PULSE-RADIOLYSIS OF ARYL BROMIDES IN AQUEOUS-SOLUTIONS - SOME PROPERTIES OF ARYL AND ARYLPEROXYL RADICALS

被引：31

作者：

FANG, XW ^{[1
]}

MERTENS, R ^{[1
]}

VONSONNTAG, C ^{[1
]}

机构：

[1] MAX PLANCK INST STRAHLENCHEM,D-45413 MULHEIM,GERMANY

来源：

JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1995年 / 06期

关键词：

D O I：

10.1039/p29950001033

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Aryl radicals were generated pulse-radiolytically in aqueous solutions by reacting the solvated electron with phenyl bromide and substituted phenyl bromides. The aryl radicals react rapidly (k greater than or equal to 2.5 x 10(9) dm(3) mol(-1) s(-1)) with O-2 giving rise to arylperoxyl radicals which display: characteristic absorptions in;the visible spectrum (490-600 nm, depending on the substituent). Aryl radicals react with alcohols by H-abstraction. Making use of the strong absorptions of the arylperoxyl radicals in the visible spectrum rate constants of the reaction of the aryl radicals with various alcohols have been determined by competition kinetics [e.g. 4-methoxyphenyl: 1.1 x 10(7) (2-PrOH), 5.8 x 10(6) (EtOH), 1.1 x 10(6) (MeOH), 5.2 x 10(5) dm(3) mol(-1) s(-1) (Bu(t)OH)]. The temperature dependence of the reaction of the 4-CN-phenyl radical was studied and reaction parameters of its reaction with O-2 (A = 4 x 10(11) s(-1); E(a) = 12 kJ mol(-1)), propan-2-ol (A = 1.5 x 10(9) s(-1); E(a) = 13 kJ mol(-1)) and tert-butanol (A = 6 x 10(9) s(-1); E(a) = 25 kJ mol(-1)) determined. While most of the arylperoxyl radicals decay by second-order processes by reacting with one another and other peroxyl radicals present (k greater than or equal to 3 x 10(9) dm(3) mol(-1) s(-1)) HO- and H2N-substituted arylperoxyl radicals also decay by first-order processes. It has been noted that the reaction of 4-nitrobromobenzene with the solvated electron does not lead to the formation of an aryl radical by halide elimination.

引用

页码：1033 / 1036

页数：4

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