Nitrobenzaldehydes, photolysis

Figure IX-L-12. 2-Nitrobenzaldehyde photolysis frequencies as a function of solar zenith angle for clear lower tropospheric skies at 0.5 km altitude and an ozone column of 350 DU the results shown were calculated using the measured solution phase cross sections, and a quantum yield of photoisomerization of 0.5 figure from Calvert et al. (2002).

Recently George and Scaiano [12] examined the reaction of Ciamician and Silber and came to the conclusion that photolysis of o-nitrobenzaldehyde proceeded by a triplet state with a life-time of 0.6 ns. Laser flash photolysis showed the formation of a transient intermediate according to (3) ... 

Nanosecond laser photolysis and conductimetric detection have been used to show that the photoisomerisation of 4-nitrobenzaldehyde to 4-nitrosobenzoic acid in aqueous solution occurs via the mechanism in Scheme 4 The... 

Thiochromanones, on photolysis (350 nm) in methanol, undergo not photoisomerization, such as is observed with 4-isothiochromanones, but photodehydrogenation to 4-thiochromones in moderate (50—55%) yield. 2-(t-Butylthio)-benzaldehyde (177), prepared in near quantitative yield from 0-nitrobenzaldehyde as indicated in Scheme 40, is a useful new synthon for thiocoumarins (178 R = CO2H, CONH2, C02Et, CN, Bz, Ph, or 2-thienyl) and benzo[l,2-f> 5,4-f> ]bisthiopyrans (179). ... 

Nitrobenzaldehydes have not been reported as products of the atmospheric oxidation of toluene, but these compounds could conceivable be formed through the oxidation of toluene in an NOjc-rich atmosphere. o-Nitrobenzaldehyde has been used successfully as an actinometer in photochemical studies (Pitts et al., 1964), and in this sense a brief discussion of its photochemistry is given here. The photochemistry of o-nitrobenzaldehyde has been studied in acetone and ligroin solutions (Leighton and Lucy, 1934a, b), in the pure solid (Bowen et al., 1924), and in KBr matrices (Pitts et al., 1964). Photolysis results in the ultimate isomerization to o-nitrosobenzoic acid, stmcture C (reaction mechanism IX-L-5). 

IX-L-5.3. Photolysis Frequencies for the Photodecomposition of 2-Nitrobenzaldehyde in the Lower Troposphere... 

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