- A Light-Releasable Potentially Prebiotic Nucleotide Activating Agent
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Investigations into the chemical origin of life have recently benefitted from a holistic approach in which possible atmospheric, organic, and inorganic systems chemistries are taken into consideration. In this way, we now report that a selective phosphate activating agent, namely methyl isocyanide, could plausibly have been produced from simple prebiotic feedstocks. We show that methyl isocyanide drives the conversion of nucleoside monophosphates to phosphorimidazolides under potentially prebiotic conditions and in excellent yields for the first time. Importantly, this chemistry allows for repeated reactivation cycles, a property long sought in nonenzymatic oligomerization studies. Further, as the isocyanide is released upon irradiation, the possibility of spatially and temporally controlled activation chemistry is thus raised.
- Mariani, Angelica,Russell, David A.,Javelle, Thomas,Sutherland, John D.
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Read Online
- Ethanol gas-phase ammoxidation to acetonitrile: The reactivity of supported vanadium oxide catalysts
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New insights on the gas-phase ammoxidation of ethanol to acetonitrile over supported vanadia catalysts were obtained by means of reactivity experiments (in ethanol ammoxidation and oxidation) as well as in situ Raman and DRIFT spectroscopy. It was found that the rate-determining step during the redox process depends on the support type. In the case of V2O5/ZrO2, the V oxidation state under reaction conditions is closer to V5+, whereas with V2O5/TiO2, the reduction of V5+ is faster than the re-oxidation of the corresponding reduced V species by O2; thus, the V oxidation state under steady state conditions is lower than for V2O5/ZrO2. In the latter catalyst, the more oxidized V species is responsible for ammonia activation and reaction with the intermediate acetaldehyde, leading in the end to a better acetonitrile yield than with V2O5/TiO2. It was also found that V2O5/ZrO2 is more selective to acetaldehyde than V2O5/TiO2. With the former catalyst, ethanol is able to reduce V2O5 only to a limited extent. Conversely, V2O5/TiO2 is readily reduced by ethanol but this reduced V species is responsible for an unselective oxidation of the alcohol, giving more CO and CO2.
- Folco,Velasquez Ochoa,Cavani,Ott,Janssen
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Read Online
- Interactions of the aromatic cavity of rigid calix[4]arene cone conformers with acid CH3 and CH2 containing guests in apolar solvents
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The effect of the acidity of CH groups within the guests on the binding ability of the aromatic cavity of rigid cone conformers of p-tert-butylcalix[4]arene toward guests containing acid CH3 and CH2 groups have been investigated in a
- Arduini, Arturo,Giorgi, Giovanna,Pochini, Andrea,Secchi, Andrea,Ugozzoli, Franco
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Read Online
- Product selectivity controlled by manganese oxide crystals in catalytic ammoxidation
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The performances of heterogeneous catalysts can be effectively tuned by changing the catalyst structures. Here we report a controllable nitrile synthesis from alcohol ammoxidation, where the nitrile hydration side reaction could be efficiently prevented by changing the manganese oxide catalysts. α-Mn2O3 based catalysts are highly selective for nitrile synthesis, but MnO2-based catalysts including α, β, γ, and δ phases favour the amide production from tandem ammoxidation and hydration steps. Multiple structural, kinetic, and spectroscopic investigations reveal that water decomposition is hindered on α-Mn2O3, thus to switch off the nitrile hydration. In addition, the selectivity-control feature of manganese oxide catalysts is mainly related to their crystalline nature rather than oxide morphology, although the morphological issue is usually regarded as a crucial factor in many reactions.
- Hui, Yu,Luo, Qingsong,Qin, Yucai,Song, Lijuan,Wang, Hai,Wang, Liang,Xiao, Feng-Shou
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p. 2164 - 2172
(2021/09/20)
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- PROCESS FOR PRODUCING METHACRYLIC ACID OR METHACRYLIC ACID ESTERS
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The present invention relates to a process for producing methacrylic acid or methacrylic acid esters. The present invention is directed to a new process for the production of methacrylic acid or alkyl methacrylate starting from Acrolein, which is available from glycerol or propane.
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Page/Page column 15-16
(2020/03/02)
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- PRODUCTION OF ACETONITRILE AND/OR HYDROGEN CYANIDE FROM AMMONIA AND METHANOL
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The invention relates to a process for producing a product gas comprising acetonitrile and/or hydrogen cyanide from a feed stream comprising ammonia and methanol over a solid catalyst comprising a support, a first metal and a second metal on the support, wherein the first metal and the second metal are in the form of a chemical compound, wherein the first metal is Fe, Ru or Co and the second metal is Sn, Zn, or Ge. The pressure is ambient pressure or higher and the temperature lies in a range from about 400° C. to about 700° C. Thus, the process for producing acetonitrile and/or hydrogen cyanide from ammonia and methanol may be catalyzed by a single catalyst and may be carried out in a single reactor. The invention also relates to a catalyst, a method for activating a catalyst and use of a catalyst for catalysing production of acetonitrile and/or hydrogen cyanide from ammonia and methanol.
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Paragraph 0046-0049
(2020/04/10)
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- Method of preparation of ethylamine or acetonitrile by reductive amination of ethanol
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The present invention relates to a catalyst for manufacturing ethylamine and a method for manufacturing the same. More specifically, the present invention relates to: a nickel-supported catalyst for manufacturing ethylamine or acetonitrile which has impregnated nickel on a supporter as a catalyst capable of efficiently manufacturing ethylamine or acetonitrile at a normal pressure or lower by reacting ethanol with ammonia, a method for manufacturing the same, and a method for manufacturing ethylamine using the same.COPYRIGHT KIPO 2019
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Paragraph 0095-0099; 0107; 0178; 0187; 0196
(2019/06/22)
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- ZEOLITE CATALYST
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The present disclosure relates to the preparation of pyridine derivatives, such as α-picoline or α-parvoline, and catalysts useful for the selective preparation of such pyridine derivatives. Particularly, the present disclosure relates to the selective preparation of certain pyridine derivative using dealuminated zeolite catalysts.
