Projects / Programmes
Reactive intermediates in the oxidation reactions
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 |
ozone, ethers, reactive intermediates, hydrotrioxides, hydrogen trioxide, photolysis, organic halogen compounds
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)
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.