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Isomerization of Allene Propyne in Shock Waves and ab Initio Calculations
The isomerization allene propyne has been studied behind shock waves over the temperature range between 1300 and 2100 K and the total density range of (0.6-2.4) x 1E-5 mol/cm3.The isomerization rate was monitoring by means of the IR emission from allene and propyne.It was found that the process proceeded in the fall-off region, and the high-pressure limit rate constants were determined as k1 = 1E14.34 exp-1/(RT)> s-1, for the isomerization of allene to propyne, and k-1 = 1E14.14 exp-1/(RT)> s-1, for the isomerization of propyne to allene, using the equilibrium constants.Ab initio molecular orbital calculations have also been performed for the isomerization.It was found that the isomerization proceeded in a series of successive reactions via cyclopropene, which has been suggested by Honjou et al. (Honjou, N.; Pacansky, J.; Yoshimine, M.J.Am.Chem.Soc. 1984, 106, 5361).The rate constants estimated in terms of the transition-state theory, k1 = 1E14.23 exp-1/(RT)> s-1 and k-1 = 1E14.12 exp-1/(RT)> s-1, are consistent with the experimental results.
Kakumoto, Terumitsu,Ushirogouchi, Toshiaki,Saito, Ko,Imamura, Akira
p. 183 - 189
(1987)
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The isotope exchange reaction of fast hydrogen atoms with deuterated alkynes and alkenes
The exchange reaction H (1 eV) + RD -> RH + D, where RD was deuterated acetylene, methylacetylene, ethylene, and propylene was studied by laser induced fluorescence detection of the hydrogen and deuterium atoms.The reaction cross sections were 1.69 +/- 0.
Johnston, Grace W.,Satyapal, Sunita,Bersohn, Richard,Katz, Benjamin
p. 206 - 212
(1990)
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Novel tocopherol compounds IV. 5-tocopherylacetic acid and its derivatives
A new class of tocopherol (vitamin E) compounds, 5-tocopherylacetic acid derivatives, is presented. The synthesis and some unexpected properties of these compounds, such as relatively high thermal and chemical stability, are described and discussed in comparison with the labile 5a-halogeno-, 5a-alkoxy- or 5a-amino-substituted tocopherols.
Rosenau, Thomas,Habicher, Wolf Dieter,Chen, Chen-Loung
p. 787 - 798
(1996)
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Rearrangement of a Metal (η2-Alkyne) Complex to a Metal Vinylidene and Subsequent Reaction of the Metal Vinylidene to Regenerate the Alkyne
The η2-alkyne complex (C5H5)(PMe3)2Ru(HC(*)CMe)+PF6-, which was isolated from a reaction of HC(*)CMe with (C5H5)(PMe3)2RuCl, undergoes first-order rearrangement to give (C5H5)(PMe3)2Ru=C=C(H)Me+PF6-;
Bullock, R. Morris
p. 165 - 167
(1989)
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Kinetics of thermal gas-phase decomposition of 2-bromopropene using static system
The gas phase elimination kinetics of 2-bromopropene was studied over the temperature range of 571-654 K and pressure range of 12-46 Torr using the seasoned static reaction system. Propyne was the only olefinic product formed and accounted for >98% of the reaction. This product was formed by homogeneous, unimolecular pathways with high-pressure first-order rate constant k∞ given by the equation k∞ = 10 13.47±0.6 exp-208.2±6.7(kj mol-1)/RT. The error limits are 95% certainty limits. The observed Arrhenius parameters are consistent with the four centered activated complex. The presence of methyl group on α-carbon lowers the activation energy by 41 kj mol-1.
Nisar, Jan,Awan, Iftikhar A.
p. 1 - 5
(2007)
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Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled
Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we use operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C2+ radical intermediates participating in the complex gas-phase reaction network. Our experiments pinpoint different C2-C5 radical species that allow for a stepwise growth of the hydrocarbon chains. Propargyl radicals (H2C?C≡C?H) are identified as essential precursors for the formation of aromatics, which then contribute to the formation of heavier hydrocarbon products via hydrogen abstraction–acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for the development of methane valorization processes.
?ot, Petr,Hemberger, Patrick,Pan, Zeyou,Paunovi?, Vladimir,Puente-Urbina, Allen,van Bokhoven, Jeroen Anton
supporting information
p. 24002 - 24007
(2021/10/01)

Synthesis of Cyclopentenones with Reverse Pauson-Khand Regiocontrol via Ni-Catalyzed C-C Activation of Cyclopropanone
A formal [3 + 2] cycloaddition between cyclopropanone and alkynes via Ni-catalyzed C-C bond activation has been developed, where 1-sulfonylcyclopropanols are employed as key precursors of cyclopropanone in the presence of trimethylaluminum. The transformation provides access to 2,3-disubstituted cyclopentenones with complete regiocontrol, favoring reverse Pauson-Khand products, where the large substituent is located at the 3-position of the ring. In the process, the trimethylaluminum additive is thought to play multiple roles, including as a Br?nsted base triggering the equilibration to cyclopropanone and liberation of methane, as well as a source of Lewis acid to activate the carbonyl group toward Ni-catalyzed C-C activation.
Jang, Yujin,Lindsay, Vincent N. G.
supporting information
p. 8872 - 8876
(2020/12/02)

METHOD FOR PREPARATION OF NANOCERIA SUPPORTED ATOMIC NOBLE METAL CATALYSTS AND THE APPLICATION OF PLATINUM SINGLE ATOM CATALYSTS FOR DIRECT METHANE CONVERSION
Described are methods for converting methane to olefins, aromatics, or a combination thereof using a single atom catalyst comprising CeO2 nanoparticles impregnated with individual atoms of noble metals including Pt, Pd, Rh, Ru, Ag, Au, Ir, or a combination thereof. These single atom catalysts of the present invention are heated with methane to form olefins and aromatics.
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(2019/09/12)

