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rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2006-4-7
pubmed:abstractText
Kinetics of 1,3-dipolar cycloaddition of a series of meta- and para-substituted diphenyldiazomethanes (DDMs) with fullerenes C60 and C70 as dipolarophiles have been investigated in toluene at 30 degrees C. Fullerene C60 was ca. 1.5 times more reactive than C70. The rate constants (k) for the primary [3 + 2] additions increased with the increase of the electron-releasing ability of the meta and para substituent. The log k/k0 values were well correlated by the Yukawa-Tsuno (Y-T) equations with the smaller negative rho values (-1.6 and -1.7 for C60 and C70) and the reduced resonance reaction constants r (0.22 and 0.17) compared to similar reactions of common acceptors, TCNE, DDQ, and chloranil (CA). The plots of log k (acceptor) versus log k (C60) as reference gave good regression equations and the slopes became larger in the order of TCNE > DDQ > CA > C70 > or = C60. The rates were also found to decrease with the increase of solvent polarity due to the ground-state solvation of fullerenes. However, the relative reactivity of these acceptors toward the unsubstituted DDM increased in the order of DDQ > C60 > or = C70 > TCNE > CA. The unexpected higher reactivity of fullerenes was interpreted in terms of the inherent steric strain by the pyramidalization of the sp2 C-atoms as well as the shorter [6,6] bonds with larger pi-electron densities.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3263
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
71
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2995-3000
pubmed:year
2006
pubmed:articleTitle
Kinetic substituent and solvent effects in 1,3-dipolar cycloaddition of diphenyldiazomethanes with fullerenes C60 and C70: a comparison with the addition to TCNE, DDQ, and chloranil.
pubmed:affiliation
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan. oshima@chem.eng.osaka-u.ac.jp
pubmed:publicationType
Journal Article