- Production of Acrylonitrile and Other Unsaturated Nitriles from Alkenes and Alkynes
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Passage of unsaturated organic molecules trough a 13.56-MHz radio-frequency discharge, in the presence of cyanogen, results in the formation of unsaturated nitriles.Acrylonitrile was the major product from ethylene, propylene, acrolein, methyl vinyl ketone, or 1,1,1-trifluoropropylene. 1-Butene, 2-butene, and isobutylene gave mixtures of nitrile products with the CN situated at vinylic or allylic positions. 2-Butyne gave 1-cyanopropyne.Other compounds gave only low yields of nitriles and considerable polymer.The effects of power, pressure, flow rate, and ratios of reactants on the yields of acrylonitrile from propylene and cyanogen were studied.A typical power yield of acrylonitrile was 30 g kW-1 h-1.Maximum material yields of nitrile products were obtained at intermediate powers and pressures.The products are consistent with a reaction scheme involving attack of initially formed cyano radicals on the organic substrate.This step forms activated radical intermediates, which decay through elimination of an atom or group.The atom or group which is most weakly bound is preferentially lost.
- Henis, Neil B.,Miller, Larry L.
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- Low temperature rate coefficients for the reactions of CN and C2H radicals with allene (CH2=C=CH2) and methyl acetylene (CH3CCH)
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Using a continuous flow CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in Uniform Supersonic Flow) apparatus, rate coefficients have been measured for the reactions of the cyanogen (CN) and ethynyl (C2H) radicals with allene (CH2=C=CH2) and methyl acetylene (CH3CCH) at temperatures from 295 down to 15 K for the reactions of CN and down to 63 K for those of C2H. All four reactions occur at rates close to the collision-determined limit. The results are compared with those obtained earlier for the reactions of other alkenes and alkynes, and, in the accompanying Letter by Vakhtin et al., with results for C2H+CH2=C=CH2 and C2H+CH3CCH obtained at 103 K using a pulsed Laval apparatus. The implications of these latest results for the chemistry of interstellar clouds and planetary atmospheres are discussed.
- Carty, David,Le Page, Valery,Sims, Ian R.,Smith, Ian W.M.
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- 3-pyridazinylnitrenes and 2-pyrimidinylnitrenes
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Mild flash vacuum thermolysis of tetrazolo[1,5-b]pyridazines 8T generates small amounts of 3-azidopyridazines 8A (8aA, IR 2145, 2118 cm-1; 8bA, 2142 cm-1). Photolysis of the tetrazoles/azides 8T/8A in Ar matrix generates 3-pyridazinylnitrenes 9, detected by ESR spectroscopy (9a: D/hc = 1.006; E/hc = 0.003 cm-1). Cyanovinylcarbenes 11, derived from 4-diazobut-2-enenitriles 10, are also detected by ESR spectroscopy (11a: D/hc = 0.362; E/hc = 0.021 cm-1). Carbenes 11 rearrange to cyanoallenes 12 and 3-cyanocyclopropenes 13. Triazacycloheptatetraenes 20 were not observed in the photolyses of 8. Photolysis of tetrazolo[1,5-a]pyrimidines/2- azidopyridmidines 18T/18A in Ar matrices at 254 nm yields 2-pyrimidinylnitrenes 19, observable by ESR, UV, and IR spectroscopy (19a: ESR: D/hc = 1.217; E/hc = 0.0052 cm-1). Excellent agreement with the calculated IR spectrum identifies the 1,2,4-triazacyclohepta-1,2,4,6-tetraenes 20 (20a, 1969 cm -1; 20b, 1979 cm-1). Compounds 20 undergo photochemical ring-opening to 1-isocyano-3-diazopropenes 23. Further irradiation also causes Type II ring-opening of pyrimidinylnitrenes 19 to 2-(cyanimino)vinylnitrenes 21 (21a: D/hc = 0.875; E/hc = 0.00 cm-1), isomerization to cyaniminoketenimine 25 (2044 cm-1), and cyclization to 1-cyanopyrazoles 22. The reaction mechanisms are discussed and supported by DFT calculations on key intermediates and pathways. There is no evidence for the interconversion of 3-pyridazinylnitrenes 9 and 2-pyrimidinylnitrenes 19.
- Torker, Sebastian,Kvaskoff, David,Wentrup, Curt
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p. 1758 - 1770
(2014/03/21)
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- Process for production of 5-amino-3-methylpyrazole
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The process for producing 5-amino-3-methylpyrazole includes the steps of reacting 2,3-dichloropropene with a cyanogenating agent in the presence of a cuprous salt and water at a pH of 3-8 to obtain at least one intermediate selected from the group consisting of 3-chloro-3-butenonitrile and 2,3-butadienenitrile; reacting the at least one intermediate with a base in the presence of water at a pH of 12.5 or above to obtain 2-butynenitrile; and reacting the 2-butynenitrile with hydrazine. This process is advantageous in that it enables the production of 5-amino-3-methylpyrazole in high yield without using any reagent which may produce fire. 5-Amino-3-methylpyrazole is a useful intermediate for medicines, agricultural chemicals, photographic chemicals, etc.
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- Process for producing 5-amino-3-methylpyrazole
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A process for producing 5-amino-3-methylpyrazole which comprises reacting hydrazine with a reaction intermediate containing at least one compound selected from the group consisting of 3-chloro-3-butenonitrile and 2,3-butadienenitrile, which intermediate is obtainable from 2,3-dichloropropene and hydrocyanic acid. A process for producing 5-amino-4-chloro-3-methylpyrazole which comprises chlorinating 5-amino-3-methylpyrazole obtainable by the above-mentioned reaction, in the presence of hydrochloric acid.
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- Reactions of Unsaturated Azides, 8. - Azidobutatriene and Azidobutenynes
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When 1-azido-4-chloro-2-butyne (11), obtained from 1,4-dichloro-2-butyne (10), is treated with sodium hydroxide in methanol, 4-ethynyl-1H-1,2,3-triazole (19) is the main product besides the two triazoles 9 and 21.On the way from 11 to 19 and 21 azidobutatriene (14) most probably acts as a short-lived intermediate leading to five-membered heterocyclic compounds as azidoallenes do.In contrast to 14, the azidobutenynes 23 and 27 are relatively stable.They mainly give 2H-azirines (24, 28) on thermolysis and photolysis. - Keywords: Azidobutatriene, ring closure of; Triazole, preparation via azidobutatriene; Azirines
- Banert, Klaus
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p. 1175 - 1178
(2007/10/02)
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