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Paragraph 0101; 0103; 0120; 0122; 0130; 0136-0137
(2019/05/22)
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- Transition-metal-free addition reaction for the synthesis of 3-(aminobenzylidene/aminoalkylidene)indolin-2-ones and its synthetic applications
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A novel and efficient transition-metal-free approach for the exclusive synthesis of Z-3-(aminobenzylidene/aminoalkylidene)indolin-2-ones in high yield from 2-oxindole and aryl/alkyl nitrile in the presence of LiOtBu and 2,2′-bipyridine system is described. In addition, we disclosed a new approach towards the metal-free fluorination using selectfluor and the C=C bond cleavage using CuI and environmentally benign O2.
- Bisht, Girish Singh,Gnanaprakasam, Boopathy
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supporting information
p. 13516 - 13527
(2019/10/19)
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- Propane Versus Ethane Ammoxidation on Mixed Oxide Catalytic Systems: Influence of the Alkane Structure
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Abstract: Catalysts from three different catalytic systems, Ni–Nb–O, Mo–V–Nb–Te–O and Sb–V–O, have been prepared, characterized, and tested during both ethane and propane ammoxidation reactions, in order to obtain acetonitrile and acrylonitrile, respectively. The catalytic results show that Mo–V–Nb–Te–O and Sb–V–O catalyze propane ammoxidation but are inactive for ethane ammoxidation whereas Ni–Nb–O catalysts catalyze both, ethane and propane ammoxidation. The activity results, and the characterization of fresh and used catalysts along with some data from previous studies, indicate that the ammoxidation reaction mechanism that occurs in these catalytic systems is different. In the case of Mo–V–Nb–Te–O and Sb–V–O, two active sites appear to be involved. In the case of Ni–Nb–O catalysts, only one site seems to be involved, which underlines that the mechanism is different and take place via a different intermediate. These catalysts activate the methyl groups in ethane, on the contrary, neither ethane nor ethylene appear to adsorb on the Mo–V–Nb–Te–O and Sb–V–O active sites. Graphical Abstract: [Figure not available: see fulltext.]
- Guerrero-Pérez, M. Olga,Rojas-García, Elizabeth,López-Medina, Ricardo,Ba?ares, Miguel A.
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p. 1838 - 1847
(2016/10/18)
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- New composite catalysts for the synthesis of acetonitrile from ethanol and ammonia, prepared using calcium aluminates (Talyum)
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Experiments on direct synthesis of acetonitrile from ethanol, ammonia, and hydrogen at 513–573 K in the presence of new Cu-, Cu–Zn–(Zr)-, and Cu–Mg-containing composite catalysts prepared using calcium aluminates (Talyum, technical-grade calcium aluminate) were performed The following results were reached: ethanol conversion 96.0–99.0%, selectivity with respect to acetonitrile 99.0%, and acetonitrile output exceeding the reported level by a factor of 1.2–1.4. The new technology can be implemented in industry.
- Belov,Markov,Sova,Golosman,Nechugovskii
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p. 414 - 420
(2016/07/06)
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- Transition-Metal-Free Deacylative Cleavage of Unstrained C(sp3)-C(sp2) Bonds: Cyanide-Free Access to Aryl and Aliphatic Nitriles from Ketones and Aldehydes
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A transition-metal-free deacylative C(sp3)-C(sp2) bond cleavage for the synthetically practical oxidative amination of ketones and aldehydes to nitriles is first described, using cheap and commercially abundant NaNO2 as the oxidant and the nitrogen source. Various nitriles bearing aryl, heteroaryl, alkyl, and alkenyl groups could be smoothly obtained from ketones and aldehydes in high yields, avoiding highly toxic cyanides or transition metals.
- Ge, Jing-Jie,Yao, Chuan-Zhi,Wang, Mei-Mei,Zheng, Hong-Xing,Kang, Yan-Biao,Li, Yadong
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supporting information
p. 228 - 231
(2016/02/03)
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- Propane ammoxidation on Bi promoted MoVTeNbOx oxide catalysts: Effect of reaction mixture composition
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MoVTeNbO catalysts were characterized with XRD, XPS, and FTIR techniques and tested in the ammoxidation of propane. Bismuth-modified MoVTeNbO catalysts showed a higher acrylonitrile yield than the base four-component system. The effect of the reaction mixture composition (C3H8, NH3 and O2) on selectivity towards different products was studied at propane conversion above 80%. The favorable effect of bismuth promoter on the selectivity towards acrylonitrile was explained by suppression of acrylonitrile transformation connected with decreasing acidity of the catalyst.
- Andrushkevich, Tamara V.,Popova, Galina Y.,Chesalov, Yuriy A.,Ischenko, Evgeniya V.,Khramov, Mikhail I.,Kaichev, Vasily V.
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p. 109 - 117
(2015/09/28)
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- Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry
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Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds.
- Wang, Zhe-Chen,Cole, Callie A.,Demarais, Nicholas J.,Snow, Theodore P.,Bierbaum, Veronica M.
