Dimer Radical Cation Formation in Poly(vinylpyrenes) Studied by Pulse Radiolysis

1995 ◽  
Vol 99 (40) ◽  
pp. 14793-14797 ◽  
Author(s):  
Akira Tsuchida ◽  
Taiji Ikawa ◽  
Masahide Yamamoto ◽  
Akito Ishida ◽  
Setsuo Takamuku
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Dimer Radical Cation

Pulse radiolysis of polystyrene in cyclohexane – Effect of carbon tetrachloride on kinetic dynamics of dimer radical cation−

2006 ◽  
Vol 426 (4-6) ◽  
pp. 306-310 ◽  
Author(s):  
Kazumasa Okamoto ◽  
Takahiro Kozawa ◽  
Miyako Miki ◽  
Yoichi Yoshida ◽  
Seiichi Tagawa
Keyword(s):  
Carbon Tetrachloride ◽  
Radical Cation ◽  
Pulse Radiolysis ◽  
Dimer Radical Cation

Formation of Highly Stabilized Intramolecular Dimer Radical Cation and π-Complex of [3n]Cyclophanes (n= 3, 5, 6) during Pulse Radiolysis

2005 ◽  
Vol 109 (16) ◽  
pp. 3531-3534 ◽  
Author(s):  
Mamoru Fujitsuka ◽  
Shingo Samori ◽  
Michihiro Hara ◽  
Sachiko Tojo ◽  
Satoko Yamashiro ◽  
...  
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Π Complex ◽  
Dimer Radical Cation

Dimer radical cation of 4-thiouracil: a pulse radiolysis and theoretical study

2013 ◽  
Vol 26 (6) ◽  
pp. 510-516 ◽  
Author(s):  
K. P. Prasanthkumar ◽  
Cherumuttathu H. Suresh ◽  
C. T. Aravindakumar
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Theoretical Study ◽  
Dimer Radical Cation

Phenylalanine: Its ˙OH and SO4˙⁻-Induced Oxidation and Decarboxylation. A Pulse Radiolysis and Product Analysis Study

1993 ◽  
Vol 48 (6) ◽  
pp. 761-770 ◽  
Author(s):  
Degui Wang ◽  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Side Reactions ◽  
Intramolecular Electron Transfer ◽  
Oh Radical ◽  
Product Analysis ◽  
Water Elimination ◽  
Deprotonation Reaction ◽  
Type Radical ◽  
Radical Yield

Phenylamine has been oxidized by radiolytically generated hydroxyl and sulfate radicals, the ensuing intermediates and their reactions have been studied by pulse radiolysis and product analysis in the absence and presence of oxidants such as Fe(CN)63- and O2. Upon OH radical attack, hydroxycyclohexadienyl-type radicals are mainly formed while Η-abstraction reactions can be neglected. In the presence of Fe(CN)63- these radicals are for the most part oxidized to the corresponding tyrosines (80%), except for the ipso-OH-adduct radicals (≈ 20%). It is concluded that ˙OH-addition is almost random, but with a slight avoidance of the metaposition relative to the ortho-, para- and ipso-positions. Oxygen adds reversibly to the OH-adduct radicals (kf = 1.8 × 108 dm3 mol-1 s-1, kr = 5.4 × 104 s-1). In this case, tyrosine formation occurs by HO2˙-elimination. However, due to side reactions, tyrosine formation only reaches 52% of the OH radical yield. The tyrosine yield drops to 10% in the absence of an oxidant.Upon SO4˙⁻-attack, decarboxylation becomes a major process (33% of SO4˙⁻) alongside the production of tyrosines (43%). Here, with Fe(CN)63- as the oxidant the formation of p-Tyr (18.5%) and m-Tyr (16.5%) is preferred over o-Tyr formation (8.5%). It is believed that in analogy to other systems a radical cation is formed immediately upon SO4˙⁻-attack which either reacts with water under the formation of hydroxycyclohexadienyl-type (“OH-adduct”) radicals, or decarboxylates after intramolecular electron transfer. The radical cation can also arise indirectly through H+-catalysed water elimination from the ˙OH-adduct radicals. At pH 2 and a dose rate of 0.0046 Gy s-1 CO2 formation matches the OH radical yield when ˙OH is the attacking radical. Below pH 2, G(CO2) decreases with falling pH. This indicates the occurrence of another, unimolecular, pathway under these conditions competing effectively with decarboxylation. This appears to be a relatively slow deprotonation reaction of the carboxylprotonated phenylalanine radical cation which gives rise to the benzyl-type radical.

Sign in / Sign up

Export Citation Format

Share Document