surfactant was synthesized by covalently grafting two cationic long alkyl tails onto the lacunary site of [PW11O39]7?. With decreased electrostatic repulsions and increased hydrophobic effect, the POM-based reverse micelles with an average diameter of 5 nm were obtained. Interestingly, when these reverse micelles were applied for catalyzing the oxidation of styrene, an unprecedented β?hydroxyl peroxide compound of 2?hydroxyl-2-phenylethan-1?tert-butylperoxide was produced in high selectivity of 95.2%. In comparison, the cetyltrimethylammonium electrostatically encapsulated POMs mainly generated the epoxides or 1,2-diols. A free radical mechanism was proposed for the oxidation reaction catalyzed by the zwitterionic POM surfactants.
Oxoammonium Salt-Mediated Regioselective Vicinal Dioxidation of Alkenes: Relying on Transient and Persistent Nitroxides
Chen, Fei,Ge, Ming-Jing,Liu, Shi-Yu,Wu, Lu-Yan,Yang, Hao,Yang, Qing-Yun,Zheng, Yang,Zhu, Xin-Yue
supporting information, p. 8533 - 8538 (2021/11/17)
A novel, easy-to-handle, and regioselective vicinal dioxidation of alkenes under transition metal and organic peroxide free conditions has been developed. This approach uses N-hydroxyphthalimide and its analogues as the transient nitroxyl-radical precursors and 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPO+BF4-) as the oxidant as well as the source of persistent nitroxide. By employing this method, multifarious structurally important dioxidation products were efficiently synthesized from simple alkenes and complex bioactive molecule derivatives.
Reaction pathways and deactivation mechanisms of isostructural Cr and Fe MIL-101 during liquid-phase styrene oxidation by hydrogen peroxide
Sarazen, Michele L.,Yang, Rachel A.
, p. 5282 - 5296 (2021/08/16)
Isostructural Cr and Fe nanoporous MIL-101, synthesized without mineralizing agents, are investigated for styrene oxidation utilizing aqueous hydrogen peroxide to yield valuable oxygenates for chemical synthesis applications. Styrene conversion rates and oxygenate product distributions both depend on metal identity, as MIL-101(Fe) is more reactive for total styrene oxidation and is more pathway selective, preferring aldehyde (benzaldehyde) formation at the α-carbon to the aromatic ring, where MIL-101(Cr) sustains epoxide (styrene oxide) production at the same α-carbon. These pathways often involve hydrogen peroxide derived radical intermediates (O, -HOO, -HO-) and metallocycle transition states. We postulate that the higher reactivity of one of these surface intermediates, Fe(iv)O relative to Cr(iv)O, leads to higher styrene oxidation rates for MIL-101(Fe), while higher electrophilicity of Cr(iii)-OOH intermediates translates to the higher styrene oxide selectivity observed for MIL-101(Cr). Secondary styrene oxide and benzaldehyde conversions are observed over both analogs, but the former is more prevalent over MIL-101(Fe) due to higher Lewis/Br?nsted acid site density and strength compared to MIL-101(Cr). Recyclability experiments combined with characterization via XRD, SEM/EDXS, and FT-IR and UV-vis spectroscopies show that the nature of MIL-101(Fe) sites does not change significantly with each cycle, whereas MIL-101(Cr) suffers from metal leaching, which impacts styrene conversion rates and product distribution. Both catalysts require active site regeneration, though MIL-101(Fe) sites are more susceptible to reactivation, even under mild conditions. Finally, examination of styrene conversion for three unique synthesized phases of MIL-101(Cr) rationalizes that nodal defects are largely responsible for observed reactivity and selectivity but predispose the framework to metal leaching as a predominant deactivation mechanism.
Evaluation of the protolytic equilibria and catalytic activity of sugar-based Schiff base ligands with VO2+ and MoO22+ cations in sulfoxidation and epoxidation reactions
Chylewska, Agnieszka,D?browska, Aleksandra,Karman, Marta,Madejska, Katarzyna,Romanowski, Grzegorz
, (2021/09/28)
Based on the two anomeric methyl 3-amino-2,3-dideoxy-D-arabino-hexopyranosides ten new sugar-modified Schiff base ligands have been synthesized after monocondensation reaction with five o-hydroxyaromatic aldehydes, i.e. salicylaldehyde and its five para-s
Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
, (2021/06/21)
Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
Photo-Induced Dihydroxylation of Alkenes with Diacetyl, Oxygen, and Water
Masuda, Yusuke,Ikeshita, Daichi,Murakami, Masahiro
, (2021/02/09)
Herein reported is a photo-induced production of vicinal diols from alkenes under mild reaction conditions. The present dihydroxylation method using diacetyl (= butane-2,3-dione), oxygen, and water dispenses with toxic reagents and intractable waste generation.