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p. 10700 - 10709
(2015/09/28)
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- Mechanistic insights into the oxidative dehydrogenation of amines to nitriles in continuous flow
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The oxidative dehydrogenation of various aliphatic amines to their corresponding nitrile compounds using RuO2/Al2O3 catalysts in air was successfully applied to a continuous flow reaction. Conversions of amines (up to >99%) and yields of nitriles (up to 77%) varied depending on reaction conditions and the amine utilised. The presence of water was found to be important for the activity and stability of the RuO2/Al2O3 catalyst. The Hammett relationship and in situ infrared spectroscopy were applied to divulge details about the catalytic mechanism of the oxidative dehydrogenation of amines over RuO2/Al2O3 catalysts.
- Corker, Emily C.,Ruiz-Martínez, Javier,Riisager, Anders,Fehrmann, Rasmus
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p. 5008 - 5015
(2015/11/03)
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- Nitrile imines and nitrile ylides: Rearrangements of benzonitrile N-methylimine and benzonitrile dimethylmethylide to azabutadienes, carbodiimides, and ketenimines. chemical activation in thermolysis of azirenes, tetrazoles, oxazolones, isoxazolones, and oxadiazolones
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Flash vacuum thermolysis (FVT) of 1-methyl-5-phenyltetrazole (5b), 2-methyl-5-phenyltetrazole (1b), and 3-methyl-5-phenyl-1,3,4-oxadiazol-2(3H)-one (3b) affords the nitrile imine (2b), which rearranges in part to N-methyl-N′-phenylcarbodiimide (7b). Another part of 2b undergoes a 1,4-H shift to the diazabutadiene (13). 13 undergoes two chemically activated decompositions, to benzonitrile and CH2=NH and to styrene and N 2. FVT of 2,2-dimethyl-4-phenyl-oxazol-5(2H)-one (16) at 400 C yields 3-methyl-1-phenyl-2-azabutadiene (18) in high yield. In contrast, FVT of 3,3-dimethyl-2-phenyl-1-azirene (21) at 600 C or 4,4-dimethyl-3-phenyl- isoxazolone (20) at 600 C affords only a low yield of azabutadiene (18) due to chemically activated decomposition of 18 to styrene and acetonitrile. There are two reaction paths from azirene (21): one (path a) leading to nitrile ylide (17) and the major products styrene and acetonitrile and the other (path b) leading to the vinylnitrene (22) and ketenimine (23). The nitrile ylide PhC -=N+=C(CH3)2 (17) is implicated as the immediate precursor of azabutadiene (18). FVT of either 3-phenylisoxazol- 5(4H)one (25) or 2-phenylazirene (26) at 600 C affords N-phenylketenimine (28). The nitrile ylide PhC-=N+=CH2 (30) is postulated as a reversibly formed intermediate. N-Phenylketenimine (28) undergoes chemically activated free radical rearrangement to benzyl cyanide. The mechanistic interpretations are supported by calculations of the energies of key intermediates and transition states.
- Begue, Didier,Dargelos, Alain,Berstermann, Hans M.,Netsch, Klaus P.,Bednarek, Pawel,Wentrup, Curt
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p. 1247 - 1253
(2014/03/21)
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- Study on the conversion of glycerol to nitriles over a Fe 19.2K0.2/γ-Al2O3 catalyst
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An Fe19.2K0.2/γ-Al2O3 catalyst for the catalytic amination of glycerol to propionitrile was prepared. Acetonitrile as a major product was obtained over this catalyst from the amination of glycerol. Additionally, propionitrile, ethylene and propylene were also obtained. The parameters influencing the catalyst performance were studied thoroughly, and an optimised process for the amination of glycerol to acetonitrile and propionitrile over the catalyst was obtained. Under the optimised conditions, which were a reaction temperature of 525 °C, an atmospheric pressure with an ammonia/glycerol molar ratio of 8:1 and GHSV of 1338 h-1, the total yield of acetonitrile and propionitrile was 58.4%, and the converted amount of glycerol over one gram of catalyst reached 0.42 g h-1. The catalyst was characterised by XRD, XPS, TEM and IR of the adsorbed pyridine. The characterisation results indicated that the dehydration reaction in the tandem reaction mainly occurred on the Lewis acid sites and revealed that both Fe2O3 and Fe 3O4 are active species for the dehydrogenation of imines to nitriles, but the former is more active than the latter. It also revealed that the catalyst deactivation was due to carbon deposits, the transformation of Fe2O3 to the Fe3O4 phase, as well as agglomeration of the Fe2O3 or Fe3O 4 phase during the catalytic run and regeneration process.
- Zhang, Yuecheng,Ma, Tianqi,Zhao, Jiquan
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- Facile access to 3,5-symmetrically disubstituted 1,2,4-thiadiazoles through phosphovanadomolybdic acid catalyzed aerobic oxidative dimerization of primary thioamides
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In the presence of Keggin-type phosphovanadomolybdic acids, e.g., H 6PV3Mo9O40, oxidative dimerization of various kinds of primary thioamides including aromatic, heterocyclic, and aliphatic ones efficiently proceeded to give the corresponding 3,5-disubstituted 1,2,4-thiadiazoles in excellent yields. This journal is the Partner Organisations 2014.
- Yajima, Kazuhisa,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 6748 - 6750
(2014/06/23)
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- METHOD FOR PREPARATION OF ACETONITRILE FROM ETHANOL AND AMMONIA BY AMINATION-DEHYDROGENATION
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The invention discloses a method for preparation of acetonitrile from ethanol and ammonia by amination-dehydrogenation using cobalt oxide supported on SiO2 as catalyst.
