Fotólise no estado estacionário e com pulso de laser de 1-benzociclanonas e de seus derivados a,a -dimetilados

• Autor(a) principal: Netto-Ferreira,José Carlos
• Data de Publicação: 1999
• Outros Autores: Scaiano,J. C.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Química Nova (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421999000400010
• topic: laser flash photolysis; 1-benzocyclanones; phosphorescence; hydrogen abstraction

Laser excitation of 0.01 M solutions of 1-indanone (Ia), 1-tetralone (Ib), 1-benzosuberone (Ic), and their <FONT FACE="Symbol">a</font>,<FONT FACE="Symbol">a</font> -dimethyl derivatives IIa-c, respectively, in benzene, produced transients with maximum absorption at 425 nm, and lifetimes ranging from 62 ns (IIa) to 5.5<FONT FACE="Symbol">m</font>s (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 <FONT FACE="Symbol">l</font>max at 430 nm and lifetime in excess of 20 <FONT FACE="Symbol">m</font>s. Steady state irradiations show that the <FONT FACE="Symbol">a</font>,<FONT FACE="Symbol">a</font> -dimethyl ketones IIa and IIc form ortho-alkyl benzaldehydes probably derived from an initial a-cleavage of the corresponding triplet excited states.