Synthetic Studies Toward the Skyllamycins: Total Synthesis and Generation of Simplified Analogues
Herein, we report our synthetic studies toward the skyllamycins, a highly modified class of nonribosomal peptide natural products which contain a number of interesting structural features, including the extremely rare α-OH-glycine residue. Before embarking on the synthesis of the natural products, we prepared four structurally simpler analogues. Access to both the analogues and the natural products first required the synthesis of a number of nonproteinogenic amino acids, including three β-OH amino acids that were accessed from the convenient chiral precursor Garner's aldehyde. Following the preparation of the suitably protected nonproteinogenic amino acids, the skyllamycin analogues were assembled using a solid-phase synthetic route followed by a final stage solution-phase cyclization reaction. To access the natural products (skyllamycins A-C) the synthetic route used for the analogues was modified. Specifically, linear peptide precursors containing a C-terminal amide were synthesized via solid-phase peptide synthesis. After cleavage from the resin the N-terminal serine residue was oxidatively cleaved to a glyoxyamide moiety. The target natural products, skyllamycins A-C, were successfully prepared via a final step cyclization with concomitant formation of the unusual α-OH-glycine residue. Purification and spectroscopic comparison to the authentic isolated material confirmed the identity of the synthetic natural products.
Giltrap, Andrew M.,Haeckl, F. P. Jake,Kurita, Kenji L.,Linington, Roger G.,Payne, Richard J.
p. 7250 - 7270
(2018/06/01)

METHOD FOR PRODUCING ACETYLENE COMPOUND
PROBLEM TO BE SOLVED: To provide a method for producing an acetylene compound. SOLUTION: A method for producing an acetylene compound comprises a first step of obtaining a cesium compound-supported alumina catalyst by burning a solid that is obtained by supporting a cesium compound on an alumina carrier at 150-400°C, and a second step of isomerizing an allene compound in the presence of the catalyst obtained in the first step. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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(2017/02/23)

An acelylenically of a diene compound and/or method of manufacturing
Provided is a novel method for producing a compound having acetylene bonds and/or a diene. The method for producing a compound having acetylene bonds and/or a diene is characterized in that at least one selected from the group consisting of ketone compound (I), ketone compound (II), aldehyde compound (III), aldehyde compound (IV), and aldehyde compound (V) is dehydrated in the presence of a catalyst wherein a carrier containing silica supports at least one selected from the group consisting of compounds containing group 1 metal elements, compounds containing group 2 metal elements, group 1 metal elements, and group 2 metal elements.
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(2017/03/28)

Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene
The thermal decomposition of cyclopentene was studied in a jet-stirred reactor operated at constant pressure and temperature to provide new experimental information about the formation of the first aromatic rings from cyclic C5 species. Experim
Herbinet, Olivier,Rodriguez, Anne,Husson, Benoit,Battin-Leclerc, Frédérique,Wang, Zhandong,Cheng, Zhanjun,Qi, Fei
p. 668 - 682
(2016/02/23)

Synthesis of 1-Substituted Isoquinolines by Heterocyclization of TosMIC Derivatives: Total Synthesis of Cassiarin A
A new method for the synthesis of 1-substituted isoquinolines by a heterocyclization that involves α-benzyl TosMIC derivatives and different electrophiles has been developed. This methodology has been successfully applied to a total synthesis of cassiarin A, an alkaloid with potent antiplasmodial activity against Plasmodium falciparum.
Gutiérrez, Sara,Coppola, Anna,Sucunza, David,Burgos, Carolina,Vaquero, Juan J.
supporting information
p. 3378 - 3381
(2016/07/26)

Lanthanide-Catalyzed Reversible Alkynyl Exchange by Carbon–Carbon Single-Bond Cleavage Assisted by a Secondary Amino Group
Lanthanide-catalyzed alkynyl exchange through C?C single-bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β-alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo- and cross-dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions.
Shao, Yinlin,Zhang, Fangjun,Zhang, Jie,Zhou, Xigeng
supporting information
p. 11485 - 11489
(2016/10/24)

Tandem Claisen Rearrangement/6-endo Cyclization Approach to Allylated and Prenylated Chromones
Allyl, dimethylallyl and prenyl ethers derived from o-acylphenols reacted upon microwave irradiation to form C-allylated or -prenylated chromone derivatives, depending on the substitution pattern of the arene and the allyl substituent. The reaction proceeds through a tandem Claisen rearrangement and 6-endo-trig or 6-endo-dig cyclization sequence. For prenyl ethers, the tandem sequence can be extended by a Cope rearrangement to furnish 6-prenylchromones. The method is potentially useful for the synthesis of natural products and drugs.
Schmidt, Bernd,Riemer, Martin,Schilde, Uwe
supporting information
p. 7602 - 7611
(2016/01/25)

METHOD FOR PRODUCING METHACRYLIC ACID ESTER
The method for producing a methacrylic acid ester of the present invention comprises a dehydration reaction step of having acetone undergo a dehydration reaction in the presence of a dehydration reaction catalyst to obtain a reaction mixture; a propyne/propadiene separation step of separating a mixture containing propyne and propadiene as main components from the obtained reaction mixture; a propyne purification step of separating the separated mixture containing propyne and propadiene as main components into a liquid, gas, or gas-liquid mixture containing propyne as a main component, and a liquid, gas, or gas-liquid mixture containing propadiene as a main component; and a carbonylation reaction step of bringing the obtained liquid, gas, or gas-liquid mixture containing propyne as a main component into contact with carbon monoxide and an alcohol having 1 to 3 carbon atoms in the presence of a catalyst containing at least one selected from the group consisting of Group 8 metal elements, Group 9 metal elements, and Group 10 metal elements to obtain a methacrylic acid ester. According to the method of the present invention, it is possible to provide a method for producing a methacrylic acid ester, which is less likely to receive location restrictions and is also economically and industrially advantageous.
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(2016/01/25)

