16419-78-6Relevant articles and documents
Polyynes and cyanopolyynes synthesis from the submerged electric arc: About the role played by the electrodes and solvents in polyynes formation
Cataldo, Franco
, p. 4265 - 4274 (2007/10/03)
The products of the electric arc between graphite electrodes have been investigated by high performance liquid chromatography-diode-array detector (HPLC-DAD) analysis in various media: distilled water, liquid nitrogen, methanol, ethanol, n-hexane and benzene. In distilled water, hydrogen capped polyynes H-(CC)n-H were the unique products demonstrating that carbon is supplied by the graphite electrodes while hydrogen is supplied by the solvent plasmalysis (in this case water plasmalysis). Arcing graphite electrodes in liquid nitrogen produces cyanopolyynes: NC-(CC)n-CN demonstrating that in this case the end groups of the polyyne chains are supplied by molecular nitrogen plasmalysis caused by the electric arc. Graphite arcing in methanol and ethanol produces very clean solutions (by-products negligible or absent) of hydrogen-capped polyynes with C8H2 as the main product accounting for more than 70 mol percent of the total polyyne concentration. By replacing graphite electrodes with titanium electrodes in methanol or in ethanol, polyynes are not formed at all; only trace amounts of polycyclic aromatic hydrocarbons (PAHs) were detected. When arcing with graphite electrodes is conducted in n-hexane or in benzene, polyyne formation is accompanied by a significant production of PAH, especially in benzene. These results have been rationalized in terms of carbonization or coking tendency of a given solvent. The effect of using titanium electrodes in place of graphite electrodes has been investigated also in n-hexane and in benzene as well as the effects of very high electric current intensity employed to ignite and sustain the submerged electric arc.
Photochemistry of cyanoacetylene at 193.3 nm
Seki, Kanekazu,He, Maoqi,Liu, Renzhang,Okabe, Hideo
, p. 5349 - 5353 (2007/10/03)
Cyanoacetylene (CA) is an important minor constituent in the Titan atmosphere and is present in the interstellar medium. The absorption cross section of CA has been measured in the region from 190 to 255 nm with a resolution of 1 nm. The photochemistry of CA at 193.3 nm has been studied using a quadrupole mass spectrometer and a Fourier transform infrared spectrometer for product analysis. From the photolysis of HC3N-D2 and HC3N-CD4 mixtures and a plateau value of 0.3 for the quantum yield (QY) of DC3N (C3N + D2 → DC3N + D), it is concluded that the main dissociation process is HC3N + hv → H + C3N with a QY of 0.30 ± 0.05 and a minor process is HC3N + hv → C2H + CN with a QY equal to or less than 0.02. The remaining process is the formation of metastable CA (a triplet or carbene). The photolysis of CA induces a noticeable pressure decrease and a concomitant formation of a mist. The QY of CA disappearance is 4.5 ± 0.5, which is much higher than that of diacetylene (QY = 2.0 ± 0.5) and of acetylene (QY = 2.3). The rapid mist formation in CA may explain a haze observed in the Titan atmosphere. A detailed mist formation process is not known. The C3N radical disappears partially by C3N + HC3N → C6N2 + H and 2C3N → C6N2. To explain the formation of minor products, HCN, C2H2, HC5N, and C4N2, two processes involving an unspecified CA metastable state or states may be proposed: HC3N* + HC3N → HC5N + HCN and C4N2 + C2H2.
