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Cas Database

74-86-2

74-86-2

Identification

  • Product Name:Ethyne

  • CAS Number: 74-86-2

  • EINECS:200-816-9

  • Molecular Weight:26.0379

  • Molecular Formula: C2H2

  • HS Code:2901292000

  • Mol File:74-86-2.mol

Synonyms:Acetylene(8CI);Vinylene (7CI);Ethine;Narcylen;

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Safety information and MSDS view more

  • Pictogram(s):HighlyF+

  • Hazard Codes: F+:Highly flammable;

  • Signal Word:Danger

  • Hazard Statement:H220 Extremely flammable gas

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled Fresh air, rest. Artificial respiration may be needed. Refer for medical attention. In case of skin contact Wash off with soap and plenty of water. Consult a physician. In case of eye contact First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician. Headache, dizziness and loss of consciousness may occur. Death from ``smothering'' may occur if oxygen content of the air is severely reduced by dilution with acetylene. (USCG, 1999) Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Aliphatic hydrocarbons and related compounds/

  • Fire-fighting measures: Suitable extinguishing media Stop flow of gas before extinguishing fire. Use water spray to keep fire-exposed containers cool. Approach fire from upwind to avoid hazardous vapors and toxic decomposition products. Fight fire from protected location or maximum possible distance. Use water spray, dry chemical, form, or carbon dioxide. /Acetylene, dissolved/ Behavior in Fire: May explode in fire (USCG, 1999) Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Remove all ignition sources. Evacuate danger area! Consult an expert! Personal protection: self-contained breathing apparatus. Ventilation. Evacuate danger area! Consult an expert! Ventilation. Remove all ignition sources. (Extra personal protection: self-contained breathing apparatus).

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. Fireproof. See Chemical Dangers. Cool.Keep container in a cool, well-ventilated area. Keep container tightly closed and sealed until ready for use. Avoid all possible sources of ignition (spark or flame). Segregate from oxidizing materials. Cylinders should be stored upright, with valve protection cap in place, and firmly secured to prevent falling or being knocked over. Cylinder temperatures should not exceed 52 degC (125 degF).

  • Exposure controls/personal protection:Occupational Exposure limit valuesRecommended Exposure Limit: Ceiling Value: 2500 ppm (2662 mg/cu m).Biological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 551 Articles be found

Jenkins, W. J.

, p. 747 - 749 (1921)

Mitchell,Le Roy

, p. 2075 (1953)

High-Temperature Stabilities of Hydrocarbons

Stein, S. E.,Fahr, A.

, p. 3714 - 3725 (1985)

A chemical thermodynamic analysis of hydrocarbon molecules from 1500 to 3000 K is presented for species C2nH2m, n=1-21, m=1-8.With group additivity as the primary estimation method, the nature and chemical thermodynamic properties of the most stable molecules ( stabilomers ) are found.Concentrations of these molecules are then examined in equilibrium with acetylene and molecular hydrogen after taking into account numbers of isomers.Thermodynamically favored pathways leading to large, condensed polyaromatic species are examined in detail.Two general types of paths are found.At higher H2/C2H2 ratios (>=1), most species on these paths are polycyclic aromatic molecules and, depending on partial pressures of C2H2 and H2, a free energy barrier appears in the range 1400-1800 K which increases sharply with increasing temperature.At lower H2/C2H2 ratios, many smaller species are cyclic, and as this ratio becomes smaller the barrier declines and becomes less sensitive to temperature.A brief dicussion of the connection between these results and the kinetics of carbon polymerization is then presented.

Ko Taki et al.

