Source:http://linkedlifedata.com/resource/pubmed/id/11741433
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
50
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| pubmed:dateCreated |
2001-12-19
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| pubmed:abstractText |
The photolysis reaction of di-tert-butylperoxide was studied in various solvents by photoacoustic calorimetry (PAC). This technique allows the determination of the enthalpy of this homolysis reaction, which by definition corresponds to the O-O bond dissociation enthalpy of the peroxide in solution, DHsin(degrees)(O-O). The derived value from these experiments in benzene, 156.7 +/- 9.9 kJ mol(-1), is very similar to a widely accepted value for the gas-phase bond dissociation enthalpy, DH(degrees)(O-O) = 159.0 +/- 2.1 kJ mol(-1). However, when the PAC-based value is used together with auxiliary experimental data and Drago's ECW model to estimate the required solvation terms, it leads to 172.3 +/- 10.2 kJ mol(-1) for the gas-phase bond dissociation enthalpy. This result, significantly higher than the early literature value, is however in excellent agreement with a recent gas-phase determination of 172.5 +/- 6.6 kJ mol(-1). The procedure to derive the gas-phase DH(degrees)(O-O) was tested by repeating the PAC experiments in carbon tetrachloride and acetonitrile. The average of the values thus obtained was DH(degrees)(O-O) = 179.6 +/- 4.5 kJ mol(-1), confirming that the early gas-phase result is a lower limit. More importantly, the present study questions the usual assumption that the solvation terms of homolysis reactions producing free radicals in solution should cancel, and suggests a methodology to estimate solvation enthalpies of free radicals.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Dec
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| pubmed:issn |
0002-7863
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
19
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| pubmed:volume |
123
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
12670-4
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| pubmed:dateRevised |
2003-10-31
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| pubmed:year |
2001
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| pubmed:articleTitle |
Solvation enthalpies of free radicals: O-O bond strength in di-tert-butylperoxide.
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| pubmed:affiliation |
Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8000-810 Faro, Portugal.
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| pubmed:publicationType |
Journal Article
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