811-98-3Relevant academic research and scientific papers
Experimental study on the mechanism of gas-phase aromatic nitration by protonated methyl nitrate
Aschi, Massimiliano,Attinà, Marina,Cacace, Fulvio,Ricci, Andreina
, p. 9535 - 9542 (1994)
The mechanism of gas-phase aromatic substitution by (CH3ONO2)H+ ions has been studied by a combination of FT-ICR mass spectrometry and atmospheric pressure radiolytic techniques. Clarifying a long-standing ambiguity, the ICR results characterize the CH3OH-NO2+ complex (1), in essence a nitronium ion solvated by a methanol molecule, as the nitrating agent, whereas the CH3NO2H+ isomer (2) is devoid of nitrating properties and reacts with benzene exclusively as a Br?nsted acid. Indeed, the reaction with benzene has been exploited as an ICR "titration" technique to evaluate the relative abundances of 1 and 2 in mixed populations of (CH3ONO2)H+ ions from different preparative procedures. Radiolytic nitration of p-H-toluene-d7 and p-D-toluene-h7 leads to intraannular hydron migration from the ipso nitrated position, whose rate has been estimated to be ca. 1.6 × 106 s-1 at 315 K. The mutually supporting evidence from the ICR and the radiolytic experiments outlines a reaction mechanism involving preliminary formation of a Wheland intermediate from the attack of 1 on the arene, followed by its isomerization into the more stable O-protonated nitrobenzene structure via a proton shift whose rate is estimated to be ca. 3.6 × 107s-1 at 315 K. The results are compared with those of a recent theoretical analysis of the mechanism of aromatic nitration by isomeric (CH3ONO2)H+ ions, and their correlation with condensed-phase nitration is briefly discussed.
Hydrogenation of CO2 to Methanol by Pt Nanoparticles Encapsulated in UiO-67: Deciphering the Role of the Metal-Organic Framework
Gutter?d, Emil S.,Lazzarini, Andrea,Fjermestad, Torstein,Kaur, Gurpreet,Manzoli, Maela,Bordiga, Silvia,Svelle, Stian,Lillerud, Karl P.,Skúlason, Egill,?ien-?Degaard, Sigurd,Nova, Ainara,Olsbye, Unni
supporting information, p. 999 - 1009 (2020/02/20)
Metal-organic frameworks (MOFs) show great prospect as catalysts and catalyst support materials. Yet, studies that address their dynamic, kinetic, and mechanistic role in target reactions are scarce. In this study, an exceptionally stable MOF catalyst consisting of Pt nanoparticles (NPs) embedded in a Zr-based UiO-67 MOF was subject to steady-state and transient kinetic studies involving H/D and 13C/12C exchange, coupled with operando infrared spectroscopy and density functional theory (DFT) modeling, targeting methanol formation from CO2/H2 feeds at 170 °C and 1-8 bar pressure. The study revealed that methanol is formed at the interface between the Pt NPs and defect Zr nodes via formate species attached to the Zr nodes. Methanol formation is mechanistically separated from the formation of coproducts CO and methane, except for hydrogen activation on the Pt NPs. Careful analysis of transient data revealed that the number of intermediates was higher than the number of open Zr sites in the MOF lattice around each Pt NP. Hence, additional Zr sites must be available for formate formation. DFT modeling revealed that Pt NP growth is sufficiently energetically favored to enable displacement of linkers and creation of open Zr sites during pretreatment. However, linker displacement during formate formation is energetically disfavored, in line with the excellent catalyst stability observed experimentally. Overall, the study provides firm evidence that methanol is formed at the interface of Pt NPs and linker-deficient Zr6O8 nodes resting on the Pt NP surface.
Formation of Glyoxylic Acid in Interstellar Ices: A Key Entry Point for Prebiotic Chemistry
Eckhardt, André K.,Bergantini, Alexandre,Singh, Santosh K.,Schreiner, Peter R.,Kaiser, Ralf I.
supporting information, p. 5663 - 5667 (2019/03/29)
With nearly 200 molecules detected in interstellar and circumstellar environments, the identification of the biologically relevant α-keto carboxylic acid, glyoxylic acid (HCOCOOH), is still elusive. Herein, the formation of glyoxylic acid via cosmic-ray driven, non-equilibrium chemistry in polar interstellar ices of carbon monoxide (CO) and water (H2O) at 5 K via barrierless recombination of formyl (HCO) and hydroxycarbonyl radicals (HOCO) is reported. In temperature-programmed desorption experiments, the subliming neutral molecules were selectively photoionized and identified based on the ionization energy and distinct mass-to-charge ratios in combination with isotopically labeled experiments exploiting reflectron time-of-flight mass spectrometry. These studies unravel a key reaction path to glyoxylic acid, an organic molecule formed in interstellar ices before subliming in star-forming regions like SgrB2(N), thus providing a critical entry point to prebiotic organic synthesis.
