Photochemistry of 1,2,3‐indanetrione*

Abstract

The photochemistry of 1,2,3‐indanetrione (1) has been examined in solution at room temperature by steady state and laser flash photolysis. The triplet state of 1 (T = 6.5 μs, δmux, = 360 and 570 nm, in dry acetonitrile) reacts preferentially via an a‐cleavage process followed by a considerably slower loss of carbon monoxide. Triplet 1 shows a remarkably fast hydrogen abstraction rate constant when in the presence of 1,4‐cyclohexadiene (kr= 1.4 times 106M−1s−1) in spite of its low excitation energy (ET= 42 kcal/mol). This behavior can be explained by assuming that the vicinal carbonyls coplanar to the ketyl radical play an important role in its stabilization.

Laser flash photolysis study of the photoenols generated from ortho-benzylbenzophenone in different solvents

“…Suitably substituted aromatic ketones can form the corresponding benzocyclobutenols in fairly high quantum yields, suggesting that intramolecular [2+2] cycloaddition may be a more common process in photoen01 chemistry than had been previously assumed (6)(7)(8)(9). Other examples include chloride elimination from a-chloro acetophenones with the concomitant formation of 1-indanones (10)(11)(12), the formation of 3-phenylphthalide from the photolysis of ortho-benzoylbenzaldehyde (13), and, finally, the synthesis of 2-hydroxy-2-alkyl(or ary1)-1-indanones from ortho-alkyl substituted aromatic a-diketones (14)(15)(16)(17)(18) ysis and product studies on the photoenols in different solvents, generated by irradiation of ortho-benzylbenzophenone (1).…”

Laser flash photolysis study of the reaction of 1H-benz[f]indane-1,2,3-trione with olefins

“…Similar behavior, i.e., large quenching rate constants for cyclic vicinal triketones of low triplet energy by 1,3-cyclohexadiene, was previously observed for 1,2,3-indanetrione (2, R=H) and its 5-methoxy derivative 3, R=OMe. 4,8 To further confirm the triplet nature of the transient observed in Figure 1, quenching experiments employing -carotene were undertaken. -Carotene shows triplet energy of 79 kJ mol -1 9 and has intersystem crossing quantum yield of essentially zero.…”

Fotoquímica de alfa,alfa-dimetilvalerofenona adsorvida em celulose microcristalina

“…O efeito catalítico resulta de uma interação entre catalisador e substrato, sendo esta interação explicada com base em suas geometrias. Tais observações têm sugerido investigações acerca da formação de complexos entre cetonas e carboidratos; por ex., foi mostrado que amostras liofilizadas contendo β-fenilpropiofenona e mono-, di-ou polissacarídeos (glicose, maltose, frutose, galactose, sacarose e celulose) emitem fosforescência 1,2 , da mesma forma que quando incluídas em ciclodextrinas 3 . Celulose tem sido largamente utilizada para obtenção de espectros de emissão de fosforescência à temperatura ambiente de diversos compostos, mesmo em presença de oxigênio molecular 4,5 .…”