METHOD FOR PRODUCING COMPOUND AND/OR DIENE HAVING ACETYLENE BOND
PROBLEM TO BE SOLVED: To provide a method for producing a compound and/or diene having an acetylene bond at high productivity over a long period. SOLUTION: Provided is a method for producing a compound and/or diene having an acetylene bond characterized in that 1) a ketone compound is brought into dehydration reaction in the presence of a catalyst obtained by carrying (A) at least one kind of element selected from the group consisting of the first group elements and the second group elements and at least one kind of element (B) selected from the group consisting of the third group elements, the fourth group elements and the thirteenth elements into a carrier, and also provided the catalyst. COPYRIGHT: (C)2016,JPOandINPIT
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(2016/10/07)

METHOD OF PRODUCING METHYLACETYLENE
PROBLEM TO BE SOLVED: To provide a method of producing methylacetylene which achieves a higher yield. SOLUTION: Methylacetylene is synthesized from 2-chloroethanol and/or a vinyl chloride monomer by a solid acid catalytic reaction using an H type zeolite having a 12-membered-ring or higher pore size and a super-cage. COPYRIGHT: (C)2015,JPOandINPIT
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(2017/01/02)

Selenium- and tellurium-containing binucleophiles in selective synthesis of allene and methylacetylene from 2,3-dichloro-1-propene
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Levanova,Vakhrina,Grabel'Nykh,Russavskaya,Albanov,Rozentsveig,Korchevin
p. 164 - 165
(2014/03/21)

Reaction of diphenyl ditelluride with 2,3-dichloroprop-1-ene in the system hydrazine hydrate-KOH
Diphenyl ditelluride reacts with 2,3-dichloroprop-1-ene in the system hydrazine hydrate-KOH along several parallel routes. Beside the nucleophilic chlorine substitution at the sp 3-hybridized carbon atom resulting in 2-chloro-3-phenyltellanylprop-1-ene the elimination of both chlorine atoms occurs affording a mixture of allene and methylacetylene. The reasons of the dual elimination reaction paths are considered.
Levanova,Vakhrina,Grabel'Nykh,Rozentsveig,Russavskaya,Albanov,Korchevin
p. 175 - 178
(2014/04/17)

Direct, nonoxidative conversion of methane to ethylene, aromatics, and hydrogen
The efficient use of natural gas will require catalysts that can activate the first C-H bond of methane while suppressing complete dehydrogenation and avoiding overoxidation. We report that single iron sites embedded in a silica matrix enable direct, nonoxidative conversion of methane, exclusively to ethylene and aromatics. The reaction is initiated by catalytic generation of methyl radicals, followed by a series of gas-phase reactions. The absence of adjacent iron sites prevents catalytic C-C coupling, further oligomerization, and hence, coke deposition. At 1363 kelvin, methane conversion reached a maximum at 48.1% and ethylene selectivity peaked at 48.4%, whereas the total hydrocarbon selectivity exceeded 99%, representing an atom-economical transformation process of methane. The lattice-confined single iron sites delivered stable performance, with no deactivation observed during a 60-hour test.
Guo, Xiaoguang,Fang, Guangzong,Li, Gang,Ma, Hao,Fan, Hongjun,Yu, Liang,Ma, Chao,Wu, Xing,Deng, Dehui,Wei, Mingming,Tan, Dali,Si, Rui,Zhang, Shuo,Li, Jianqi,Sun, Litao,Tang, Zichao,Pan, Xiulian,Bao, Xinhe
p. 616 - 619
(2014/05/20)

Experimental investigation of the low temperature oxidation of the five isomers of hexane
The low-temperature oxidation of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethylbutane, and 2,3-dimethylbutane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric conditions between 550 and 1000 K. The evolution of reactant and product mole fraction profiles were recorded as a function of the temperature using two analytical methods: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental data obtained with both methods were in good agreement for the five fuels. These data were used to compare the reactivity and the nature of the reaction products and their distribution. At low temperature (below 800 K), n-hexane was the most reactive isomer. The two methyl-pentane isomers have about the same reactivity, which was lower than that of n-hexane. 2,2-Dimethylbutane was less reactive than the two methyl-pentane isomers, and 2,3-dimethylbutane was the least reactive isomer. These observations are in good agreement with research octane numbers given in the literature. Cyclic ethers with rings including 3, 4, 5, and 6 atoms have been identified and quantified for the five fuels. While the cyclic ether distribution was notably more detailed than in other literature of JSR studies of branched alkane oxidation, some oxiranes were missing among the cyclic ethers expected from methyl-pentanes. Using SVUV-PIMS, the formation of C 2-C3 monocarboxylic acids, ketohydroperoxides, and species with two carbonyl groups have also been observed, supporting their possible formation from branched reactants. This is in line with what was previously experimentally demonstrated from linear fuels. Possible structures and ways of decomposition of the most probable ketohydroperoxides were discussed. Above 800 K, all five isomers have about the same reactivity, with a larger formation from branched alkanes of some unsaturated species, such as allene and propyne, which are known to be soot precursors.
Wang, Zhandong,Herbinet, Olivier,Cheng, Zhanjun,Husson, Benoit,Fournet, Rene,Qi, Fei,Battin-Leclerc, Frederique
p. 5573 - 5594
(2014/08/18)