, p. 1556 (1973)

-

Currell,Zechmeister

, p. 205 (1958)

-

Ion-molecule reactions of ArN2+ with simple aliphatic hydrocarbons at thermal energy

Tsuji, Masaharu,Matsumura, Ken-ichi,Kouno, Hiroyuki,Aizawa, Masato,Nishimura, Yukio

, p. 8687 - 8696 (1994)

The product ion distributions and rate constants are determined for ion-molecule reactions of ArN2+ with C2Hn (n=2,4,6) and C3Hn (n=6,8) by using a thermal ion-beam apparatus.Although charge-transfer channels leading to parent ions and/or fragment ions are found, no displacement reaction leading to ArCmHn+ and N2CmHn+ is detected.A comparison of the product ion distributions with breakdown patterns of the parent ions suggests that fragment ions, formed through cleavage of C-H and/or C-C bonds, are produced via near-resonant ionic states in the 13.1-13.4 eV range.The branching ratios of parent ions for C2H4 (68percent) and C3H6 (20percent) are larger than those for C2H6 (5percent) and C3H8 (5percent).The large branching ratios of the parent ions for the unsaturated hydrocarbons are explained as due to a strong interaction of a vacant orbital of ArN2+ with the highest occupied ?C=C orbital of the unsaturated hydrocarbons which induces nonresonant charge transfer.The total rate constant for C2H2 is 6.8x10-10 cm3 s-1, while those for C2Hn (n = 4,6) and C3Hn (n = 6,8) are in the range (8.5-9.8)x10-10 cm3 s-1.The former and the latter values correspond to 69percent and 77percent-90percent of the calculated values from Langevin or average dipole orientation (ADO) theory.The smaller kobs/kcalc ratio for C2H2 is attributed to the lack of near-resonant ionic states with favorable Franck-Condon factors for ionization.

Reactions of vinyl radicals at high temperatures: Pyrolysis of vinyl bromide iodide and the reaction H + C2D2 → D + C2HD

Rao,Skinner, Gordon B.

, p. 6313 - 6319 (1988)

Five sets of experiments were carried out to determine the rate constant for dissociation of C2H3 at high temperatures. In all cases the measurements involved absorption of H or D Lyman-α radiation in argon-diluted gas mixtures reacting behind shock waves. For pyrolysis of vinyl bromide at 0.5-atm total pressure we found for C2H3 + Ar → C2H2 + H + Ar, k = 7.0 × 1013 exp(-28 kcal/RT) mol-1 cm3 s-1 at 1380-1750 K. For the same reaction initiated from vinyl iodide at 0.5-atm total pressure and 1060-1370 K, we found k = 3.5 × 1014 exp(-33 kcal/RT) mol-1 cm3 s-1. In three sets of experiments in which H atoms reacted with C2D2 to produce D atoms, we obtained values of k∞ for the reaction H + C2H2 → C2H3 of 8 × 1011, 1.2 × 1012, and 3.4 × 1012 mol-1 cm3 s-1 in the temperature range 1200-1900 K, with no clearly visible temperature dependence. All of the experimental values lie 3-10 times lower than those deduced from earlier work at high temperatures or based on ab initio calculations for the vinyl radical.

The Dewar Isomer of 1,2-Dihydro-1,2-azaborinines: Isolation, Fragmentation, and Energy Storage

Edel, Klara,Yang, Xinyu,Ishibashi, Jacob S. A.,Lamm, Ashley N.,Maichle-M?ssmer, C?cilia,Giustra, Zachary X.,Liu, Shih-Yuan,Bettinger, Holger F.

, (2018)

The photochemistry of 1,2-dihydro-1,2-azaborinine derivatives was studied under matrix isolation conditions and in solution. Photoisomerization occurs exclusively to the Dewar valence isomers upon irradiation with UV light (>280 nm) with high quantum yiel

Cazeneuve

, (1884)

Reactions of ethynyl radicals. Rate constants with CH4, C2H6, and C2D6

Laufer, Allan H.

, p. 3828 - 3831 (1981)

The rate constants for the abstraction of H atoms from CH4, C2H6, and D atoms from C2D6 by C2H (ethynyl) radicals have been determined by using a flash photolysis-kinetic spectroscopic technique. The values obtained, at 297 K, are (1.2 ± 0.2) × 10-12, (6.5 ± 0.4) × 10-12, and (3.1 ± 0.5) × 10-12 cm3 molecule-1 s-1, respectively. The rate constants are independent of added helium over the pressure range 20-700 torr. The kinetic parameters were determined by monitoring the acetylene product spectroscopically using C2H-CF3 as the source of ethynyl radicals.

