Pregled bibliografske jedinice broj: 82329
Influence of the medium on the reaction rate of the t-butoxy radical with iron(II).
Influence of the medium on the reaction rate of the t-butoxy radical with iron(II). // 10th "Tihany" Symposium on Radiation Chemistry - Book of Abstracts
Budimpešta: Hungarian Chemical Society, 2002. str. P-10 (poster, domaća recenzija, sažetak, znanstveni)
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Naslov
Influence of the medium on the reaction rate of the t-butoxy radical with iron(II).
Autori
Mihaljević, Branka ; Ražem, Dušan
Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni
Izvornik
10th "Tihany" Symposium on Radiation Chemistry - Book of Abstracts
/ - Budimpešta : Hungarian Chemical Society, 2002, P-10
Skup
10th "Tihany" Symposium on Radiation Chemistry
Mjesto i datum
Sopron, Mađarska, 31.08.2002. - 05.09.2002
Vrsta sudjelovanja
Poster
Vrsta recenzije
Domaća recenzija
Sažetak
Tert-butoxyl radicals (t-BuO·) were generated by homolytic photodecomposition of di-tert-butylperoxide (1) using ruby laser flashes at 347 nm. The reaction of t-BuO· radicals with Fe2+ (3) was studied under pseudo-first order conditions: t-BuOOt-Bu 2 t-BuO· (1) t-BuO· products (2) t-BuO· + Fe2+ t-BuO- + Fe3+ (3) The quantum yield F(Fe3+) was determined by measuring the absorbance of Fe3+ ion as [FeCl]2+ complex at 360 nm 2 ms after the flash. According to the equation (4) derived from the reaction scheme, 1/F(Fe3+) = 1/F( t-BuO·) {1+ k0/(k3[Fe2+])} (4) the rate constant k3 was obtained from the relative rate constant kr (kr=k0/k3) and the value of k0; the latter refers to the overall rate of the competing disappearance of t-BuO· radicals from the system (reaction 2), including the highest contribution of b-cleavage. The rate constant k0 was determined using diphenylmethanol instead of Fe2+. The known rate constant of the reaction of t-BuO· radical with diphenylmethanol giving ketyl radicals (6.9 ´ 106 dm3 mol-1 s-1) was applied. The quantum yield of ketyl radicals was determined by measuring the maximum of absorbance at 535 nm. At acid concentration of 0.023 mol dm-3 HCl the rate constant k3 = 3.4 ´ 108 dm3 mol-1 s-1 was determined. It was found that the relative rate constant increased with an increase of the hydrochloric acid concentration which has been ascribed to the lower stability of t-BuO· radical at higher acidity of the medium.The effect of polarity of the medium on the reaction rate (3) was also determined. Decreasing k3 in media of increasing polarity were explained by increasing of the b-scission rate of t-BuO· radical with increasing polarity of the medium.
Izvorni jezik
Engleski
Znanstvena područja
Kemija