Metal ions do not play a direct role in the formation of carbon-carbon triple bonds during reduction of trihaloalkyls by CrII or V II
Carbyne radicals: Reactions of trihaloalkyl compounds with Cr2+ or V2+ in aqueous solutions yield alkynes and other products. Stepwise halogen abstractions from the trihaloalkyls form alkyl carbyne triradicals in solution. These radicals undergo coupling reactions, producing triply bonded alkyne molecules (see scheme). This process is not metal-assisted and does not occur in the coordination sphere of the metal ions.
Levy, Ophir,Bino, Avi
supporting information
p. 15944 - 15947
(2013/02/23)

UV laser photodeposition of nanomagnetic soot from gaseous benzene and acetonitrile-benzene mixture
Megawatt KrF laser gas-phase photolysis of benzene and acetonitrile-benzene mixture was studied by using mass spectroscopy-gas-chromatography and Fourier transform infrared spectroscopy for analyses of volatile products, and by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, electron microscopy and magnetization measurements for analyses of solid products deposited from the gas-phase. The results are consistent with carbonization of benzene and decomposition of non-absorbing acetonitrile in carbonizing benzene through collisions with excited benzene and/or its fragments. The solid products from benzene and acetonitrile-benzene mixture have large surface area and are characterized as nanomagnetic amorphous carbonaceous soot containing unsaturated C centers prone to oxidation. The nanosoot from acetonitrile-benzene mixture incorporates CN groups, confirms reactions of benzene fragments with CN radical and has a potential for modification by reactions at the CN bonds.
Pola, Josef,Ouchi, Akihiko,Mary?ko,Vorlí?ek,?ubrt, Jan,Bakardjieva,Bastl, Zdeněk
experimental part
p. 188 - 194
(2012/02/02)

Study of the catalytic dehydrochlorination of 1,2-dichloropropane
Catalytic dehydrochlorination of 1,2-dichloropropane in the presence of γ-Al2O3, CaX, and haydite was studied. A relationship between the catalytic activity and acidity of the catalysts under study was revealed.
Nadzhafov, Dzh Yu
scheme or table
p. 1532 - 1540
(2012/01/14)

GASEOUS DIELECTRICS WITH LOW GLOBAL WARMING POTENTIALS
A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about ?20° C. to about ?273° C.; non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL; and a dielectric strength greater than air.
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(2010/12/31)

Synthesis and structure-activity relationships of cassiarin A as potential antimalarials with vasorelaxant activity
Cassiarin A 1, a tricyclic alkaloid, isolated from the leaves of Cassia siamea (Leguminosae), shows powerful antimalarial activity against Plasmodium falciparum in vitro as well as P. berghei in vivo, which may be valuable leads for novel antimalarials. Interactions of parasitized red blood cells (pRBCs) with endothelium in aorta are especially important in the processes contribute to the pathogenesis of severe malaria. Nitric oxide (NO) reduces endothelial expression of receptors/adhesion molecules used by pRBC to adhere to vascular endothelium, and reduces cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 showed vasorelaxation activity against rat aortic ring, which may be related with NO production. A series of a hydroxyl and a nitrogen-substituted derivatives and a dehydroxy derivative of 1 have been synthesized as having potent antimalarials against P. falciparum with vasodilator activity, which may reduce cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 exhibited a potent antimalarial activity and a high selectivity index in vitro, suggesting that the presence of a hydroxyl and a nitrogen atom without any substituents may be important to show antimalarial activity. Relative to cassiarin A, a methoxy derivative showed more potent vasorelaxant activity, although it did not show improvement for inhibition of P. falciparum in vitro. These cassiarin derivatives may be promising candidates as antimalarials with different mode of actions.
Morita, Hiroshi,Tomizawa, Yuichiro,Deguchi, Jun,Ishikawa, Tokio,Arai, Hiroko,Zaima, Kazumasa,Hosoya, Takahiro,Hirasawa, Yusuke,Matsumoto, Takayuki,Kamata, Katsuo,Ekasari, Wiwied,Widyawaruyanti, Aty,Wahyuni, Tutik Sri,Zaini, Noor Cholies,Honda, Toshio
experimental part
p. 8234 - 8240
(2010/03/25)

Cyclic versus linear isomers produced by reaction of the methylidyne radical (CH) with small unsaturated hydrocarbons
The reactions of the methylidyne radical (CH) with ethylene, acetylene, allene, and methylacety- lene are studied at room temperature using tunable vacuum ultraviolet (VUV) photoionization and time- resolved mass spectrometry. The CH radicals are prepared by 248 nm multiphoton photolysisof CHBr 3 at 298 K and react with the selected hydrocarbon i n a helium gas flow. Analysis of photoionization efficiency versus VUV photon wavelength permits isomer-specific detection of the reaction products and allows estimation of the reaction product branching ratios. The reactions proceed by either CH insertion or addition followed by H atom elimination from the intermediate adduct. In the CH + C 2 H 4 reaction the C 3 H 5 intermediate decays byH atom loss to yield 70(±8)percent allene, 30(±8)percent methylacetylene, and less than 10percent cyclopropene, in agreement with previous RRKM results. In the CH + acetylene reaction, detection of mai nly the cyclic C 3 H 2 isomer is contrary to a previous RRKM calculations that predicted linear triplet propargylene to be 90percent of the total H-atom coproducts. High-level CBS-APNO quantum calculations and RRKM calculations for the CH + C 2 H 2 reaction presented in this manuscript predict a higher contribution of the cyclic C 3 H 2 (27.0percent) versus triplet propargylene (63.5percent) than earlier predictions. Extensive calculations onthe C 3 H 3 and C 3 H 2 D system combined with experimental isotope ratios for the CD + C 2 H2 reaction indicate that H-atom-assisted isomerization in the present experiments is responsible for the remaining discrepancy between the new RRKM calculations and the experimental results. Cyclic isomers are also found to represent 30(±6)percent of the detected products in the case of CH + methylacetylene, together with 33(±6)percent 1,2,3- butatriene and 37(±6)percent vinylacetylene. The CH + allene reaction gives 23(±5)percent 1,2,3-butatriene and 77(±5)percent vinylacetylene, whereas cyclic isomers are produced below the detection limit in this reaction. The reaction exit channels deduced by comparing the product distributions for the aforementioned reactions are discussed in detail.
Goulay, Fabien,Trevitt, Adam J.,Meloni, Giovanni,Selby, Talitha M.,Osborn, David L.,et al.
experimental part
p. 993 - 1005
(2009/06/28)