Callear,Robb

, p. 21 (1954)

Lossing et al.

, p. 701,707 (1956)

Peters,Kuester

, (1931)

Ambartzumian et al.

, p. 301,302-303 (1975)

Thermal Decomposition of Energetic Materials. 25. Shifting of the Dominant Decomposition Site by Backbone Substitution of Alkylammonium Nitrate Salts

Oyumi, Y.,Brill, T. B.

, p. 3657 - 3661 (1987)

Exchanging X = -C(NO2)2F for X = -C(NO2)3 causes the dominating fast thermal decomposition site in NO3 salts to shift from largely that of the C-NO2 bond to largely that of the -H+...NO3- portion.This is consistent with an order of thermal stability of the energetic sites in these salts of -C(NO2)2F>-H+...NO3->-C(NO2)3.These conclusions were drawn from the nature of the IR-active gas products that are evolved in real time upon fast thermolysis (>100 K s-1) and from slow heating of the condensed phase.The O/H ratio of the parent primary ammonium salt appears to be a qualitative indicator of whether NH3(g) will formed under these conditions.Salts with O/H >/= 1 have not been observed to release NH3(g) while those with O/H 1 do.The salt with X=-C(NO2)2F possesses four polymorphs between 297 K and its two melting points.Only two polymorphs are present when X = -C(NO2)3.

Dehydrochlorination of 1,2-dichloroethane over Ba-modified Al2O3 catalysts

Bai, Shuxing,Dai, Qiguang,Chu, Xinxin,Wang, Xingyi

, p. 52564 - 52574 (2016)

Bimodal mesoporous alumina (Al2O3) was prepared using polyethyleneglycol (PEG 20,000) and cetyl trimethyl ammonium bromide as a template. The incorporation of Ba with various loadings was carried out by incipient wetness. Characterization was performed by XRD, N2 sorption isotherms, and pyridine FTIR. Ba can be highly dispersed on Al2O3 covering the strong acid sites of Al2O3. In the catalytic dehydrochlorination of 1,2-dichloroethane (1,2-DCE), the Ba/Al2O3 catalysts present a high activity, of which Al2O3 is most active with 95% conversion at 325 °C, related to the more Lewis acidic Al3+ sites in a tetrahedral environment. 1,2-DCE adsorbs dissociatively on Lewis acid-base pair sites, forming chlorinated ethoxy species, which are supposed to be intermediate species for vinyl chloride (VC) production. At a temperature higher than 400 °C, the dehydrochlorination of VC occurs on the strong acid sites of Al2O3. Ba can promote greatly the selectivity for VC through a decrease in the strong acid sites. A high stable activity for dehydrochlorination and high selectivity for VC can be obtained over Ba/Al2O3 in the presence of oxygen.

Surface kinetics using line of sight techniques: The reaction of chloroform with Cu(111)

Jones, Robert G.,Clifford, Charles A.

, p. 5223 - 5228 (1999)

The adsorption of chloroform (CHCl3) on Cu(111) in the temperature range 100-480 K has been studied using line of sight sticking probability (LOSSP) measurements, line of sight temperature programmed desorption (LOSTPD), low energy electron diffraction (LEED), He I ultra-violet photoelectron spectroscopy (UPS) and work function measurements. Chloroform adsorbs molecularly at 100 K with a sticking probability of 0.98 ± 0.02, the monolayer reacting on heating to 170 K to form chemisorbed chlorine and adsorbed ethyne. The adsorbed ethyne desorbs at just above room temperature with first order kinetics, an activation energy of 77 ± 6 kJ mol-1 and a pre-exponential factor of 10(11±1) s-1. The sticking probability of chloroform on clean Cu(111) at 320 K is 0.23 ± 0.04, which corresponds to activated adsorption at zero coverage with an activation energy of 3.5 ± 0.7 kJ mol-1. The initial sticking probability is found to increase slightly for temperatures above room temperature, and also for temperatures below room temperature, while the sticking probability at finite coverage is greatly increased by the presence of the dissociation product, ethyne, on the surface. These observations are explained in terms of activated adsorption at zero coverage which becomes non-activated at finite coverage due to attractive intermolecular interactions between adsorbed chloroform molecules, and adsorbed chloroform and ethyne molecules.

