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Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064

Abstract

NETTO-FERREIRA, José Carlos  and  SCAIANO, J. C.. Steady-state and laser flash photolysis of 1 - benzocyclanones and their a,a -dimethyl derivatives. Quím. Nova [online]. 1999, vol.22, n.4, pp.516-521. ISSN 0100-4042.  http://dx.doi.org/10.1590/S0100-40421999000400010.

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.

Keywords : laser flash photolysis; 1-benzocyclanones; phosphorescence; hydrogen abstraction.

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