First total synthesis of cassiarin A, a naturally occurring potent antiplasmodial alkaloid
The first total synthesis of cassiarin A, an antiplasmodial alkaloid isolated from Cassia siamea, was achieved via sequential alkynylation of arenes with Sonogashira coupling and 6-endo-dig-cyclization of phenolic oxygens to the resulting alkynes.
Rudyanto, Marcellino,Tomizawa, Yuichiro,Morita, Hiroshi,Honda, Toshio
supporting information; experimental part
p. 1921 - 1922
(2009/04/10)

Detailed chemical kinetic modeling of pyrolysis of ethylene, acetylene, and propylene at 1073-1373 K with a plug-flow reactor model
This study examines the predictive capability of our recently proposed reaction mechanism (Norinaga and Deutschmann, Ind Eng Chem Res 2007, 46, 3547) for hydrocarbon pyrolysis at varying temperature. The conventional flow reactor experiments were conducted at 8 kPa, over the temperature range 1073-1373 K, using ethylene, acetylene, and propylene as reactants to validate the mechanism. More than 40 compounds were identified and quantitatively analyzed by on- and off-line gas chromatography. The chemical reaction schemes consisting of 227 species and 827 reactions were coupled with a plug-flow reactor model that incorporated the experimentally measured axial temperature profile of the reactor. Comparisons between the computations and the experiments are presented for more than 30 products including hydrogen and hydrocarbons ranging from methane to coronene as a function of temperature. The model can predict the compositions of major products (mole fractions larger than 10-2) in the pyrolysis of three hydrocarbons with satisfactory accuracies over the whole temperature range considered. Mole fraction profiles of minor compounds including polycyclic aromatic hydrocarbons (PAHs) up to three ring systems, such as phenanthrene, anthracene, and phenylnaphthalene, are also fairly modeled. At temperatures lower than 1273 K, larger PAHs were underpredicted and the deviation became larger with decreasing temperature and increasing molecular mass of PAHs, while better agreements were found at temperatures higher than 1323 K.
Norinaga, Koyo,Janardhanan, Vinod M.,Deutschmann, Olaf
p. 199 - 208
(2008/09/18)

Novel process and catalyst for carbon dioxide conversion to energy generating products
A catalytic process and a nano material for the conversion of moist carbon dioxide into methanol, propyne and oxygen have been developed. In the process invented, hydrogen is produced from water in a catalytic reaction, when the moist carbon dioxide enters into the catalytic reactor, resulting in C—O and H—OH bond breakage at a relatively low temperature and at atmospheric pressure in a single step using a combination of catalytic materials comprising at least three metals dispersed on a catalyst support, preferably anatase form of titanium dioxide, to induce a multifunctional surface chemical reaction for the production of oxygenated products such as hydrocarbons of different chain lengths.
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(2008/12/09)

METHYL METHACRYLATE PRODUCTION PROCESS
A method of producing methyl methacrylate comprising the following steps: Thermal decomposition step: a hydrocarbon having 3 or more carbon atoms is thermally decomposed to obtain a decomposed gas having a total content of propyne and propadiene of 2 wt% or more, Separation step: mixed liquid rich in propyne and propadiene is separated from the decomposed gas obtained in the thermal decomposition step, Propyne purification step: the mixed liquid rich in propyne and propadiene obtained in the separation step is subjected to extractive distillation, for separation into purified propyne, and crude propadiene containing propadiene as the main component, Isomerization step: the crude propadiene obtained in the propyne purification step is isomerized in the presence of an isomerization catalyst, to obtain crude propyne containing propyne as the main component, and Carbonylation step: the purified propyne obtained in the propyne purification step is reacted with carbon monoxide and methanol in the presence of a group VIII metal catalyst system, to produce methyl methacrylate.
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(2009/01/24)

Production of Propylene and Ethylene from Butane and Ethane
The present invention relates to a process for producing propylene and ethylene from a light hydrocarbon stream comprising essentially ethane and butane. The process involves a non-catalytic cracking of ethane and normal-butane followed by a metathesis of ethylene and 2-butene to increase the propylene yield. Optionally the by-produced iso-butane is dehydrogenated and subsequently the produced iso-butene is converted to other valuable products like di-isobutylene, alkylate for gasoline blending, tertiary-butyl-ethers, polyisobutylene, methyl-metacrylate or isoprene.
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(2008/06/13)