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Page/Page column 14-18
(2014/10/03)
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- Phenyliodonium diacetate mediated direct synthesis of benzonitriles from styrenes through oxidative cleavage of C=C bonds
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A metal-free PhI(OAc)2 mediated nitrogenation of alkenes through C=C bond cleavage using inorganic ammonia salt as nitrogen source under mild conditions was developed, affording nitriles in moderate to good yields. The advantages of this reaction are mild reaction conditions, operational simplicity, and use of an ammonium salt as nitrogen source. Based upon experimental observations, a plausible reaction mechanism is proposed.
- Xu, Jin-Hui,Jiang, Qing,Guo, Can-Cheng
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p. 11881 - 11886
(2014/01/06)
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- An alternative pathway for production of acetonitrile: Ruthenium catalysed aerobic dehydrogenation of ethylamine
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The oxidative synthesis of acetonitrile from ethylamine was studied using a supported ruthenium catalyst. The reaction was conducted in both batch and flow processes and high conversions (over 85%) were achieved in both cases. Selectivity of both reactions was improved by optimisation of reaction conditions, achieving over 90% selectivity in the batch process and 80% selectivity in the continuous flow process. The use of a selective solid catalyst that utilises a feedstock that can be derived from biomass, dioxygen as the oxidant and water as the solvent represents a new, green route for the independent and efficient production of acetonitrile.
- Corker, Emily C.,Mentzel, Uffe V.,Mielby, Jerrik,Riisager, Anders,Fehrmann, Rasmus
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p. 928 - 933
(2013/07/26)
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- Molecular products from the thermal degradation of glutamic acid
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The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid.
- Kibet, Joshua K.,Khachatryan, Lavrent,Dellinger, Barry
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p. 7696 - 7704
(2013/09/02)
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- Amination of allyl alcohol to propionitrile over a Zn30Cr 4.5/γ-Al2O3 bimetallic catalyst via coupled dehydrogenation-hydrogenation reactions
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A Zn30Cr4.5/γ-Al2O3 bimetallic catalyst that can perform coupled dehydrogenation and hydrogenation reactions was prepared for the amination of allyl alcohol to propionitrile. During the catalysis, the hydrogen derived from the dehydrogenation of the alcohol and imine acted as an in situ source for the hydrogenation of the carbon-carbon double bond. The catalyst exhibited good performance for the reaction at atmospheric ammonia pressure. The parameters that affect the catalyst performance were studied thoroughly, and an optimized process for synthesizing propionitrile from allyl alcohol and ammonia over the catalyst was obtained. Under the optimized conditions, the propionitrile yield was greater than 65%. The characterization results indicated that the dehydrogenation reaction mainly occurred on the Lewis acid sites and revealed that ZnAl 2O4 is the active species for the coupled dehydrogenation-hydrogenation reactions. Chromium doping of the γ-Al 2O3-supported zinc catalyst Zn30/γ- Al2O3 resulted in a decrease in the size of the ZnAl 2O4 crystallites, which was favorable for the dehydrogenation-hydrogenation reactions. The characterization results also revealed that the catalyst deactivation was due to carbon deposition on the catalyst during the catalytic run. The catalyst could be reactivated by blowing air into the reactor at a high temperature.
- Zhang, Yuecheng,Wei, Tianyu,Pian, Yanjie,Zhao, Jiquan
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p. 154 - 162
(2013/09/02)
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- Highly active and selective supported bulk nanostructured MoVNbTeO catalysts for the propane ammoxidation process
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We report a methodology to prepare nanoscaled supported-bulk MoVNbTeO catalysts in which the phases required to obtain an active and selective catalysts are nanoscaled on the surface of a support. Thus, a more economic catalytic material with improved mechanical properties can be obtained. The effect of vanadium content and atmosphere of calcination on the catalytic performance are discussed, and the results of the supported-catalysts are compared with those of bulk catalytic samples, which have been prepared as reference. The best supported catalyst afford ca. 50% acrylonitrile yield with 80% propane conversion at 450 °C. The activity per gram of MoVNbTeO increases fourfold upon stabilization of its nanoparticles.
- Lopez-Medina, R.,Rojas, E.,Banares, M. A.,Guerrero-Perez, M. O.
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p. 67 - 71,5
(2020/08/20)
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- Thermolytic synthesis of graphitic boron carbon nitride from an ionic liquid precursor: Mechanism, structure analysis and electronic properties
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Recent work has shown the potential of ionic liquids (ILs) as a precursor for porous networks and nitrogen doped carbon materials. The combination of liquid state and negligible vapour pressure represents almost ideal precursor properties and simplifies the processing drastically. Here, we extend this work to get a deeper insight into the solid formation mechanism and to synthesize a mixed boron carbon nitride species by the thermolysis of N,N′- ethylmethylimidazolium tetracyanoborate (EMIM-TCB), a well-known boron- and nitrogen-containing IL. In contrast to other molecule pyrolysis routes boron carbon nitride shows the average composition BC3N and like other IL-derived materials turns out to be distorted graphitic, but thermally and chemically very stable, and possesses favourable electrical properties. The detailed mechanistic investigation using TG-IR, FT-IR, solid-state NMR, Raman, WAXS, EELS, XPS and HRTEM also contributes to the general understanding of IL-based material formation mechanisms. The Royal Society of Chemistry 2012.
- Fellinger, Tim-Patrick,Su, Dang Sheng,Engenhorst, Markus,Gautam, Devendraprakash,Schloegl, Robert,Antonietti, Markus
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p. 23996 - 24005
(2013/01/15)
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- Thermolysis and photolysis of N-benzoylhydrazone derivatives
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Two selected N-benzoylhydrazones were subjected to thermolysis by refluxing at 200 °C. Benzil, benzoic acid, biphenyl, benzanilide together with the corresponding ketones, nitriles, substituted methanes, and imines were isolated. Similar treatment of a third hydrazone at 250 °C afforded, in addition to the previous products, toluene, bibenzyl, stilbene, and 2-phenylindole. Photolysis of the same hydrazones in acetonitrile gave the previously reported products but in different ratios along with azine derivatives and substituted methanes. A free radical mechanism involving homolysis of the N-N and C-N bonds is suggested, substantiated by trapping of the phenyl radical with isoquinoline, to account for the formation of the identified products.