Synthesis of ethanol via a reaction of dimethyl ether with CO2 and H2
Qian, Qingli,Cui, Meng,Zhang, Jingjing,Xiang, Junfeng,Song, Jinliang,Yang, Guanying,Han, Buxing
supporting information, p. 206 - 213 (2018/01/12)
Ethanol is currently produced via the catalytic hydration of ethylene or fermentation of foods. The synthesis of ethanol from cheap and renewable CO2 is of great importance, but the state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we show a strategy of ethanol synthesis from CO2, dimethyl ether (DME) and H2. The reaction can be effectively promoted with a Ru-Co bimetallic catalyst using LiI as a promoter in 1,3-dimethyl-2-imidazolidinone (DMI) solvent. The predominant product of this reaction was ethanol and the selectivity of ethanol in total products could reach 71.7 C-mol%. The selectivity of ethanol in the liquid product could reach 94.1%, which was higher than the reported routes using CO2/CO. To the best of our knowledge, this is the first work on ethanol synthesis from DME, CO2 and H2. The reaction mechanism is discussed based on a series of control experiments.
Aqueous phase hydrodeoxygenation of polyols over Pd/WO3-ZrO2: Role of Pd-WO3 interaction and hydrodeoxygenation pathway
Liu, Changjun,Sun, Junming,Brown, Heather M.,Marin-Flores, Oscar G.,Bays, J. Timothy,Karim, Ayman M.,Wang, Yong
, p. 103 - 109 (2016/05/11)
Aqueous phase processing of biomass derived sugar alcohols is one of the promising routes to convert biomass into fuels and chemicals. Bifunctional catalysts are critical in the aqueous phase hydrodeoxygenation of sugar alcohol. Understanding the interaction between metal and acidic metal oxides as well as the hydrodeoxygenation pathways will help develop more efficient bifunctional catalysts. Here, tungstated zirconia supported palladium catalysts were prepared and further characterized using nitrogen sorption, X-ray diffraction, FT-IR analysis of adsorbed pyridine, CO chemisorption and diffuse reflectance UV-vis. Strong interaction between palladium and WO3 in addition to a synergetic effect of the acidic and metallic sites were found to promote the aqueous phase hydrodeoxygenation of ethylene glycol. H-D exchange experiments using 13C{1H} NMR spectroscopy confirmed that the aqueous phase hydrodeoxygenation follows a dehydration-hydrogenation pathway. The hydrogenation of the dehydration products shifts the dehydration-hydration equilibrium toward the dehydration pathway and leads to highly selective C-O cleavage.
Transfer hydrogenation of organic formates and cyclic carbonates: An alternative route to methanol from carbon dioxide
Kim, Seung Hyo,Hong, Soon Hyeok
, p. 3630 - 3636 (2015/02/19)
Transfer hydrogenation of organic formates and cyclic carbonates was achieved for the first time using a readily available ruthenium catalyst. Nontoxic and economical 2-propanol was used, both as a solvent and hydrogen source, without the need of using flammable H2 gas under high pressure. This method provides an indirect strategy to produce methanol from carbon dioxide under mild conditions as well as an operationally simple and environmentally benign way to reduce formates and carbonates.
Using reduced catalysts for oxidation reactions: Mechanistic studies of the "periana-catalytica" system for CH4 oxidation
Mironov, Oleg A.,Bischof, Steven M.,Konnick, Michael M.,Hashiguchi, Brian G.,Ziatdinov, Vadim R.,Goddard, William A.,Ahlquist, Maisrten,Periana, Roy A.