Unique σ-bond metathesis of silylalkynes promoted by an ansa-dimethylsilyl and oxo-bridged uranium metallocene
The tetrachloride salt of uranium reacts with 1 equiv of the lithium ligand Li2[(C5Me4)2SiMe2] in DME to form the complex [η5-(C5Me4)2SiMe2]UCl2·2LiCl·2DME (1), which undergoes a rapid hydrolysis in toluene to yield the dimeric bridged monochloride, monooxide complex [{[η5-(C5Me4)2SiMe2]UCl}2(μ-O)(μ-Cl)?Li?1/2DME]2 (2). Metathesis of 2 with BuLi in DME gives the mono-bridged dibutyl complex {[η5-(C5Me4)2SiMe2]UBu}2(μ-O) (3). Complex 2 was characterized by solid-state X-ray analysis. Complex 3 was found to be an active catalyst for the disproportionation metathesis of TMSC≡CH (TMS = SiMe3) and the cross-metathesis of TMSC≡CH or TMSC≡CTMS with various terminal alkynes. The metathesis of TMSC≡CH gives TMSC≡CTMS and HC≡CH, whereas the cross-metathesis of TMSC≡CH or TMSC≡CTMS with terminal alkynes (RC≡CH) yields TMSC≡CTMS, TMSC≡CR, and HC≡CH. In addition, TMSC≡CCH3 also was found to react with tBuC≡CH, yielding TMSC≡CBut and CH3C≡CH. A plausible mechanism for the catalytic process is presented. Copyright
Wang, Jiaxi,Gurevich, Ylia,Botoshansky, Mark,Eisen, Moris S.
p. 9350 - 9351
(2007/10/03)

Reaction of C-silylated α-diazophosphines as nucleophiles toward carbonyl compounds: A mechanistic study and application to the synthesis of alkynes and α-hydroxyphosphonamides
Diversely substituted α-hydroxyphosphonamides and alkynes have been efficiently synthesized through the reaction of C-silylated α- diazophosphines with different types of aldehydes (2 equiv) in a neutral medium under very mild conditions. The reaction with some chiral aldehydes is highly diastereoselective leading to phosphonamides as single diastereomers. The novel reaction is influenced by electronic and steric effects being precluded for aromatic aldehydes containing electron-releasing substituents on the phenyl ring and for bulky aliphatic aldehydes. The mechanistic studies of these processes, which are highly exothermic, provide evidence for a nucleophilic attack of the diazophosphine to the aldehyde leading to a betaine that rapidly rearranges to a diazomethylenephosphorane, which has been detected or captured in some instances. The diazomethylenephosphorane reacts with a second molecule of aldehyde according to a Wittig-type condensation, and the rate-determining step of the whole process is believed to be the decomposition of the resultant oxaphosphetane to afford the hydroxyphosphonamide and a diazocumulene. Finally, this intermediate loses molecular nitrogen giving a transient carbene that rapidly evolves toward the alkyne.
Illa, Ona,Bagan, Xavier,Cazorla, Anna M.,Lyon, Celine,Baceiredo, Antoine,Branchadell, Vicenc,Ortuno, Rosa M.
p. 5320 - 5327
(2007/10/03)

Synthesis of epothilones, intermediates thereto and analogues thereof
The present invention provides convergent processes for preparing epothilones, desoxyepothilones, and analogues thereof. The present invention further provides novel compositions and methods for the treatment of cancer and additionally provides methods for the treatment of cancer which has developed a multi-drug phenotype.
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(2008/06/13)

On-line analysis of gas-phase composition in the combustion chamber and particle emission characteristics during combustion of wood and waste in a small batch reactor
The emission of participate matter and gaseous compounds during combustion of wood and refuse-derived fuel in a small batch reactor is investigated by laser mass-spectrometric on-line measurement techniques for gas-phase analysis and simultaneous registration of physical aerosol properties (number size distribution). The gas-phase composition is addressed by a laser-based mass spectrometric method, namely, vacuum-UV single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Particle-size distributions are measured with a scanning mobility particle sizer. Furthermore, a photoelectric aerosol sensor is applied for detection of particle-bound polycyclic aromatic hydrocarbons. The different phases of wood combustion are distinguishable by both the chemical profiles of gas-phase components (e.g., polycyclic aromatic hydrocarbons, PAH) and the particle-size distribution. Furthermore, short disturbances of the combustion process due to air supply shortages are investigated regarding their effect on particle-size distribution and gas-phase composition, respectively. It is shown that the combustion conditions strongly influence the particle-size distribution as well as on the emission of particle-bound polycyclic aromatic hydrocarbons.
Ferge,Maguhn,Hafner,Muehlberger,Davidovic,Warnecke,Zimmermann
p. 1393 - 1402
(2007/10/03)

Recycling oxygenate-rich streams in oxygenate-to-olefin processes
A process and apparatus are provided for converting oxygenate to olefins which comprises: contacting a feedstock comprising oxygenate with a catalyst comprising a molecular sieve under conditions effective to produce a vaporous product comprising the olefins, water and unreacted oxygenate; condensing the vaporous product to provide a liquid stream rich in the water and unreacted oxygenate, and an olefins-rich vapor stream; introducing at least part of the liquid stream to a feed tray in a fractionation tower which provides an oxygenate-rich overhead product and a water-rich liquid bottoms product; providing a liquid, oxygenate-rich stream comprising at least about 20 wt % oxygenate above the feed tray; and passing the olefins-rich vapor stream through a recovery train to recover at least some of the olefins.
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Page/Page column 11-13

(2008/06/13)