- Gaber, Abd El-Aal M.,Khairou, Khalid S.
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experimental part
p. 1021 - 1027
(2012/07/27)
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- The pyrolysis of isoxazole revisited: A new primary product and the pivotal role of the vinylnitrene. A low-temperature matrix isolation and computational study
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This paper describes the pyrolysis of parent isoxazole and of its 5-methyl and 3,5-dimethyl derivatives by the high-pressure pulsed pyrolysis method, where activation of the precursor molecules occurs predominantly by collisions with the host gas (Ar in our case), rather than with the walls of the pyrolysis tube, where catalyzed processes may occur. The products were trapped at 15 K in Ar matrices and were characterized by vibrational spectroscopy. Thereby, hitherto unobserved primary products of pyrolysis of isoxazole and of its 5-methyl derivative, 3-hydroxypropenenitrile or 3-hydroxybutenenitrile, respectively, were observed. E-Z photoisomerization could be induced in the above hydroxynitriles. On pyrolysis of isoxazole, ketenimine and CO were observed as decomposition products, but this process did not occur when the 5-methyl derivative was pyrolyzed. Instead, the corresponding ketonitrile was formed. In the case of 3,5-dimethylisoxazole, 2-acetyl-3-methyl-2H-azirine was detected at moderate pyrolysis temperatures, whereas at higher temperatures, 2,5-dimethyloxazole was the only observed rearrangement product (next to products of dissociation). These findings are rationalized on the basis of quantum chemical calculations. Thereby it becomes evident that carbonyl-vinylnitrenes play a pivotal role in the observed rearrangements, a role that had not been recognized in previous theoretical studies because it had been assumed that vinylnitrenes are closed-shell singlet species, whereas they are in fact open-shell singlet biradicaloids. Thus, the primary processes had to be modeled by the multiconfigurational CASSCF method, followed by single-point MR-CISD calculations. The picture that emerges from these calculations is in excellent accord with the experimental findings; that is, they explain why some possible products are observed while others are not.
- Nunes, Claudio M.,Reva, Igor,Pinho E Melo, Teresa M. V. D.,Fausto, Rui,Solomek, Tomas,Bally, Thomas
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supporting information; experimental part
p. 18911 - 18923
(2012/02/05)
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- Vapor-phase Beckmann rearrangement of cyclohexanone oxime over halide cluster catalysts
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When a silica gel-supported tungsten halide cluster with an octahedral metal framework, (H3O)2[(W6Cl 8)Cl6]·6H2O/SiO2, is treated in a helium stream in the temperature range 250-350 °C, catalytic activity for the Beckmann rearrangement of cyclohexanone oxime develops. Niobium and tantalum clusters with the same metal framework also catalyze the reaction. Cyclopentanone oxime and acetone oxime also undergo Beckmann rearrangements over the tungsten cluster. The weak Br?nsted acidity (H0 ≈ +1.5) of the hydroxo ligand, which is developed on the activated cluster, is favorable for the rearrangement.
- Nagashima, Sayoko,Kamiguchi, Satoshi,Ohguchi, Satoshi,Chihara, Teiji
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experimental part
p. 135 - 138
(2012/02/03)
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- HIGH-YIELD PRODUCTION OF ORGANIC NITRILES
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A process is disclosed for producing organic nitriles such as Acetonitrile or Hydrogen Cyanide, in which yields may exceed 90%, undesirable by-products are not produced, and handling of ammonia gas is avoided. In one aspect, a process includes preparing a feed including ammonium salts and water; introducing the feed into a reactor containing a catalyst; and heating the feed in the presence of the catalyst. The catalyst may advantageously include molybdenum on a silica or silica alumina support. The feed may be ammonium acetate in water with about 50 wt % ammonium acetate and the balance water or ammonium formate in water. In another aspect, a process includes preparing a feed including ammonium hydroxide and acetic acid; introducing the feed into a reactor containing a catalyst; and heating the feed in the presence of the catalyst.
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Page/Page column 2
(2011/06/19)
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- A mild and efficient rhenium-catalyzed transfer hydrogenation of terminal olefins using alcoholysis of amine-borane adducts as a reducing system
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[ReBr2(NO)(CH3CN)(PTA)2] (PTA = 1, 3, 5-triaza-7-phosphaadamantane) catalyzes the alcoholysis of ammonia-borane and amine-boranes and the catalytic transfer hydrogenations of various terminal olefins. Excellent yields were achieved at 70 °C in isopropanol using tBuOK as a co-catalyst affording TOF values up to 396 h-1.
- Dong, Hailin,Berke, Heinz
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experimental part
p. 1803 - 1808
(2011/06/19)
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- PROCESS FOR THE AMMOXIDATION OF PROPANE AND ISOBUTANE
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A process for the ammoxidation of a saturated or unsaturated hydrocarbon to form an unsaturated nitrile, the process including the steps of contacting the hydrocarbon with ammonia, an oxygen-containing gas, and steam, in the presence of a mixed oxide catalyst.