Competition between photochemistry and energy transfer in ultraviolet-excited diazabenzenes. I. Photofragmentation studies of pyrazine at 248 nm and 266 nm

Sevy, Eric T.,Muyskens, Mark A.,Rubin, Seth M.,Flynn, George W.,Muckerman, James T.

, p. 5829 - 5843 (2000)

The quantum yield for the formation of HCN from the photodissociation of pyrazine excited at 248 nm and 266 nm is determined by IR diode probing of the HCN photoproduct. HCN photoproducts from excited pyrazine are produced via three different dissociation channels, one that is extremely prompt and two others that are late. The total quantum yield from all reaction channels obtained at low quencher gas pressures, φ = 1.3 ± 0.2 for 248 nm and 0.5 ± 0.3 for 266 nm, is in agreement with preliminary studies of this process as well as recent molecular beam studies. To investigate if HCN production is the result of pyrazine multiphoton absorption, this photodissociation process has been further studied by observing the HCN quantum yield as a function of total quencher gas pressure (10 mTorr pyrazine, balance SF6) and as a function of 248 nm laser fluence from 2.8 to 82 mJ/cm2. At the highest SF6 pressures, the HCN quantum yield shows strong positive correlation with laser fluence, indicating that the prompt channel is the result of multiphoton absorption; however, at low pressure, the HCN quantum yield is affected little by changing laser fluence, indicating that the majority of the HCN photoproducts at low pressure are produced from pyrazine which has absorbed only one UV photon. At the lowest pressures sampled, HCN produced from the one-photon late process accounts for more than 95% of all HCN formed (at low laser fluence). At high pressures the single photon late pyrazine dissociation is quenched, and HCN produced at high quencher gas pressures comes only from the multiphoton absorption channel, which can be clearly observed to depend on laser fluence. The HCN quantum yield as a function of laser intensity at high pressure has been fit to a quadratic function that can be used to determine the amount of prompt unquenched HCN produced from multiphoton photodissociation. Additionally, the information theoretic prior functions for energy disposal in the 248 nm photodissociation of pyrazine to form HCN have also been developed. Prior functions for one, two, and three-photon absorption indicate that only HCN with near room temperature translational energy comes from the one-photon process and that all HCN molecules with large amounts of translational energy are produced by multiphoton processes. Finally, analysis of the quenching data within the context of a strong collision model allows an estimate of the rate constant for HCN production from pyrazine for the major late channel, kdls = 1.69 × 105 s-1, for 248 nm excitation, and kdls = 1.33 × 104 s-1 for 266 nm excitation. After 266 nm excitation, pyrazine produced by the major one-photon channel lives for almost an order of magnitude longer than after 248 nm excitation.

Beletskaya et al.

, p. 485 (1969)

Kim et al.

, p. 2953 (1975)

Burns,Reed

, p. 101,107 (1963)

Corbin et al.

, p. 7862,7863 (1976)

Stief,Decarlo

, p. 839 (1969)

Darwent

, (1953)

Nicholas et al.

, p. 1610,1611 (1966)

Photochemical reactions of cis- and trans-1,2-dichloroethene adsorbed on Pd(111) and Pt(111)

Grassian, Vicki H.,Pimentel, George C.

