Kinetics of Base-Catalysed Hydrolysis and Cyclisation of Substituted Acetamide and Benzamide O-(Phenoxycarbonyl)oximes

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Title:Kinetics of Base-Catalysed Hydrolysis and Cyclisation of Substituted Acetamide and Benzamide O-(Phenoxycarbonyl)oximes
Creators:
Mindl, Jaromír
Kaválek, Jaromír
Straková, Helena
Štěrba, Vojeslav
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 64, 10, pp. 1641-1653
Uncontrolled Keywords:Reaction kinetics, Oximes, 1,2,4-Oxadiazol-5(4<i>H</i>)-ones, Cyclisations, Reaction mechanism, Amides

Abstract

The reaction kinetics of acetamide <i>O</i>-(4-nitrophenoxycarbonyl)oxime have been studied in aqueous buffers at pH 2-11. At pH &gt; 9, the pH dependence of <i>k</i><sub>obs</sub> is linear with slope 1, the cyclisation to 3-methyl-1,2,4-oxadiazol-5(4<i>H</i>)-one and 4-nitrophenol being the only reaction. At pH &lt; 7.5, the only reaction is the hydrolysis giving 4-nitrophenol and acetamidoxime. The dependence of <i>k</i><sub>obs</sub> on pH has been used to determine the rate equation and to propose the reaction mechanism. The cyclisation kinetics of substituted benzamide <i>O</i>-(phenoxycarbonyl)oximes have been studied in the pH range from 9.25 to 11. The reaction mechanism has been proposed based on the ρ constants found. In the first reaction step, the proton is split off from the NH<sub>2</sub> group; the subsequent, rate-limiting step involves simultaneous N-C bond formation and C-O bond splitting. <p>

Title:Kinetics of Base-Catalysed Hydrolysis and Cyclisation of Substituted Acetamide and Benzamide O-(Phenoxycarbonyl)oximes
Creators:
Mindl, Jaromír
Kaválek, Jaromír
Straková, Helena
Štěrba, Vojeslav
Uncontrolled Keywords:Reaction kinetics, Oximes, 1,2,4-Oxadiazol-5(4<i>H</i>)-ones, Cyclisations, Reaction mechanism, Amides
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:64
Number:10
Page Range:pp. 1641-1653
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19991641UNSPECIFIED
ID Code:1586
Item Type:Article
Deposited On:06 Feb 2009 17:10
Last Modified:06 Feb 2009 16:10

Citation

Mindl, Jaromír; Kaválek, Jaromír; Straková, Helena; Štěrba, Vojeslav (1999) Kinetics of Base-Catalysed Hydrolysis and Cyclisation of Substituted Acetamide and Benzamide O-(Phenoxycarbonyl)oximes. Collection of Czechoslovak Chemical Communications, 64 (10). pp. 1641-1653. ISSN 0010-0765

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