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Page/Page column 8
(2009/08/16)
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- Studies on the deamination of the ethyl ester of 5-amino-3-methylisoxazole- 4-carboxylic Acid
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The unusual behavior of the ethyl ester of 5-amino-3-methylisoxazole-4- carboxylic acid (1) during deamination is described. Possible explanations for the anomalies of the diazotization reaction are proposed. Deamination methods leading to ethyl ester of 3-methylisoxazole-4-carboxylic acid (5) are presented. 5 will serve as a lead compound for a new series of immunomodulatory agents.
- Ryng,Szostak
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scheme or table
p. 887 - 893
(2010/02/27)
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- PROCESS FOR THE AMMOXIDATION OR OXIDATION OF PROPANE AND ISOBUTANE
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A process for the ammoxidation or oxidation of a saturated or unsaturated or mixture of saturated and unsaturated hydrocarbon, the process including the steps of combining a performance modifier, a fresh mixed oxide catalyst, or a used mixed oxide catalyst and a fresh and used mixed oxide catalyst to form a catalyst mixture, and contacting the hydrocarbon with an oxygen-containing gas, or an oxygen-containing gas and ammonia, in the presence of the catalyst mixture. The performance modifier may include a compound selected from the group consisting of aluminum compounds, antimony compounds, arsenic compounds, boron compounds, cerium compounds, germanium compounds, lithium compounds, molybdenum compounds, neodymium compounds, niobium compounds, phosphorus compounds, selenium compounds, tantalum compounds, tellurium compounds, titanium compounds, tungsten compounds, vanadium compounds, zirconium compounds and mixtures thereof.
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Page/Page column 29
(2009/05/28)
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- Catalyst composition without antimony or molybdenum for ammoxidation of alkanes, a process of making and a process of using thereof
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Disclosed is a catalyst composition which does not contain antimony or molybdenum for the vapor phase ammoxidation of alkanes of the general empirical formula: [in-line-formulae]VWaBibMcOx[/in-line-formulae] wherein M is one or more elements selected from sodium, cesium, magnesium, calcium, barium, boron, yttrium, indium, aluminum, gallium, tin, titanium, silicon, zirconium, germanium, niobium and tantalum, a is 0.2 to 10, b is 0.5 to 5, c is 0 to 10 and x is determined by the valence requirements of the elements present. The catalyst precursor is precipitated from a solution or slurry of compounds of vanadium, tungsten, bismuth and, optionally, M, then separated, dried and calcined to give a phase or combination of phases active in the ammoxidation of low-weight paraffins to the corresponding unsaturated mononitriles. Nitriles may be produced in a gas phase catalytic reaction of alkanes with ammonia and oxygen in the presence of the catalyst.
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Page/Page column 5-6
(2008/06/13)
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- In situ modification of molybdenum-based catalysts
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A process for the conversion of a hydrocarbon selected from the group consisting of propylene, isobutylene, propane, isobutane or mixtures thereof, to acrylonitrile, methacrylonitrile, or mixtures thereof, the process comprising the step of reacting in the vapor phase at an elevated temperature and pressure said hydrocarbon with a molecular oxygen-containing gas and ammonia, in the presence of a molybdenum-based ammoxidation catalyst and a catalyst modifier, wherein said catalyst modifier comprises a molybdate or a polymolybdate of at least one element M selected from the group consisting of cesium, rubidium, potassium, sodium, thallium, lithium, nickel, cobalt, iron, chromium, copper, magnesium, manganese, cerium and phosporus, and wherein the ratio of the M elements to Mo in the molybdate or polymolybdate is greater than the ratio for these M elements to Mo in the molybdenum-based catalyst. The catalyst modifier is useful in modifying the performance of molybdenum-based catalyst and inhibiting molybdenum oxide loss for such catalysts.
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Page/Page column 5-6
(2008/06/13)
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- New class of catalysts for the ammoxidation of propane to acrylonitrile over nickel-molybdenum mixed nitrides
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Nickel-molybdenum mixed nitride catalysts were first reported for the ammoxidation of propane to acrylonitrile. It was found that the mixed nitrides exhibited high activity and selectivity to acrylonitrile. The mixed nitride catalyst with 1.0 of Ni/Mo atomic ratios showed the best catalytic properties for propane ammoxidation. The highest yield of acrylonitrile was 28.5% at the propane conversion of 68.4% at 773 K. Copyright
- Zhang, Huimin,Zhao, Zhen,Xu, Chunming,Duan, Aijun
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- HIGH-PURITY ACETONITRILE AND PROCESS FOR PRODUCING THE SAME
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A process for producing high-purity acetonitrile having a low absorbance at a wavelength of 200 nm. It requires a reduced amount of energy for purification and the purification step is simple. It considerably diminishes the propionitrile contained in acetonitrile. The process for high-purity acetonitrile production is characterized by mixing hydrous crude acetonitrile with an alkali, separating the mixture into an acetonitrile phase and an aqueous phase, removing the aqueous phase, subjecting the resultant acetonitrile phase to a distillation step to obtain purified acetonitrile, and passing the resultant purified acetonitrile through an cation-exchange resin to obtain high-purity acetonitrile.
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Page/Page column 9-10
(2008/06/13)
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- PROCESS FOR THE PRODUCTION OF ACRYLONITRILE USING DIRECT CONTACT SPRAY HEAT EXCHANGE IN THE ABSORBER
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A process for manufacturing acrylonitrile comprising reacting propylene, ammonia and oxygen in a reactor zone in the presence of a catalyst to produce a reactor effluent containing crude acrylonitrile, transferring the reactor effluent containing crude acrylonitrile to a quench column wherein the reactor effluent containing crude acrylonitrile is contacted with an aqueous stream to cool the reactor effluent, transferring the cooled reactor effluent containing the crude acrylonitrile to an absorption column wherein the reactor effluent containing crude acrylonitrile is contacted with a second aqueous stream to separate and remove the crude acrylonitrile as a bottom stream from the absorption column, transferring the bottom stream containing the crude acrylonitrile to a recovery and purification section where the acrylonitrile is recovered and purified, wherein the improvement comprises supplying the second aqueous stream to the absorption column by means of liquid spray nozzles.