, p. 4484 - 4491 (1988)

The photochemical behaviors of cis- and trans-1,2-dichloroethene (DCE) adsorbed on Pd ( 111 ) and Pt ( 111 ) surfaces have been studied using electron energy loss spectroscopy ( EELS ) .For multilayer coverage on either metal surface, irradiation of physisorbed DCE at 110 K with broad band irradiation (λ > 200 nm) results in photoisomerization, cistrans.For monolayer coverage on Pt ( 111 ) at 110 K, photolysis of chemisorbed DCE causes loss of the two chlorine atoms to form a single hydrocarbon product, chemisorbed acetylene.Apparently, for λ > 237 nm, the chlorine atoms remain bound to the platinum surface whereas for shorter wavelengths, λ > 200 nm, the chlorine atoms leave the surface.These results are interpretable in terms of singlet excitation of the chemisorbed alkane followed by chlorine elimination on an excited singlet reaction surface.This study indicates that photochemistry of molecules chemisorbed on a metal surface is possible despite the proximity of the conducting surface.It shows that energy relaxation processes connected with this proximity are not prohibitively fast.

Formation of Acetylene in the Reaction of Methane with Iron Carbide Cluster Anions FeC3? under High-Temperature Conditions

Li, Hai-Fang,Jiang, Li-Xue,Zhao, Yan-Xia,Liu, Qing-Yu,Zhang, Ting,He, Sheng-Gui

, p. 2662 - 2666 (2018)

The underlying mechanism for non-oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C?C bond. For the first time, the elementary reaction of methane with atomic clusters (FeC3?) under high-temperature conditions to produce C?C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well-rationalized by quantum chemistry calculations. This study narrows the gap between gas-phase and condensed-phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non-oxidative methane aromatization.

Translational energy distributions and angular difference Doppler profiles of the excited hydrogen atom produced in e-C2H4 collisions: Dissociation dynamics of ethylene

Yonekura, Nobuaki,Nakashima, Keiji,Ogawa, Teiichiro

, p. 6276 - 6282 (1992)

Formation of an excited hydrogen atom (H*) through electron-impact dissociation of ethylene has been investigate by measuring Doppler profiles of the Balmer-β line and their angular dependence at an optical resolution of 0.007 nm.The Doppler profiles show a clear anisotropy.The translational energy distribution (TED) and the angular difference Doppler profile were obtained.There are four major dissociation processes for the formation of H* (n = 4).Component 1 has a peak of TED at 1 eV, is produced in a perpendicular distribution, and should be produced by predissociation through the Rydberg states converging to the (1b1u)-1 state.Component 2 has a peak of TED at 1.8 eV, is produced in a parallel distribution, and should be produced through the Rydberg states converging to the (2ag)-1 state.Component 3 has a peak of TED at 2-6 eV and is produced in a parallel distribution.Component 4 has a peak of TED at 5-10 eV.Molecular orientation at the time of excitation was estimated; the molecular plane is perpendicular to the electron beam for component 1, and the C=C bond is perpendicular and the molecular plane is parallel to the electron beam for components 2 and 3.The asymmetry parameters of components 2 and 3 were 0.2: these values were much smaller than anticipated due largely to molecular rotation and deformation at the time of dissociation.

Photodissociation of 1,2-C2H2Br2 at 248 nm: Competition between three-body formation Br+Br+C2H2 and molecular Br2 elimination

Lee,Chou,Lee,Wang,Lin

, p. 3195 - 3200 (2001)

The photodissociation of 1,2-C2H2Br2 was studied using product translational spectroscopy. A detector consisting of an electron impact ionizer, quadrupole mass filter and Daly type ion counter was used to measure the dissociation production after travelling a flight path of 365 mm from the reaction zone. Experimental analysis suggested that the dissociation of the molecule into triple products was due to an asynchronous concerted reaction. Behavior of the molecule in the presence of additional bromine atom and the molecular elimination of Br2 were also studied. The product anisotropy indicated that both Br fragments were produced in a fraction of rotational period.

Unimolecular Dissociation of Vinylacetylene: A Molecular Reaction

Kiefer, J. H.,Mitchell, K. I.,Kern, R. D.,Yong, J. N.

