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Reactive intermediates in the oxidation reactions

Research activity

Code Science Field Subfield
1.04.04  Natural sciences and mathematics  Chemistry  Organic chemistry 

Code Science Field
P390  Natural sciences and mathematics  Organic chemistry 
P402  Natural sciences and mathematics  Photochemistry 
Keywords
ozone, ethers, reactive intermediates, hydrotrioxides, hydrogen trioxide, photolysis, organic halogen compounds
Evaluation (rules)
source: COBISS
Researchers (4)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  08337  PhD Darko Dolenc  Chemistry  Researcher  1998 - 1999  281 
2.  06138  PhD Franci Kovač  Chemistry  Researcher  1999  85 
3.  06137  PhD Božo Plesničar  Chemistry  Head  1997 - 1999  109 
4.  06061  PhD Boris Šket  Chemistry  Researcher  1997 - 1999  349 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0103  University of Ljubljana, Faculty of Chemistry and Chemical Technology  Ljubljana  1626990  23,418 
Abstract
A. We have in the past year (1998) studied the low-temperature ozonation of isopropyl methyl ether in various solvents. We found that, as in the case of isopropyl alcohol (J. Am. Chem. Soc. 1998, 120, 8005), two polyoxides were formed in all solvents investigated, i.e., the hydrotrioxide of the ether (ROOOH) and hydrogen trioxide (HOOOH). Both polyoxides were characterized by NMR (1H, 13C, and 17O NMR). Kinetic and activation parameters for the decomposition indicate a homolytic scission of the RO-OOH bond in the ether hydrotrioxide, while ''''ionic'''' pathways, involving molecules of water, are predominant in the decomposition of HOOOH. Kinetic parameters for the decomposition of HOOOH were identical with the parameters, obtained in the decomposition studies of HOOOH, we already generated in our laboratory previously by other routes. Quantum-mechanical calculations (B3LYP/6-31G*) indicate that the ozonation of isopropyl methyl ether is a radical process involving R and OOOH radicals. The ''''in cage'''' reactions of these radicals produced ROOOH and HOOOH. B. We examined photolysis of 1,2-diphenyl-2-fluoroethanone, 1-phenyl-2-(3,5-di- methoxyphenyl)-2-fluoroethanone, 1,2-diphenyl-2-fluoro-2-chloroethanone, and 1,2-diphenyl-2-bromo-2-fluoroethanone. We found that the following processes can occur: a) alpha-cleavage, connected with breaking of the C-C bond, b) beta-cleavage, connected with breaking of the C-X bond, and c) cyclization into benzo/b/furan derivative. By photolysis of 1,2-diphenyl-2-fluoroethanone as well as 1-phenyl-2-(3,5-dimethoxyphenyl)-2-fluoroethanone in acetonitrile solution, the benzofuran derivative was formed as the main product. These results suggest that alpha-cleavage as well as beta-cleavage were not present in acetonitrile solution. Kinetic as well as quantum yield measurements for these two substrates revealed that, the rates of cyclization into benzofuran derivatives are comparable in both cases. These observations suggest that the reaction pathway involves an intermediate or a transition state with a delocalized charge. We found that in the case of chloro and bromo substituted 1,2-diphenyl-2-fluoroethanones, the photolysis is strongly dependent on the solvent used.
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