2005
Photodecarbonylation of Dibenzyl Ketones and Trapping of Radical Intermediates by Copper(II) Chloride in Frozen Aqueous Solutions
RŮŽIČKA, Radovan, Lenka BARÁKOVÁ a Petr KLÁNZákladní údaje
Originální název
Photodecarbonylation of Dibenzyl Ketones and Trapping of Radical Intermediates by Copper(II) Chloride in Frozen Aqueous Solutions
Název česky
Photodecarbonylation of Dibenzyl Ketones and Trapping of Radical Intermediates by Copper(II) Chloride in Frozen Aqueous Solutions
Autoři
RŮŽIČKA, Radovan (203 Česká republika), Lenka BARÁKOVÁ (203 Česká republika) a Petr KLÁN (203 Česká republika, garant)
Vydání
Journal of Physical Chemistry B, USA, The American Chemical Society, 2005, 1089-5639
Další údaje
Jazyk
angličtina
Typ výsledku
Článek v odborném periodiku
Obor
10403 Physical chemistry
Stát vydavatele
Spojené státy
Utajení
není předmětem státního či obchodního tajemství
Impakt faktor
Impact factor: 2.898
Kód RIV
RIV/00216224:14310/05:00012596
Organizační jednotka
Přírodovědecká fakulta
UT WoS
000229134000024
Klíčová slova anglicky
photochemistry; ice; debenzyl ketone
Štítky
Příznaky
Mezinárodní význam
Změněno: 23. 6. 2009 15:27, prof. RNDr. Petr Klán, Ph.D.
V originále
This paper presents a quantitative and qualitative study of the Norrish type I reaction of dibenzyl ketone(DBK) and 4-methyldibenzyl ketone (MeDBK), producing the benzyl radicals and consequently recombination products, in frozen aqueous solutions over a broad temperature range (-80 to 20 oC). This work extends previous research on the cage effects in various constrained media to provide information about the dynamics and reactivity of the photochemically generated intermediates at the grain boundaries of ice matrix. As the temperature of aqueous solutions decreases, the solute concentrations become high at layers covering ice crystals, causing efficient molecular segregation. The cage effect experiments have shown that diffusion of the benzyl radicals within such reaction aggregates is still remarkably efficient at temperatures below -50 oC, independently of the initial ketone concentration in the range of 10(-6)to -10(-4) mol L(-1). In addition, the study of trapping the benzyl radicals formed in situ by CuCl2 was used as a qualitative probe of heterogeneous bimolecular reactions in the frozen aqueous matrix and on its surface. Molecules of both solutes were found to be segregated from the ice phase to the same location and underwent chemical reactions within diffusion and intermediates lifetimes limits. Understanding the fundamental physicochemical processes in ice is unquestionably important in related environmental or cosmochemical investigations.
Česky
This paper presents a quantitative and qualitative study of the Norrish type I reaction of dibenzyl ketone(DBK) and 4-methyldibenzyl ketone (MeDBK), producing the benzyl radicals and consequently recombination products, in frozen aqueous solutions over a broad temperature range (-80 to 20 oC). This work extends previous research on the cage effects in various constrained media to provide information about the dynamics and reactivity of the photochemically generated intermediates at the grain boundaries of ice matrix. As the temperature of aqueous solutions decreases, the solute concentrations become high at layers covering ice crystals, causing efficient molecular segregation. The cage effect experiments have shown that diffusion of the benzyl radicals within such reaction aggregates is still remarkably efficient at temperatures below -50 oC, independently of the initial ketone concentration in the range of 10(-6)to -10(-4) mol L(-1). In addition, the study of trapping the benzyl radicals formed in situ by CuCl2 was used as a qualitative probe of heterogeneous bimolecular reactions in the frozen aqueous matrix and on its surface. Molecules of both solutes were found to be segregated from the ice phase to the same location and underwent chemical reactions within diffusion and intermediates lifetimes limits. Understanding the fundamental physicochemical processes in ice is unquestionably important in related environmental or cosmochemical investigations.
Návaznosti
| GA205/05/0819, projekt VaV |
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| MSM0021622412, záměr |
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| SB/660/01/03, projekt VaV |
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