, p. 677 - 685 (1988)

The thermal decomposition of vinylacetylene (C4H4) has been studied in the shock tube with two time-resolved diagnostics, laser-schlieren (2percent and 4percent C4H4-Kr, 1650-2500 K, 110-427 Torr) and time-of-flight mass spectrometry (2percent C4H4-Ne, 1500-2000 K, 150-300 Torr).The time-of-flight mass spectra show dominant products C2H2 and C4H2 with a very consistent 5:1 ratio of C2H2 to C4H2, in essential agreement with earlier shock tube results.The laser-schlieren semilog density gradient profiles are all concave-upward, showing no trace of chain acceleration.Analysis of these profiles also sets the effective heat of reaction between 30 and 50 kcal/mol.Rate constants calculated from the zero-time gradients assuming ΔH0298 = 40 kcal/mol are fit with a routine RRKM model which indicates a barrier E0=79.5 +/- 3 kcal/mol.These observations and the time-of-flight product profiles are consistent with the molecular reactions C4H4 --> 2C2H2 (ΔH0298 = 39 kcal/mol)and C4H4 --> C4H2+H2(ΔH0298 = 42 kcal/mol).Detailed balance rate constants for 2C2H2 --> C4H4 are in good agreement with the extensive previous data on the second-order acetylene reaction, confirming that vinylacetylene is a direct and dominant product of C2H2 dimerization for moderate temperatures.Above 1500 K, the C4H4 dissociation shows significant falloff even for high pressures, and the now dominant C4H2 in C2H2 pyrolysis may then be formed in part through 2C2H2 --> C4H2 + H2.It is proposed that vinylacetylene dissociates as a substituted ethylene, either by 1,1-elimination of molecular hydrogen, leaving vinylidene acetylene which rapidly isomerizes to C4H2, or by 2,2-elimination of C2H2, followed by rapid isomerization of the vinylidene to a second C2H2.This mechanism is consistent with the observed barrier, provides a rationale for the constancy of the C2H2/C4H2 ratio, and offers a resonable explanation for the magnitude (A factor) of the observed rate constants.

The synthesis of ternary acetylides with tellurium: Li2TeC2 and Na2TeC2

Németh, Károly,Unni, Aditya K.,Kalnmals, Christopher,Segre, Carlo U.,Kaduk, James,Bloom, Ira D.,Maroni, Victor A.

, p. 55986 - 55993 (2015)

The synthesis of ternary acetylides Li2TeC2 and Na2TeC2 is presented as the first example of ternary acetylides with metalloid elements instead of transition metals. The synthesis was carried out by the direct reaction of the corresponding bialkali acetylides with tellurium powder in liquid ammonia. Alternatively, the synthesis of Na2TeC2 was also carried out by the direct reaction of tellurium powder and two equivalents of NaC2H in liquid ammonia leading to Na2TeC2 and acetylene gas through an equilibrium containing the assumed NaTeC2H molecules besides the reactants and the products. The resulting disordered crystalline materials were characterized by X-ray diffraction and Raman spectroscopy. Implications of these new syntheses on the synthesis of other ternary acetylides with metalloid elements and transition metals are also discussed.

Shida et al.

, p. 245 (1958)

Miller,Noyes

, p. 3403 (1952)

Sprangler et al.

, p. 842 (1966)

Evidence for a difference in the dissociation mechanisms of acetylene (HCCH) and vinylidene (H2C=C:) from charge inversion mass spectrometry

Hayakawa, Shigeo,Tomozawa, Kouji,Takeuchi, Takae,Arakawa, Kazuo,Morishita, Norio

, p. 2386 - 2390 (2003)

Vinylidene and acetylene are the simplest hydrocarbon isomers, and vinylidene is the simplest unsaturated carbene. The charge inversion mass spectra of C2H2+ cations derived from acetylene using Na, K, Rb and Cs targets were found to be clearly different from those derived from vinylidenechloride (1,1-dichloroethylene). The process of formation of the negative ions in charge inversion mass spectrometry is via near-resonant neutralization followed by spontaneous dissociation, and then endothermic negative ion formation. The intensity of the C2- peak relative to the C2H- peak in these spectra increased with decreasing ionization potential of the targets for both of the isomeric C2H2+ cations. The formation of the C2- anion is proposed to result from the dissociation of excited C2H2 neutrals into C2 and H2. The dependence on target species of the intensities of the C2- peak relative to the C2H- peak for HCCH and H2C=C: cannot be rationalized by the internal energy of the excited C2H2 neutrals. The differences indicate that the isomeric C2H2 neutrals dissociate into C2H and H prior to 1,2-hydrogen atom migration.

