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Volumn 73, Issue 5, 2008, Pages 1830-1841

The unusual reaction of semiquinone radicals with molecular oxygen

Author keywords

[No Author keywords available]

Indexed keywords

OXIDATION; PH EFFECTS; PHOTOLYSIS; RATE CONSTANTS; STOICHIOMETRY;

EID: 41149115180     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo7024543     Document Type: Article
Times cited : (111)

References (91)
  • 52
    • 41149111717 scopus 로고    scopus 로고
    • Another relevant reaction that causes the decay of the semiquinone radical is the disproportionation of two semiquinone radicals, •QH, to give the quinone (Q) and hydroquinone (QH2, However, this reaction (eq 9) does not affect the stoichiometric factor with respect to the trapping of a second peroxyl radical by the semiquinone (eq 8, i.e, n, 2 not necessarily as written
    • 2). However, this reaction (eq 9) does not affect the stoichiometric factor with respect to the trapping of a second peroxyl radical by the semiquinone (eq 8), i.e., n = 2 (not necessarily as written).
  • 62
    • 36449000402 scopus 로고    scopus 로고
    • These energies could, in principle, be corrected for basis set superposition error (BSSE), which may lead to slightly larger absolute energy barriers and reaction energies for the oxygen addition step. However, given that we are comparing two oxygen addition processes, inclusion of BSSE corrections is unlikely to change the relative energetics. Furthermore, it should be pointed out that there is some concern that BSSE corrections are overestimated in cases where electron correlation is well described, see: Saebø, S.; Tong, W.; Pulay, P. J. Chem. Phys. 1993, 98, 2170-2175.
    • These energies could, in principle, be corrected for basis set superposition error (BSSE), which may lead to slightly larger absolute energy barriers and reaction energies for the oxygen addition step. However, given that we are comparing two oxygen addition processes, inclusion of BSSE corrections is unlikely to change the relative energetics. Furthermore, it should be pointed out that there is some concern that BSSE corrections are overestimated in cases where electron correlation is well described, see: Saebø, S.; Tong, W.; Pulay, P. J. Chem. Phys. 1993, 98, 2170-2175.
  • 66
    • 41149088536 scopus 로고    scopus 로고
    • a = 14.8 kcal/mol, in much better agreement with the experimental value of 13.5 kcal/mol.
    • a = 14.8 kcal/mol, in much better agreement with the experimental value of 13.5 kcal/mol.
  • 67
    • 41149126264 scopus 로고    scopus 로고
    • Our calculations yield ΔS‡, 0.3 cal/(mol K) for elimination of hydroperoxyl from the O2 adduct of 1,4-semiquinone
    • 2 adduct of 1,4-semiquinone.
  • 76
    • 41149103723 scopus 로고    scopus 로고
    • 59
    • 59
  • 79
    • 41149110374 scopus 로고    scopus 로고
    • 62
    • 62
  • 80
    • 41149100333 scopus 로고    scopus 로고
    • The calculated solvent effect on the elimination of HOO• is 3.3 kcal/mol. While this is larger than the observed effect on the rate constant roughly one order of magnitude, it should be noted that in our calculations we are comparing the isolated O2-adduct in the gas phase with the O2-adduct H-bonded to HCN in the gas phase. It is totally reasonable that this would be overestimated relative to the O2 adduct H-bonded to chlorobenzene compared to the O2-adduct H-bonded to acetonitrile in our experiments
    • 2-adduct H-bonded to acetonitrile in our experiments.
  • 85
    • 41149099828 scopus 로고    scopus 로고
    • 2 = 0.37 for the reaction intermediate, in excellent agreement with the values obtained in the present work. In that paper a somewhat similar reaction mechanism was also tentatively suggested, i.e., a cyclic transition state with the oxygen complexed to the π system of the aromatic ring. We thank Dr. Peter Mulder for pointing out this reference.
    • 2 = 0.37 for the reaction intermediate, in excellent agreement with the values obtained in the present work. In that paper a somewhat similar reaction mechanism was also tentatively suggested, i.e., a cyclic transition state with the oxygen complexed to the π system of the aromatic ring. We thank Dr. Peter Mulder for pointing out this reference.
  • 91
    • 41149154675 scopus 로고    scopus 로고
    • Frisch, M. J, Trucks, G. W, Schlegel, H. B, Scuseria, G. E, Robb, M. A, Cheeseman, J. R, Montgomery, J. A, Jr, Vreven, T, Kudin, K. N, Burant, J. C, Millam, J. M, Iyengar, S. S, Tomasi, J, Barone, V, Mennucci, B, Cossi, M, Scalmani, G, Rega, N, Petersson, G. A, Nakatsuji, H, Hada, M, Ehara, M, Toyota, K, Fukuda, R, Hasegawa, J, Ishida, M, Nakajima, T, Honda, Y, Kitao, O, Nakai, H, Kiene, M, Li, X, Knox, J. E, Hratchian, H. P, Cross, J. B, Bakken, V, Adamo, C, Jaramillo, J, Gomperts, R, Stratmann, R. E, Yazyev, O, Austin, A. J, Cammi, R, Pomelli, C, Ochterski, J. W, Ayala, P. Y, Morokuma, K, Voth, G. A, Salvador, P, Dannenberg, J. J, Zakrzewski, V. G, Dapprich, S, Daniels, A. D, Strain, M. C, Farkas, O, Malick, D. K, Rabuck, A. D, Raghavachari, K, Foresman, J. B, Ortiz, J. V, Cui, Q, Baboul, A. G, Clifford, S, Cioslowski, J, Stefanov, B. B, Liu, G, Liashenko, A, Piskorz, P, Komaromi, I, Martin, R. L, Fox, D. J, Keit
    • Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Kiene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, Revision C.02; Gaussian, Inc.: Wallingford, CT, 2004.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.