Using Distonic Radical Ions to Probe the Chemistry of Key Combustion Intermediates: The Case of the Benzoxyl Radical Anion

2013 ◽  
Vol 24 (4) ◽  
pp. 493-501 ◽  
Author(s):  
Cong Li ◽  
Adrian K. Y. Lam ◽  
George N. Khairallah ◽  
Jonathan M. White ◽  
Richard A. J. O’Hair ◽  
...  
Keyword(s):  
1987 ◽  
Vol 65 (9) ◽  
pp. 2312-2314 ◽  
Author(s):  
Donald R. Arnold ◽  
Shelley A. Mines

The photosensitized (electron transfer) irradiation of several conjugated 1,1-diphenyl alkenes, in acetonitrile with 1,4-dicyanobenzene or 1-cyanonapthalene as electron accepting sensitizer and 2,6-lutidine as base, leads essentially quantitatively to tautomerization to the less stable unconjugated isomer(s). The proposed mechanism for this reaction involves formation of the alkene radical cation and sensitizer radical anion followed by deprotonation of the radical cation, reduction of the resulting radical to the ambident anion by back electron transfer from the radical anion, and reprotonation. There are several steps in this mechanism that could control the ratio of isomers. Evidence is provided that, at least in some cases, it is the relative rate of deprotonation from the isomeric radical cations that is the determining factor. This rate is influenced by the conformation of the radical cation; the carbon–hydrogen bond involved in the deprotonation step must overlap with the singly occupied molecular orbital.


1978 ◽  
Vol 56 (23) ◽  
pp. 2985-2993 ◽  
Author(s):  
Angelo Albini ◽  
Donald R. Arnold

The photosensitized (electron transfer) irradiation of cis- and trans-2,3-diphenyloxirane (1 and 2) led to cleavage of the oxirane carbon–carbon bond and subsequent formation of the carbonyl ylide. The resulting carbonyl ylides have been trapped with the dipolarophiles, acrylonitrile, maleonitrile, and fumaronitrile. The resulting isomeric tetrahydrofuran derivatives have been characterized. Sensitizers (electron acceptors) which are effective include 1,4-dicyanonaphthalene, 1,4-dicyanobenzene, dimethyl terephthalate, and methyl 4-cyanobenzoate; 1-cyanonaphthalene was not effective. The proposed mechanism involves formation and cleavage of the oxirane radical cation followed by back electron transfer from the sensitizer radical anion to give the carbonyl ylide. Electrochemical and photophysical evidence which supports the proposed mechanism was obtained.


Sign in / Sign up

Export Citation Format

Share Document