Two-photon photodissociation of gaseous azulene at 325 nm

Hassoon, S.,Snavely, D. L.,Oref, I.

, p. 9081 - 9085 (1992)

The two-photon photodissociation of gaseous azulene at 325 nm is reported.Acetylene is the major photodissociation product.The quantum yields for acetylene produced by irradiation of neat azulene at its normal vapor pressure and as a function of argon bath gas pressure are reported.The quantum yield of acetylene produced from irradiated azulene at its normal vapor pressure (ca. 10 m Torr) is ca. (5.85+/-1.46) * 10-6.Using a mechanism by which internal conversion precedes the absorption of the second photon, the two-photon absorption cross section is calculated.

Influence of low-voltage discharge energy on the morphology of carbon nanostructures in induced benzene transformation

Bodrikov, Ivan Vasilievich,Ivanova, Anna Gennadevna,Serov, Anton Igorevich,Titov, Dmitry Yurievich,Titov, Evgeny Yurievich,Vasiliev, Alexander Leonidovich

, p. 39428 - 39437 (2021/12/24)

The directions of the transformation of benzene induced by low-voltage discharges at various energies of pulsed discharges were revealed. This paper shows the dependencies of the morphology and other characteristics of nanostructures obtained in the induced transformation of benzene on the energy of pulsed discharges. Nanostructures with different morphologies are formed when the energy of the low-voltage discharges changes during the induced transformation of benzene in the liquid phase. Two types of carbon nanostructures were formed in the induced destruction of benzene with a 90 μF capacitor. The first type of structure includes graphite fibers, two- and three-layer graphene sheets, as well as two- and three-layer hollow spheres and microstructures in the form of CNHs. The microstructures of the second type were onion-like spheroids. An increase in the capacitance up to 20?090 μF led to the formation of two types of nanostructures: onion-like spheroids and carbon fibers. A further increase in the capacitance to 40?090 μF caused the formation of onion-like spheroids.

Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes

Mohamed, Amira A.,Elshafie, Hazem S.,Sadeek, Sadeek A.,Camele, Ippolito

, (2021/07/26)

String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4′E)-4,4′-(ethane-1,2-diyldiazanylylidene)bis{7-[(4Z

Reactors for Preparing Valuable Hydrocarbons and Hydrogen From Methane Through Non-Oxidative Pyrolysis

-

Paragraph 0084-0091; 0099, (2021/10/11)

According to this disclosure, there is provided a pyrolysis reaction system and a direct non-oxidative methane coupling process using the same by which it is possible to reach the selectivity for good C≤10 hydrocarbons and at the same time to inhibit coke from being generated while a good methane conversion is maintained during direct conversion of methane into C2+ hydrocarbons through non-oxidative pyrolysis.

Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled

?ot, Petr,Hemberger, Patrick,Pan, Zeyou,Paunovi?, Vladimir,Puente-Urbina, Allen,van Bokhoven, Jeroen Anton

supporting information, p. 24002 - 24007 (2021/10/01)

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.

Practical Gas Cylinder-Free Preparations of Important Transition Metal-Based Precatalysts Requiring Gaseous Reagents

Ahrens, Alexander,Donslund, Bjarke S.,Gausas, Laurynas,Kristensen, Steffan K.,Skrydstrup, Troels,Sun, Hongwei

supporting information, p. 2300 - 2307 (2021/09/28)

A simple and safe setup for the synthesis of a selection of important transition metal-based precatalysts is reported, all requiring low-molecular weight gaseous reagents for their preparation. Hydrogen, carbon monoxide, ethylene, and acetylene are each liberated in a controlled manner from a corresponding easy-to-handle precursor in a closed two-chamber reactor. Gas cylinders and elaborate setups/techniques connected to handling toxic and/or flammable gases as reported in the literature can thus be avoided. The corresponding precatalysts are of high relevance in the active research fields of C-H bond activation, dehydrogenation, hydrogenation, and coupling reactions. The selection of complexes shown is meant to serve as examples for the usefulness and broadness of the presented methods, allowing precatalysts requiring gaseous reagents to become available for the research community.