Molecular library obtained by allene insertion into the Pd-C bond of cyclopalladated complexes: Biological and pharmacological evaluation
A minilibrary of cationic N-heterocycles has been prepared and evaluated. The potential for the preparation was a result of the high versatility of palladium-mediated chemistry. The synthesis of the novel molecules was based on intramolecular quaternization of tertiary amine attached allylpalladium complexes. The steric and electronic factors of the reaction are discussed. The structures of the synthesized molecules made them candidates for precise biological and pharmacological evaluations. Of the various N-heterocyclic compounds, 2,2-dimethyl-3-methylenenaphtho[de/]quinolizinium showed antibacterial activity at micromolar concentrations. This compound also proved to be a nanomolar competitive antagonist for the channel site of the nicotinic acetylcholine receptor. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Sirlin, Claude,Chengebroyen, Jaganaiden,Konrath, Renato,Ebeling, Guenther,Raad, Imad,Dupont, Jairton,Paschaki, Marie,Kotzyba-Hibert, Florence,Harf-Monteil, Colette,Pfeffer, Michel
p. 1724 - 1731
(2007/10/03)

Acetaldehyde dehydration to produce ethyne
A process to produce ethyne comprising passing acetaldehyde in the gas phase through a reaction zone containing a dehydrating metal oxide catalyst such as aluminum oxide or magnesium oxide at a temperature of approximately 375 C. to produce ethyne and water and a cooling zone following the reaction zone. This method having the advantage of ease of separation of ethyne from the co-product water and unreacted acetaldehyde by simple condensation whereby the acetaldehyde and water liquify while The ethyne remains gaseous.
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Page 1

(2008/06/13)

Semivolatile and volatile compounds in combustion of polyethylene
The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
p. 615 - 627
(2007/10/03)

Synthesis and pyrolytic and kinetic behaviour of β,δ′-dioxo-stabilised phosphorus ylides: Convenient preparation of γ,δ-alkynyl ketones and 2,3-functionalised butadienes
Both ketone- and ester-stabilised phosphorus ylides undergo Michael addition to vinyl ketones to give the β,δ′-dioxo ylides 3 and 5, respectively, although in the latter case careful temperature control is required to avoid an undesired side-reaction. Under conditions of flash vacuum pyrolysis at 650 °C the ylides 3 generally undergo Ph3PO extrusion to afford the γ,δ-alkynyl ketones 14, although these are found to partly undergo a secondary fragmentation. In contrast, the ylides 5 react under the same conditions to give the synthetically useful 1,3-dienes 20 by way of cyclobutenes. Rate constants for the reaction of selected ylides 3 and 5 are reported. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
Aitken, R. Alan,Al-Awadi, Nouria A.,Balkovich, Mark E.,Bestmann, Hans Juergen,Clem, Oliver,Gibson, Scott,Gross, Andreas,Kumar, Ajith,Roeder, Thomas
p. 840 - 847
(2007/10/03)

Thermal decomposition of 2-bromopropene, and 2-chloropropene
2-Chloropropene and 2-bromopropene have been decomposed in single pulse shock tube experiments. The only products under all conditions are propyne and allene. The high pressure rate expressions are k(2-BrC3H5 propyne/allene + HBr) =
Roy, Karin,Awan, Iftikhar A.,Manion, Jeffrey A.,Tsang, Wing
p. 1806 - 1810
(2007/10/03)

Synthesis of epothilones, intermediates thereto and analogues thereof
The present invention provides convergent processes for preparing epothilones, desoxyepothilones, and analogues thereof. The present invention further provides novel compositions and methods for the treatment of cancer and additionally provides methods for the treatment of cancer which has developed a multi-drug phenotype.
-
(2008/06/13)

Preparation of preparing substituted indanones
a process for the preparation of indanones of the formula II from, indanones of the formula I or of indanones of the formula IIa from indanones of the formula Ia comprises reacting an indanone of the formula I or Ia with a coupling component.
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(2008/06/13)

In situ generation of 1-propyne: A useful introduction of 1-propyne on unsaturated halogenated compounds through the sonogashira reaction
Reaction of (E/Z)-1-bromopropene with exactly 1.42 equivalents of nBuLi followed by addition of water produces in situ a THF solution of propyne. Addition of a vinylic or aromatic halogenated substrates, Pd(PPh3)2Cl2, CuI and an amine to this solution give high yield of the corresponding coupling product beating a propyne moiety. This practical procedure avoids the use of expensive and inflammable propyne gas which need a special apparatus for bubbling it into the reaction flask.
Abraham, Estelle,Suffert, Jean
p. 328 - 330
(2007/10/03)

Laser powered homogeneous pyrolysis of ethyne, propyne, and propadiene initiated by methyl radicals: Formation and degradation of hydrocarbons at 800-950 K
Applying laser heating by fast vibrational-translational energy transfer in a quasi-wall-free reactor the pyrolysis of ethyne (C2H2), propyne (p-C3H4), and propadiene (a-C3H4) was studied experimentally at 0.13 bar in the medium temperature range of 800-950 K with respect to the degradation and formation of hydrocarbons. The radical/hydrocarbon chemistry was chemically induced via CH3 radicals produced by the fast thermal dissociation of di-tert-butyl-peroxide DTBP ((tert-C4H9O)2 → 2 CH3 + 2 CH3COCH3). Complete analysis of the product yields was achieved by means of GC-MS with special attention to isomeric product and benzene formation. The product distribution, the temperature dependence and the underlying reaction schemes were analyzed by kinetic models developed for high temperature alkane oxidation/pyrolysis and aromatic formation in premixed ethene and ethyne flames. The primary attack of the unsaturated hydrocarbons by CH3 radicals in the studied temperature range occurs via the addition to the double/triple bond and via hydrogen atom abstraction, leading to different classes of radicals. For the reaction system C2H2 + CH3 high yields of C6H6 with a marked negative temperature dependence were observed. A semi-quantitative description of the C6H6 yield was obtained by a reaction sequence of successive addition of C2H2 to the radicals C2H3 (from C2H2 + H) and C4H5, being consistent with recent discussed reaction networks. For the reaction systems p-C3H4 + CH3 and a-C3H4 + CH3 only qualitative agreement between measured and modelled product yields was found, pointing to a lack of reliable data of the reactions of p-C3H4/a-C3H4/C3H 3/H. Modified mechanisms are presented for the radical rich reaction systems C2H2 + CH3, p-C3H4 + CH3, and a-C3H4 + CH3 experimentally studied.
Goos, Elke,Hippler, Horst,Hoyermann, Karlheinz,Juerges, Bettina
p. 2011 - 2018
(2007/10/03)

