Flash photolytic generation of two keto tautomers of 1-naphthol in aqueous solution: kinetics and equilibria of enolization
Benzo[ b ]cyclohexa-2,4-dien-1-one ( 4 ) and benzo[ b ]cyclohexa-2,5-dien-1-one ( 5 ), the two most stable keto tautomers of 1-naphthol ( 1 ), were generated in aqueous solution by Norrish Type II fission of 4- and 2-phenacyl-1-tetralone, respectively, and the pH–rate profiles of their enolization w...
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Published in | Photochemical & photobiological sciences Vol. 9; no. 7; pp. 901 - 907 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Cham
Springer International Publishing
01.01.2010
|
Subjects | |
Online Access | Get full text |
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Summary: | Benzo[
b
]cyclohexa-2,4-dien-1-one (
4
) and benzo[
b
]cyclohexa-2,5-dien-1-one (
5
), the two most stable keto tautomers of 1-naphthol (
1
), were generated in aqueous solution by Norrish Type II fission of 4- and 2-phenacyl-1-tetralone, respectively, and the pH–rate profiles of their enolization were measured by flash photolysis. Several isotopic exchange rates of
1
were measured in aqueous acid to determine the corresponding rate constants of ketonization. The resulting equilibrium constants for enolization are p
K
E
(
4
) = −7.1 and p
K
E
(
5
) = −6.2. The acidity constants of the carbon acids
4
and
5
, p
K
a
(
4
) = 2.1 and p
K
a
(
5
) = 3.0, were then obtained from a thermodynamic cycle using p
K
a
(
1
) = 9.25. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1474-905X 1474-9092 |
DOI: | 10.1039/c0pp00034e |