Process route upstream and downstream products

Process route

Vinyl bromide
593-60-2,25951-54-6

Vinyl bromide

water
7732-18-5

water

potassium acetate
127-08-2

potassium acetate

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
Vinyl bromide
593-60-2,25951-54-6

Vinyl bromide

sodium pentanolate
1941-84-0

sodium pentanolate

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
at 100 ℃;
Vinyl bromide
593-60-2,25951-54-6

Vinyl bromide

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
at 100 ℃;
Vinyl bromide
593-60-2,25951-54-6

Vinyl bromide

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
1-bromo-2-iodoethane
590-16-9

1-bromo-2-iodoethane

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

hydrogen iodide
10034-85-2

hydrogen iodide

Conditions
Conditions Yield
beim Erwaermen;
Conditions
Conditions Yield
at 1000 - 1100 ℃; under 820.855 Torr;
12.6 %Chromat.
3.39 %Chromat.
26 %Chromat.
0.35 %Chromat.
0.49 %Chromat.
15.1 %Chromat.
4.02 %Chromat.
3.65 %Chromat.
2.95 %Chromat.
4.85 %Chromat.
2.33 %Chromat.
0.77 %Chromat.
aluminum oxide; iron(III) oxide; at 1000 - 1100 ℃; under 820.855 Torr;
16.53 %Chromat.
4.01 %Chromat.
31.78 %Chromat.
0.49 %Chromat.
0.5 %Chromat.
16.02 %Chromat.
4.71 %Chromat.
0.76 %Chromat.
0.54 %Chromat.
4.2 %Chromat.
3.05 %Chromat.
1.06 %Chromat.
hexane
110-54-3

hexane

2-ethyltetrahydrofuran
1003-30-1,123931-62-4

2-ethyltetrahydrofuran

2-ethyl-4-methyloxetane
5410-21-9

2-ethyl-4-methyloxetane

2,5-dimethyltetrahydrofuran
1003-38-9

2,5-dimethyltetrahydrofuran

2-methyloxane
10141-72-7

2-methyloxane

1,2-Epoxyhexane
1436-34-6

1,2-Epoxyhexane

2,3-epoxyhexane
1192-32-1

2,3-epoxyhexane

2-propyl-oxetane
4468-64-8

2-propyl-oxetane

methanol
67-56-1

methanol

Ketene
463-51-4

Ketene

ethane
74-84-0

ethane

ethene
74-85-1

ethene

1,2-propanediene
463-49-0

1,2-propanediene

acetaldehyde
75-07-0,9002-91-9

acetaldehyde

acetic acid
64-19-7,77671-22-8

acetic acid

propionic acid
802294-64-0,79-09-4

propionic acid

methyloxirane
75-56-9,16033-71-9

methyloxirane

prop-1-yne
74-99-7

prop-1-yne

Conditions
Conditions Yield
With oxygen; at 376.84 ℃; for 0.000555556h; under 795.08 Torr; Temperature; Inert atmosphere;
1,1-Dichloro-2,5-dihydro-1H-silole
872-46-8

1,1-Dichloro-2,5-dihydro-1H-silole

dichlorosilylene
13569-32-9

dichlorosilylene

ethene
74-85-1

ethene

trichlorosilane
10025-78-2

trichlorosilane

Conditions
Conditions Yield
at 1000 ℃;
Conditions
Conditions Yield
at 499.84 - 799.84 ℃; under 800.33 Torr; Gas phase; Pyrolysis;
Conditions
Conditions Yield
With hydrogen; at 100 ℃; under 60 - 600 Torr; Product distribution; Kinetics; Thermodynamic data; labelled with tritium; -ΔH; without hydrogen;

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