The Photochemical Reaction of α-Diketones

Abstract

The relative photochemical reactivity of α-diketones, in particular, 9,10-phenanthraquinone, 1,2-naphthoquinone, acenaphthoquinone, benzil, 4,4′-dimethylbenzil, 2,4,6-trimethylbenzil, 2,5,2′,5′-tetramethylbenzil, 2,3,5,6-tetramethylbenzil, 2,4,6,2′,4′,6′-hexamethylbenzil, phenylglyoxal, 2,5-dimethylphenylglyoxal, and 2,4,6-trimethylphenylglyoxal was investigated in hydrogen donating solvents. Type of the product and relative reactivity differ widely according to the structure of α-dike tones. Whereas 9,10-phenanthraquinone gives 1,4-adduct (V) in a hydrogen donating solvent (THF), 2,5,2′,5′-tetramethylbenzil gives 2-hydroxy-2-(2′,5′-dimethylphenyl)indanone (VII) via intramolecular hydrogen abstraction in nearly quantitative yield. No photochemical reaction of 2,4,6-trimethylbenzil or 2,3,5,6-tetramethylbenzil could be observed in the same solvent even under a long irradiation.

Photochemical Reaction Between 1,2‐Naphthoquinone and Adenine in Binary Water‐Acetonitrile Solutions

“…The further HA leads to formation of 1,2-dihydroxynaphthalene (NQ +2H ). As suggested by Kuhmet al (40,41), the absorption at 420 nm is attributed to the contribution of NQ +2H as the HA product of photo-excited NQ in the absence of oxygen. As shown in Fig.…”

Kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of amines and polymethylbenzenes

“…Ketols have light yellow color. 10 For instance, the elec tronic absorption spectrum of the product of the reaction of compounds 1 and 2d (9 hydroxy 9 (3´,5´ dimethyl benzyl) 10 oxo 9,10 dihydrophenanthrene) in benzene contains an unresolved band in the visible region with the red boundary at 500 nm. The molar absorption coefficient of this absorption band at λ = 410 nm is equal to 12 L mol -1 cm -1 .…”

“…9 9 Hydroxy 9 (3´,5´ dimethylbenzyl) 10 oxo 9,10 dihydro phenanthrene was synthesized according to a previously described procedure. 10 Quantum yields of photoreduction of 9,10 phenanthrene quinone in the presence of polymethylbenzenes and p substituted N,N dimethylanilines were determined using a standard acti nometer (potassium ferrioxalate). A benzene solution (4.4 mL) containing 9,10 phenanthrenequinone (1•10 -3 mol L -1 ) and a hydrogen donor (5•10 -2 mol L -1 ) was deaerated, saturated with argon, and placed in a quartz cell 1 cm thick.…”

“…The solution was irradiated with a monochromatic light of λ = 412 nm, which was isolated from the full light flux of an KGM 24 150 lamp using an interference light filter no. 10. The intensity measurement of the monochromatic light and experimental runs were carried out according to a known procedure.…”

trans,anti,trans-Tetra(spirotetrahydrofuranyl)cyclohexane-1,2-dione. Stereocontrolled Synthesis and Definition of Its Susceptibility to Photoisomerization

“…15 The two latter processes have been previously documented. 16,17 The sixth type of photorearrangement operates in bridged cyclohexenediones. Upon photoexcitation, 1,3-acyl migration is induced with the formation of unsaturated cyclobutanediones.…”