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Volumn 106, Issue 37, 2002, Pages 8708-8715

Reductive dechlorination of trichloroethylene: A computational study

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSIS; CHEMICAL BONDS; COMPUTATIONAL METHODS; DECHLORINATION; DISSOCIATION; FREE RADICALS; REDUCTION; VITAMINS;

EID: 0037136630     PISSN: 10895639     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp0264073     Document Type: Article
Times cited : (44)

References (84)
  • 6
    • 0029150885 scopus 로고
    • and references therein
    • (b) Clewell, H.J.; Gentry, P.R.; Gearhart, J.M.; Allen, B.C.; Andersen, M.E. Chemosphere 1995, 31, 2561-2578 and references therein. For a debate regarding the possible carcinogenicity of TCE, see Hum. Ecol. Risk. Assess. 2001, 7, issue 4.
    • (1995) Chemosphere , vol.31 , pp. 2561-2578
    • Clewell, H.J.1    Gentry, P.R.2    Gearhart, J.M.3    Allen, B.C.4    Andersen, M.E.5
  • 7
    • 0011747014 scopus 로고    scopus 로고
    • (b) Clewell, H.J.; Gentry, P.R.; Gearhart, J.M.; Allen, B.C.; Andersen, M.E. Chemosphere 1995, 31, 2561-2578 and references therein. For a debate regarding the possible carcinogenicity of TCE, see Hum. Ecol. Risk. Assess. 2001, 7, issue 4.
    • (2001) Hum. Ecol. Risk. Assess. , vol.7 , Issue.4
  • 31
    • 0011776033 scopus 로고    scopus 로고
    • note
    • The electron affinity as well as the relative stability of the lowest-lying A′ and A″ states depends dramatically on the level of theory chosen. Calculations using either the Becke3LYP or the BHandHLYP functionals or the UCCSD(T) method have been performed in combination with several different basis sets to explore this point to some degree (Supporting Information, Table 5). From these results, it appears that basis sets including a large number of diffuse functions prefer the A′ state (e.g., at B3LYP/aug-cc-pVTZ), whereas the opposite is true for more compact basis sets (e.g., at UCCSD/T)/cc-pVTZ).
  • 47
    • 0011712793 scopus 로고    scopus 로고
    • note
    • The estimate of slightly different reduction potentials for dissociative electron transfer to TCE producing cis- or trans-dichloroethenyl radicals in ref 27 is based on different values for Henry's constant while assuming identical heats of formation. Although we arrive at a similar overall conclusion with respect to more facile reduction to the cis-dichloroethenyl radical, our conclusion is based on significantly different energies/enthalpies for the gas-phase species.
  • 53
    • 0011712503 scopus 로고    scopus 로고
    • note
    • Cob(II)alamin, formed after one-electron donation in the dissociative electron transfer to TCE, is not included in the optimized geometries shown in Figure 1. The relative energies of 12 and 15 might very well be modulated by its presence to bring the energy difference closer to that observed for 4 and 5.
  • 60
    • 0011742154 scopus 로고    scopus 로고
    • February
    • National Institute of Standards and Technology; Standard Reference Database 69 (February 2000).
    • (2000) Standard Reference Database , vol.69
  • 69
    • 0011747017 scopus 로고    scopus 로고
    • note
    • 31,55.
  • 70
    • 0000494566 scopus 로고
    • a of the methanol radical is 10.6; Henglein, A. Adv. Electroanal. Chem. 1976, 9, 163), and a strongly reducing ketyl radical anion may be formed (E° ≈ -2.5 V for the isopropyl ketyl radical anion; Wardman, P. J. Phys. Chem. Ref. Data 1989, 18, 1691). This ketyl radical anion may then be the reducing agent that converts the vinyl radicals to their anions. It should be noted that the possibly artificially increased percentage of products derived from anions did not alter the high selectivity for cis products in these studies.
    • (1976) Adv. Electroanal. Chem. , vol.9 , pp. 163
    • Henglein, A.1
  • 71
    • 0011776115 scopus 로고
    • a of the methanol radical is 10.6; Henglein, A. Adv. Electroanal. Chem. 1976, 9, 163), and a strongly reducing ketyl radical anion may be formed (E° ≈ -2.5 V for the isopropyl ketyl radical anion; Wardman, P. J. Phys. Chem. Ref. Data 1989, 18, 1691). This ketyl radical anion may then be the reducing agent that converts the vinyl radicals to their anions. It should be noted that the possibly artificially increased percentage of products derived from anions did not alter the high selectivity for cis products in these studies.
    • (1989) J. Phys. Chem. Ref. Data , vol.18 , pp. 1691
    • Wardman, P.1
  • 72
    • 0011775417 scopus 로고    scopus 로고
    • note
    • A second possible source of chloroacetylene would be from chloroethenylcobalamins. See refs 44 and 45.
  • 82
    • 0011713788 scopus 로고    scopus 로고
    • note
    • Similar to the product distribution from ethenyl radicals, the ratio of the products derived from vinyl anions will be dependent on the barriers of interconversion and protonation. However, the latter is expected to be relatively low compared to the high interconversion energy barrier.
  • 83
    • 84889546324 scopus 로고    scopus 로고
    • in press
    • 12-catalyzed dechlorination of PCE and TCE. If thc cis and trans radicals have similar reduction potentials, then the high interconversion barrier for 26 and 27 maintains overall cis selectivity. However, if the reduction potential for trans radical 5 is significantly different from that for cis radical 4 and the reduction of the radicals to their anions is significantly faster than other transformations of these species, then the final product ratio is solely dependent on the relative reduction potentials of 4 and 5. Such selective reduction of isomeric radicals has, in fact, been reported to determine the product ratio in the reductive dechlorination of 1,1,2,2-tetrachloroethane: Arnold, W.A.; Winget, P.; Cramer, C.J. Environ. Sci. Technol., in press.
    • Environ. Sci. Technol.
    • Arnold, W.A.1    Winget, P.2    Cramer, C.J.3


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.