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Page column 3
(2008/06/13)
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- Ammoxidation of carboxylic acids to a mixture of nitriles
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A process for increasing the yield of acetonitrile produced during the manufacture of acrylonitrile comprising introducing a hydrocarbon selected from the group consisting of propylene and propane, a carboxylic acid, ammonia and air into a reaction zone containing an ammoxidation catalyst, reacting the hydrocarbon, carboxylic acid, ammonia and oxygen over said catalyst at an elevated temperature to produce acrylonitrile, hydrogen cyanide and acetonitrile, and recovering the acrylonitrile, hydrogen cyanide and acetonitrile from the reactor.
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Page/Page column 3-4
(2008/06/13)
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- High-Precision Position-Specific Isotope Analysis of 13C/ 12C in Leucine and Methionine Analogues
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We report an automated method for high-precision position-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 °C, the characteristic pyrolysis products for 3MTP were CH4, C 2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with >95% structural fidelity. Isotope ratios for the fragments were determined with an average precision of SD(δ13C) 13C) 13C values of fragments were invariant over a range of pyrolysis temperatures. The Δδ13C of complementary fragments in IAA was within 0.8‰ of the Δδ13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using Δδ 13C values of fragments, Δδ13C values were determined for all four carbon positions of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in position-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30‰ at C1, 48.33‰ at C2, 0.37‰ at C3, and 5.36‰ at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular isotope ratios due to natural processes.
- Sacks, Gavin L.,Brenna, J. Thomas
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p. 5495 - 5503
(2007/10/03)
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- Properties of mixed polyfunctional fluoride catalysts for synthesis of pyridine bases from acetylene and ammonia (methanol)
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New catalysts based on cadmium, zinc, chromium, iron, and aluminum compounds were synthesized and their properties were studied. A pilot catalyst batch was obtained and tested on a pilot installation.
- Khamidullaev,Yusupov
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p. 939 - 942
(2007/10/03)
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- Thermal decomposition and ring expansion in 2,4-dimethylpyrrole. Single pulse shock tube and modeling studies
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The thermal decomposition of 2,4-dimethylpyrrole was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 1050-1250 K at overall densities of ~3 × 10-5 mol/cm3. A plethora of decomposition products, both with and without nitrogen, were found in the post-shock mixtures. They were, among the nitrogen containing products: pyridine, two isomers of methylpyrrole, 2-picoline, 5-picoline, HCN, CH3CN, C2H3CN, C2H5CN, and CH≡C-CN. Very small quantities of cis- and trans-CH3CH=CHCN and CH2=CHCH2CN were also found in the post-shock mixtures. Among the products without nitrogen were CH4, C2H4, C2H6, C2H2, CH3H≡CH, CH2=C=CH2, C4H4 and C4H2, and very small quantities of other C4 hydrocarbons and C5 hydrocarbons. The initiation of a chain mechanism in the decomposition of 2,4-dimethylpyrrole takes place via ejection of hydrogen atoms from sp3 carbons and dissociation of the two methyl groups attached to the ring. The H atoms and the methyl radicals initiate a chain mechanism by abstraction of a hydrogen atom from the methyl group and by dissociative recombination of an H atom and removal of a methyl group from the ring. In addition to the dissociation reactions, there are several unimolecular channels that involve ring cleavage. Ring expansion processes that lead to the production of high yields of pyridine and picoline take place from radical species: CH3[C4H2NH]CH2 in the production of picoline and [C4H3NH]CH2 in the production of pyridine. In addition to the chain mechanism, there are unimolecular breakdown processes of the pyrrole ring to yield stable products such as HCN, CH3CN, and others. The total decomposition of 2,4-dimethylpyrrole in terms of a first-order rate constant is given by ktotal = 1016.31 exp(-75.7 × 103/RT) s-1. A reaction scheme containing 36 species and 69 elementary reactions was composed and a computer simulation was performed over the temperature range 1050-1250 K at 25 K intervals. The agreement between the experimental results and the model prediction for most of the species is satisfactory.
- Lifshitz, Assa,Suslensky, Aya,Tamburu, Carmen
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p. 4851 - 4861
(2007/10/03)
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- Thermodynamics of the donor-acceptor interaction of zinc(II)tetraphenylporphyrin with mono- and dinitriles
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Calorimetric titration was used for the first time to measure the thermodynamic characteristics of complexation of zinc(II) tetraphenylporphyrin with mono- and dinitriles. The effect of the electronic structure and the electron density distribution in the molecular ligands on the thermodynamic characteristics was examined. In passing from the benzene to the carbon tetrachloride solvent, both the exothermicity of the reactions under study and the stability of the complexes formed increase.
- Lebedeva,Mikhailovskii,V'yugin,Davydova
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p. 1028 - 1030
(2007/10/03)
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- Operando raman study of alumina-supported Sb-V-O catalyst during propane ammoxidation to acrylonitrile with on-line activity measurement
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Operando Raman spectra during propane ammoxidation show partially reversible structural transformations of the active phases as a function of reaction environment.
- Guerrero-Perez,Banares
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p. 1292 - 1293
(2007/10/03)
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- Synthesis and pyrolysis of tetrahydro-1,4-oxazine-3,5-diones and tetrahydro-1,4-thiazine-3,5-diones
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The preparation and characterization of six 4-substituted tetrahydro-l,4-oxazine-3,5-diones and five 4-substituted tetrahydro-l,4-thiazine-3,5-diones is described. Upon flash vacuum pyrolysis at 700°C these give N-substituted acetamides and nitriles, and a mechanism for formation of these products is proposed.
