- Gas-phase chemistry of dihydromyrcenol with ozone and OH radical: Rate constants and products
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A bimolecular rate constant, kOH+dihydromyrcenol, of (38±9) × 10-12 cm3 molecule-1 s-1 was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with 2,6-dimethyl-7-octen-2-ol (dlhydromyrcenol,) at 297± 3 K and 1 atm total pressure. Additionally, an upper limit of the bimolecular rate constant, & kO3+dihydromyrcenol, of approximately 2 × 10-18 cm3 molecule-1 s-1 was determined by monitoring the decrease in ozone (O 3) concentration in an excess of dihydromyrcenol. To more clearly define part of dihydromyrcenol's indoor environment degradation mechanism, the products of the dihydromyrcenol + OH and dihydromyrcenol + O3 reactions were also investigated. The positively identified dihydromyrcenol/OH and dihydromyrcenol/O3 reaction products were acetone, 2-methylpropanal (O=CHCH(CH3)2), 2-methylbutanal (O=CHCH(CH3)CH2CH3), ethanedial (glyoxal, HC(=O)C(=O)H), 2-oxopropanal (methylglyoxal, CH3C(=O)C(=O)H). The use of derivatizing agents O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) clearly indicated that several other reaction products were formed. The elucidation of these other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible dihydromyrcenol/OH and dihydromyrcenol/O3 reaction mechanisms based on previously published volatile organic compound/OH and volatile organic compound/O3 gas-phase reaction mechanisms.
- Forester, Crystal D.,Ham, Jason E.,Wells
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- Toward the rhodium-catalyzed bis-hydroformylation of 1,3-butadiene to adipic aldehyde
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The effects of the ligand to metal ratio, temperature, syngas pressure, partial pressures of H2 and CO, and new ligand structures have been examined on 12 of the most reasonable products resulting from the rhodium-catalyzed low-pressure hydroformylation of 1,3-butadiene. The selectivity for the desired linear dihydroformylation product, 1,6-hexanedial (adipic aldehyde), is essentially independent of all of these reaction parameters, except for ligand structure. However, the reaction parameters do have a substantial effect on the selectivity for the products, resulting from the branched addition of the rhodium hydride to the carbon-carbon double bond. The optimum reaction parameters and ligand have resulted in a so far unprecedented maximum selectivity of 50% for adipic aldehyde.
- Smith, Stuart E.,Rosendahl, Tobias,Hofmann, Peter
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experimental part
p. 3643 - 3651
(2011/09/20)
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- Visible Light Induced Reactions of NO2 with Conjugated Dienes in a Low-Temperature Ar Matrix
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Visible light induced oxygen atom transfer from NO2 to conjugated dienes has been investigated in a low-temperature Ar matrix, where the dienes are 1,3-butadiene (BD), 2-methyl-1,3-butadiene (isoprene), and 2,3-dimethyl-1,3-butadiene (DMB).In each diene/NO2/Ar system, the corresponding nitrite radical, oxirane, aldehyde, and NO were obtained as the photochemical reaction products.The reactions are initiated by the formation of undetecteable short-lived oxirane biradical and NO due to visible light induced O atom transfer from NO2 to the conjugated dienes. (1) The recombination of oxirane biradicals and neighboring NO gives the nitrite radicals as the photochemical intermediate. (2) The ring closure of the biradicals leads to the formation of oxiranes. (3) The intramolecular H atom transfer of biradicals leads to the formation of aldehydes.The visible photolysis of the nitrite radicals gives rise to oxirane, aldehyde, and NO.The reaction rates are derived by measuring the absorbance changes of the products upon the 582-nm irradiation.The methyl substituent effect on the reactivity is discussed.
- Tanaka, Nobuaki,Kajii, Yoshizumi,Shibuya, Kazuhiko,Nakata, Munetaka
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p. 7048 - 7053
(2007/10/02)
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