Fotólise no estado estacionário e com pulso de laser de 1-benzociclanonas e de seus derivados a,a -dimetilados Steady-state and laser flash photolysis of 1 - benzocyclanones and their a,a -dimethyl derivatives
| Autor: | José Carlos Netto-Ferreira, J. C. Scaiano |
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| Jazyk: | English<br />Spanish; Castilian<br />Portuguese |
| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Química Nova, Vol 22, Iss 4, Pp 516-521 (1999) |
| Druh dokumentu: | article |
| ISSN: | 0100-4042 1678-7064 |
| DOI: | 10.1590/S0100-40421999000400010 |
| Popis: | Laser excitation of 0.01 M solutions of 1-indanone (Ia), 1-tetralone (Ib), 1-benzosuberone (Ic), and their a,a -dimethyl derivatives IIa-c, respectively, in benzene, produced transients with maximum absorption at 425 nm, and lifetimes ranging from 62 ns (IIa) to 5.5ms (Ic). Quenching studies using well known triplet quenchers such as 1,3-cyclohexadiene and oxygen demonstrated the triplet nature of these transients. In the presence of hydrogen donors, such as 2-propanol, the triplet state decay of the ketones Ia-c leads to the formation of the corresponding ketyl radicals, i.e. IIIa-c, which show absorption spectra very similar to the parent ketone, with lmax at 430 nm and lifetime in excess of 20 ms. Steady state irradiations show that the a,a -dimethyl ketones IIa and IIc form ortho-alkyl benzaldehydes probably derived from an initial a-cleavage of the corresponding triplet excited states. |
| Databáze: | Directory of Open Access Journals |
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