supporting information, p. 14644 - 14658 (2013/10/22)
Designing oxidation catalysts based on CH activation with reduced, low oxidation state species is a seeming dilemma given the proclivity for catalyst deactivation by overoxidation. This dilemma has been recognized in the Shilov system where reduced PtII is used to catalyze methane functionalization. Thus, it is generally accepted that key to replacing Pt IV in that system with more practical oxidants is ensuring that the oxidant does not over-oxidize the reduced PtII species. The "Periana-Catalytica" system, which utilizes (bpym)Pt IICl2 in concentrated sulfuric acid solvent at 200 C, is a highly stable catalyst for the selective, high yield oxy-functionalization of methane. In lieu of the over-oxidation dilemma, the high stability and observed rapid oxidation of (bpym)PtIICl2 to PtIV in the absence of methane would seem to contradict the originally proposed mechanism involving CH activation by a reduced PtII species. Mechanistic studies show that the originally proposed mechanism is incomplete and that while CH activation does proceed with PtII there is a solution to the over-oxidation dilemma. Importantly, contrary to the accepted view to minimize PtII overoxidation, these studies also show that increasing that rate could increase the rate of catalysis and catalyst stability. The mechanistic basis for this counterintuitive prediction could help to guide the design of new catalysts for alkane oxidation that operate by CH activation.
Stepwise photocatalytic dissociation of methanol and water on TiO 2(110)
Guo, Qing,Xu, Chenbiao,Ren, Zefeng,Yang, Wenshao,Ma, Zhibo,Dai, Dongxu,Fan, Hongjun,Minton, Timothy K.,Yang, Xueming
supporting information; experimental part, p. 13366 - 13373 (2012/10/07)
We have investigated the photocatalysis of partially deuterated methanol (CD3OH) and H2O on TiO2(110) at 400 nm using a newly developed photocatalysis apparatus in combination with theoretical calculations. Photocatalyzed products, CD2O on Ti5c sites, and H and D atoms on bridge-bonded oxygen (BBO) sites from CD3OH have been clearly detected, while no evidence of H2O photocatalysis was found. The experimental results show that dissociation of CD3OH on TiO2(110) occurs in a stepwise manner in which the O-H dissociation proceeds first and is then followed by C-D dissociation. Theoretical calculations indicate that the high reverse barrier to C-D recombination and the facile desorption of CD2O make photocatalytic methanol dissociation on TiO2(110) proceed efficiently. Theoretical results also reveal that the reverse reactions, i.e, O-H recombination after H2O photocatalytic dissociation on TiO2(110), may occur easily, thus inhibiting efficient photocatalytic water splitting.
Enantioselective synthesis of stephacidin B
Herzon, Seth B.,Myers, Andrew G.
, p. 5342 - 5344 (2007/10/03)
We describe an enantioselective synthetic route to the antiproliferative alkaloid stephacidin B (1) proceeding in 18 steps and 4.0% yield from 4,4-(ethylenedioxy)-2,2-dimethylcyclohexanone (3). Key features of the synthetic sequence include the use of the Corey-Bakshi-Shibata (CBS) reduction to introduce asymmetry early in the synthetic route, use of the novel electrophile N-(tert-butoxycarbonyl)-5-(isopropylsulfonyloxymethyl)-2,3-dihydropyrrole in a stereoselective enolate alkylation, a diastereoselective Strecker-type addition of hydrogen cyanide to an N-Boc enamine substrate in the solvent hexafluoroisopropanol, platinum-catalyzed nitrile hydrolysis under neutral conditions, cyclization of an acylamino radical intermediate to form the diketopiperazine core of stephacidin B, and implementation of a convergent procedure for introduction of the key 3-alkylidene-3H-indole 1-oxide functional group in the final stage of the route to prepare the structure 2, previously proposed to be the fungal metabolite avrainvillamide (17 steps, 4.2% yield). We observed that synthetic (-)-2 dimerized in the presence of triethylamine to form (+)-stephacidin B (>95%). We also obtained evidence that 2 can form 1 under mild conditions, and that 2 reacts with nucleophiles, such as methanol, by conjugate addition. Copyright
Methanol formation from dichloromethane under hydrothermal conditions
Yamasaki, Yuki,Enomoto, Heiji,Yamasaki, Nakamichi,Nakahara, Masaru
, p. 83 - 84 (2007/10/03)
CH2Cl2 (1 mole) mixed with NaOH (2 moles) was treated under hydrothermal conditions at 250 °C. The chlorinated methane was completely hydrolyzed to form methanol and the formate by the Cannizzaro reaction. The reactant and products were analyzed by 1H-, 2H-, and 13C-NMR. Solvent isotope effect on the transformation was also investigated. The hazardous and environmentally troublesome organic solvent was safely converted into the useful compounds.
