ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS

Time resolved near IR luminescence detection of singlet oxygen, O2(¹deltag), and steady-state photolysis experiments were performed to study in detail limitations and approaches involved when 9,10-dimethylanthracene (DMA) is used as actinometer to measure the chemical rate constants, kr, for the rea...

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Autores principales:	Günther S.,Germán, Lemp M.,Else, Zanocco,Antonio L.
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2000
Materias:	9,10-Dimethylanhracene Singlet Oxygen Actinometry Photo-oxidations Chemical Rate Constant
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442000000400018
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spelling	oai:scielo:S0366-164420000004000182001-05-25ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONSGünther S.,GermánLemp M.,ElseZanocco,Antonio L. 9,10-Dimethylanhracene Singlet Oxygen Actinometry Photo-oxidations Chemical Rate Constant Time resolved near IR luminescence detection of singlet oxygen, O2(¹deltag), and steady-state photolysis experiments were performed to study in detail limitations and approaches involved when 9,10-dimethylanthracene (DMA) is used as actinometer to measure the chemical rate constants, kr, for the reaction between excited oxygen and a given substrate. Our results show that in solvents in which singlet oxygen lifetime is long, the actinometer opens an additional pathway to the singlet oxygen disappearance at a rate of similar magnitude to the decay rate constant of O2(¹deltag), kdelta. This reactive pathway decreases singlet oxygen concentration. In this case erroneous values of the chemical reaction constant, k rM, for the reaction between singlet oxygen and a given substrate M will be obtained. Additionally, we have found that not in all the solvents, can the total rate constant, kT DMA, for the reaction between singlet oxygen and 9,10-dimethylanthracene obtained from time resolved experiments be taken as the "reactive" rate constant, k rDMA, when DMA is employed as an actinometer. The chemical reaction constant, k rM, for the reaction between singlet oxygen and a given substrate M obtained in these conditions will be smaller than the true values. Then, to employ DMA as actinometer, kT DMA and k rDMA must be previously evaluated. If kT DMA and k rDMA values are very close, nearly ideal conditions to employ DMA as actinometer are fulfilled. Moreover, if kTDMA and krDMA differ in a greater extent, further corrections must be applied to improve k rM values.info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaBoletín de la Sociedad Chilena de Química v.45 n.4 20002000-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442000000400018en10.4067/S0366-16442000000400018
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	9,10-Dimethylanhracene Singlet Oxygen Actinometry Photo-oxidations Chemical Rate Constant
spellingShingle	9,10-Dimethylanhracene Singlet Oxygen Actinometry Photo-oxidations Chemical Rate Constant Günther S.,Germán Lemp M.,Else Zanocco,Antonio L. ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
description	Time resolved near IR luminescence detection of singlet oxygen, O2(¹deltag), and steady-state photolysis experiments were performed to study in detail limitations and approaches involved when 9,10-dimethylanthracene (DMA) is used as actinometer to measure the chemical rate constants, kr, for the reaction between excited oxygen and a given substrate. Our results show that in solvents in which singlet oxygen lifetime is long, the actinometer opens an additional pathway to the singlet oxygen disappearance at a rate of similar magnitude to the decay rate constant of O2(¹deltag), kdelta. This reactive pathway decreases singlet oxygen concentration. In this case erroneous values of the chemical reaction constant, k rM, for the reaction between singlet oxygen and a given substrate M will be obtained. Additionally, we have found that not in all the solvents, can the total rate constant, kT DMA, for the reaction between singlet oxygen and 9,10-dimethylanthracene obtained from time resolved experiments be taken as the "reactive" rate constant, k rDMA, when DMA is employed as an actinometer. The chemical reaction constant, k rM, for the reaction between singlet oxygen and a given substrate M obtained in these conditions will be smaller than the true values. Then, to employ DMA as actinometer, kT DMA and k rDMA must be previously evaluated. If kT DMA and k rDMA values are very close, nearly ideal conditions to employ DMA as actinometer are fulfilled. Moreover, if kTDMA and krDMA differ in a greater extent, further corrections must be applied to improve k rM values.
author	Günther S.,Germán Lemp M.,Else Zanocco,Antonio L.
author_facet	Günther S.,Germán Lemp M.,Else Zanocco,Antonio L.
author_sort	Günther S.,Germán
title	ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
title_short	ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
title_full	ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
title_fullStr	ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
title_full_unstemmed	ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS
title_sort	on the use of 9,10-dimethylanthracene as chemical rate constant actinometer in singlet molecular oxygen reactions
publisher	Sociedad Chilena de Química
publishDate	2000
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442000000400018
work_keys_str_mv	AT gunthersgerman ontheuseof910dimethylanthraceneaschemicalrateconstantactinometerinsingletmolecularoxygenreactions AT lempmelse ontheuseof910dimethylanthraceneaschemicalrateconstantactinometerinsingletmolecularoxygenreactions AT zanoccoantoniol ontheuseof910dimethylanthraceneaschemicalrateconstantactinometerinsingletmolecularoxygenreactions
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ON THE USE OF 9,10-DIMETHYLANTHRACENE AS CHEMICAL RATE CONSTANT ACTINOMETER IN SINGLET MOLECULAR OXYGEN REACTIONS

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