6165-96-4

Upstream product

• 460-12-8 Butadiyne 
• 74-85-1 ethene 
• 593-61-3 bromoethyne 
• 624-92-0 Dimethyldisulphide 
• 74-86-2 acetylene 

Downstream Products

• 32597-32-3 decapentayne 
• 74-86-2 acetylene 

Relevant academic research and scientific papers

Scavenging of hydrocarbon radicals from flames with dimethyl-bisulfide II. Hydrocarbon radicals in fuel-rich low-pressure flames of acetylene, ethylene, 1,3-butadiene and methane with oxygen

The new technique of free-jet condensation/scavenging with dimethyl-disulfide has been applied for the quantitative analysis of hydrocarbon radicals and carbenes in flat premixed hydrocarbon/oxygen flames burning with fuel-rich mixtures at 27 mbar. The results are reported as profiles of mole fractions of the radicals. The limit of detectability was about l-10~7mole fraction. Qualitatively the radicals are very similar with the four fuels, but there are large differences in their quantities. While in the methane flame only C1 and C2 radicals were present in detectable concentration, higher radicals up to naphthyl could be detected with the unsaturated fuels. Although methyl could not be determined quantitatively, it was found to be the major hydrocarbon radical in all flames. Methoxy radical was only found in the methane flame. Whereas, for example, C2, C3H2 and C3H are typical high-temperature species, C2H is surprisingly formed at the beginning of the oxidation zone at relatively low temperature. Vinyl and the vinyl-type radicals C2nH3 (n = I to 4) are in equilibrium with acetylene and the polyynes (C2nH2) at maximum flame temperature and in the burned gas. Since phenyl peaks always after benzene, it is concluded that it is mainly a degradation product from benzene and other lower aromatics. The mechanism of formation of C2H and C2, the equilibria of the C2nH3 and the relation between aliphatic and aromatic radicals are discussed. VCH Verlagsgesellschaft mbH, 1997.

Reactions of Ethynyl Radicals with Alkynes in the System Sodium Vapour/Ethynylbromide/Alkyne

The radicals were generated from the respective halide RX by the reaction Na + RX -> R + NaX in a low-pressure flow reactor fed by a multi-slit diffusion burner.Test results are reported for the system Na/CH3I giving k(Na + CH3I) = 6.0E13 and k(CH3 + CH3) = 2.8E13 cm3 mol-1 s-1.The main part deals with the production of C2H in the system Na/C2HBr and its consecutive reactions with C2HBr and added C2H2 and C4H2.The rate constant k(Na + C2HBr) was found to be 2.9E13 cm3 mol-1 s-1.The bimolecular rate constants of C2H with the compounds above have been determined to 1.0E14, 2.3E13 and 4.0E13 cm3 mol-1 s-1, respectively, at a temperature of 603 K. - The main products in this reaction system are polyynes with a minor formation of ethyne and very little hydrogenated polyynes.The formation of an aromatic compound (ethynylbenzene) is negligibly small, a fact which is discussed in its relation to aromates in hydrocarbon flames.The primary reacion Na + C2HBr and its products are discussed as well as the unimolecular decomposition and stabilization of energized adducts formed by C2H. - Chemical Kinetics / Elementary Reactions / Flames / Radicals

SCAVENGING OF RADICALS FROM THE GAS PHASE BY FREEZING WITH DIMETHYL DISULFIDE: 2. RADICALS FROM DISCHARGES AND A FLAME OF ACETYLENE.

The method of detecting radicals from low-pressure gas-phase systems by scavenging with dimethyl disulfide (DMD) has been applied to microwave discharges in C//2H//2/He mixtures and to a C//2H//2/O//2 flame. It was accomplished by condensing a supersonic nozzle beam from the reaction system together with a beam of DMD on a liquid-N//2 cooled surface. The scavenging products were measured by GC/MS after warming-up. Radicals measured in the discharge were C//2H, C//4H, C//6H, C//3H//2, C//2 besides H atoms. Preliminary measurements on the flame showed that C//6H//5 (phenyl), CH//2, C//3H//2, besides H and O atoms were prominent radicals at the end of the oxidation zone. The concentration of phenyl is of the same order as that of e. g. naphthalene.

ANALYSE PAR SPECTROMETRIE DE MASSE DE LA STRUCTURE D'UNE FLAMME DE DIFFUSION C2H2/O2/AR

Neutral species present in C2H2/O2/Ar diffusion flame stabilized under reduced pressure (30 torrs) have been analysed by a molecular beam mass spectrometer system in order to specify the mechanism of soot formation.Comparison of the mole fraction profiles of polyacetylenic hydrocarbons and polycyclic aromatic hydrocarbons (P.A.H.) shows that the latters are considerably more reactive than the formers and hence appear as soot precursors.It was worth considering the nature of the intermediate species in the overall machanisms leading to the formation of the first aromatic rings or to an increase in the number of aromatic rings : C2H2 -> C6H6 -> H.A.P.Result suggest that C4 hydrocarbons, in particular C4H4, play an important role in these stages.

LOW-PRESSURE PYROLYSIS OF BUTADIYNE (C4H2).

Butadiyne (C//4H//2) mixed with helium (maximum 1:9) was pyrolyzed in a low-pressure flow reactor at temperatures between 700 and 1000 degree C and total pressures of 3 to 13 mbar. The residence time (maximum 45 ms) was varied by a movable inlet lance for the C//4H//2. Samples were drawn through a molecular beam system and analyzed mass-spectrometrically. The main products were C//2H//2, H//2, polyyines (C//6H//2, C//8H//2), oligomers of the composition (C//4H//2)//n, n equals 2 to 5, polymer and coke. The activation energy for oligomer formation ranged from 145 to 168 kJ mol** minus **1 increasing with higher degree of oligomerization. A mechanism for the formation of polyynes and oligomers is discussed starting with an excited C//4H//2 which can add C//4H//2 to give either a linear or a branched dimer C//8H//4. The results are compared to the formation of polycyclic aromatic compounds in the burned gas of fuel-rich flames that also contains C//2H//2 and C//4H//2.

INVESTIGATION OF THE FORMATION OF HIGH MOLECULAR HYDROCARBONS AND SOOT IN PREMIXED HYDROCARBON-OXYGEN FLAMES.

Measurements of concentrations of high molecular hydrocarbons in laminar flat low pressure flames with various hydrocarbons under sooting conditions are reported. The results show that for all fuels investigated in that region of the flames where the bulk of soot is formed besides the main combustion products some characteristic groups of species are to be found. Within these groups of species only few fuel specific characteristics are stated. The main fuel specific influence lies in the relative concentration for the species. A reaction scheme for the qualitative explanation of the results found is discussed.