Electrosynthesis of Allene (propadiene) and of propyne (methylacetylene) through the anodic decarboxylation reaction (part 2)
The anodic decarboxylation reaction is a general reaction that can be applied with success to several suitable precursors. This work presents the electrochemical synthesis of allene by anodic oxidation of potassium itaconate. It is also shown that the anodic oxidation of potassium citraconate produces propyne. In both cases, unsaturated hydrocarbons were formed together with CO and CO2. The electrooxidation of potassium crotonate leads to a simultaneous formation of propyne and allene (the latter in considerably smaller amounts than the former). Also in this case, formation of the unsaturated hydrocarbons is accompanied by the formation of CO and CO2.
Cataldo, Franco
p. 77 - 88
(2007/10/03)

Crossed beam investigations of the reaction dynamics of O(3P) with allyl radical, C3H5
The nascent rovibrational distributions of the OH product from the newly observed exothermic reaction of O(3P)+C3H5→ C3H4+OH were studied. The atom-radical reaction dynamics was first probed through t
Kwon, Han-Cheol,Park, Jong-Ho,Lee, Hohjai,Kim, Hee-Kyung,Choi, Young-Sang,Choi, Jong-Ho
p. 2675 - 2679
(2007/10/03)

Flash vacuum pyrolysis over solid catalysts. 1. Pyrazoles over zeolitest
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
p. 2943 - 2947
(2007/10/03)

Experimental and modelling study of 1-pentene combustion at fuel-rich conditions
A fuel-rich, non-sooting (C/O = 0.773) 1-pentene/oxygen/argon flame is studied experimentally at 50 mbar. The results are compared to computations. The calculations show satisfactory agreement with the data obtained from the measurements. The main channels for 1-pentene decomposition are presented and discussed in view of previous data for a propene flame at similar experimental conditions. Special emphasis is directed towards the formation of the first aromatic ring and the further growth of small aromatic hydrocarbons. By reaction flow analysis, it is found that the major reaction channel for benzene formation results from the recombination of propargyl radicals. Furthermore, the major reaction channels for naphthalene formation are presented. by Oldenbourg Wissenschaftsverlag, Muenchen.
Gonzalez Alatorre,Boehm,Atakan,Kohse-Hoeinghaus
p. 981 - 995
(2007/10/03)

Detailed combustion kinetics of cyclopentadiene studied in a shock-tube
Mixtures of cyclopentadiene and oxygen diluted in argon were used obtain ignition delay data in a single pulse shock-tube. The temperatures ranged from 1278-2110 K and the experimental pressures were between 2.43 and 12.45 atm. The fuel concentrations ranged from 0.5 to 2.5% and the oxygen concentrations were between 3.3 and 16.6%. A Semenov ignition delay expression was determined: τ = 10-12.5 exp(+34500/RT) |C5H6|0.06 |O2|-0.95 |Ar|0.29 sec The concentrations are in mol/cc and the activation energy is in cal/mol Gas-chromatographic analyses were run on samples quenched before the ignition. The kinetics of combustion of cyclopentadiene was modeled with a full scheme containing 439 elementary reactions and a reduced scheme containing 125 reactions. Both ignition delay times and product distribution served as modeling target. The mechanism of combustion of cyclopentadiene is discussed in connection to the combustion of aromat ic fuels.
Burcat, Alexander,Dvinyaninov, Michael,Olchanski, Erna
p. 491 - 508
(2007/10/03)

1,2-Pentadiene decomposition
1,2-Pentadiene was decomposed in single pulse shock tube experiments. There appear to be a large number of parallel decomposition and isomerization channels. It was shown that the resonance energy of the 1,3-butadiene-2-yl radical is smaller than that of allyl radical by an amount equal to the π bond conjugation energy of butadiene.
Herzler, Juergen,Manion, Jeffrey A.,Tsang, Wing
p. 755 - 767
(2007/10/03)

The gas-phase pyrolysis of 2,2-dinitropropane: Shock-tube kinetics
The thermal decomposition of 2,2-dinitropropane (DNP) was studied in a shock tube at 970-1200 K, under high dilution in argon at 4.5-5.5 atm. The decay of DNP and the production of NO2 were followed spectrophotometrically at 280 and 405 nm, respectively. The major products were CO, NO, CO2, acetone, CH3C≡H, CH2=C=CH2, CH3CN, CH3OH, CH4, H2O, and CH2O. The first step in the decomposition was C-NO2 bond fission. However, the temporal profiles of NO2 during the decomposition were different from those recorded during the decompositions of CH3NO2 or 2-nitropropane, thus pointing to distinctive features in the mechanism. A complation of 90 elementary steps was proposed. Sensitivity analysis of the mechanism showed that only 57 steps were essential to describe the overall pyrolysis. H,OH, NO2. HCO, and HNO played critical roles in the decomposition.
Zhang, Yi-Xue,Bauer
p. 1217 - 1225
(2007/10/03)