- Aitken,Farrell,Kirton
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p. 1526 - 1531
(2007/10/03)
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- Selective ammoxidation of isobutylene to methacrylonitrile on a new family of crystalline Re-Sb-O catalysts
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The catalytic properties of a new family of crystalline Re-Sb-O compounds SbRe2O6, SbOReO4·2H2O, and Sb4Re2O13 in selective ammoxidation of isobutylene to methacrylonitrile (MAN) have been studied and compared with those of a coprecipitated SbRe2Ox catalyst, an Sb2O3-supported Re2O7 catalyst, bulk Re oxides, and bulk Sb oxides. The Re-based catalysts were more or less active for MAN synthesis with selectivities of 47.9-83.6% at 673 K, whereas bulk Sb oxides (Sb2O3 and Sb2O4) showed no activity. The results demonstrate that Re is prerequisite for the ammoxidation catalysis of Re-Sb-O systems. In catalytic systems the presence of Sb also contributes to the ammoxidation catalysis for MAN synthesis. Among these catalysts, SbRe2O6 was most active and selective (83.6%) for MAN formation at 673 K. No structural change in the bulk and surface of SbRe2O6 was observed after i-C4H8 ammoxidation by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and confocal laser Raman microspectroscopy. The good performance of SbRe2O6 may be ascribed to its specific crystal structure composed of alternate octahedral (Re2O6)3- and (SbO)+ layers. Pulse reaction results suggested that adsorbed NH3 species on the SbRe2O6 catalyst facilitated the adsorption and subsequent activation of isobutylene. Increasing reaction temperature and decreasing GHSV did not give rise to increasing formation of by-products CO2 and acetonitrile, while increasing the i-C4H8 conversion. Thus the crystalline SbRe2O6 compound may be a new promising catalyst for ammoxidation of light hydrocarbons.
- Liu, Haichao,Imoto, Hideo,Shido, Takafumi,Iwasawa, Yasuhiro
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- Flash vacuum pyrolysis over solid catalysts. 1. Pyrazoles over zeolitest
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Flash vacuum pyrolysis (fvp) reactions of 1H-pyrazole (1), 3,5-dimethylpyrazole (2), and 3,5-diphenylpyrazole (3) were carried out over zeolites. Reactions were performed using ZCOY-7, NH4-Y, and Na-Y zeolites. Reaction temperatures of heterogeneous reactions were lower than the corresponding temperatures in the homogeneous system, showing a catalytic effect of the zeolites. Compounds 1-3 afforded nitrogen extrusion in homogeneous fvp reactions while in the heterogeneous ones different reactions were present. Compounds 1 and 2 also afforded nitrogen extrusion; products arising from ring fragmentation were found in reactions of 2 and 3 while an isomeric imidazole was isolated in reactions of 3. Isomerization of 3 is attributed to a transition-state selectivity by the catalyst due to the relation between the size of the molecule and the cavity of the zeolite. This isomerization reaction was present only when zeolites with active Broensted sites were used.
- Moyano,Yranzo
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p. 2943 - 2947
(2007/10/03)
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- Thermal decomposition of 4-methylpyrimidine. Experimental results and kinetic modeling
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The decomposition of 4-methylpyrimidine was studied behind reflected shock waves in a pressurized driver single-pulse shock tube at 1160-1330 K and overall densities of ~ 3 × 10-5 mole/cc. A plethora of decomposition products, both with and without nitrogen, (HCN, CH3CN, C2H3CN, CH4, C2H6, C2H4, etc.) was found in the post-shock mixtures. The attack of methyl radicals on the methyl group in 4-methylpyrimidine produced CH4, which was a major product among the species not containing nitrogen, leaving the radical 4-methylene pyrimidyl. The H atoms and methyl radicals initiated a chain mechanism by abstraction of an H atom from the methyl group and by dissociative attachment of an H atom and removal of a methyl group from the ring. The decomposition mechanism was discussed.
- Lifshitz, Assa,Suslensky, Aya,Tamburu, Carmen
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p. 3542 - 3554
(2007/10/03)
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- Pyrolysis nozzles coupled to a microwave spectrometer with stark modulation for the detection of transients species in a supersonic expansion
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Two types of pyrolysis nozzles have been constructed and coupled to a new Stark modulated microwave spectrometer. The nozzles were tested on their ability to generate rotationally cooled transient species through a supersonic expansion. The transients species vinylamine, thioketene and ketene were generated and detected using nozzle temperatures ranging from 400-800°C. Pyrolysis temperatures were generally lower than those used in normal flow pyrolysis experiments and rotational temperatures of ca. 10 K were achieved. A preliminary investigation of the jet nozzle pyrolysis of 3-methyl-4-hydroxyiminoisoxaline-5-one was carried out and showed a different distribution of CHNO pyrolysis products to that observed in previous low pressure studies. by Oldenbourg Wissenschaftsverlag, Muenchen.
- McNaughton, Don,Evans, Corey J.
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p. 1313 - 1327
(2007/10/03)
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- Selective ammoxidation of isobutane on a crystalline SbRe2O6 catalyst
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The catalytic ammoxidation of isobutane to methacrylonitrile at 673 K proceeds on a new class of Re mixed-oxide SbRe2O6 with alternate (Re2O6)3- and (SbO)+ layers, where ammonia is prerequisite for the C-H bond scission of isobutane.
- Liu,Shido,Iwasawa
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p. 1881 - 1882
(2007/10/03)
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