Oxalic acid photolysis

Zuo, Y., and J. Hoigne (1992), "Formation of Hydrogen Peroxide and Depletion of Oxalic Acid in Atmospheric Water by Photolysis", Env. Sci. Technol., submitted. 

Zuo, Y. and Hoigne, J. (1992) Formation of hydrogen peroxide and depletion of oxalic acid in atmospheric water by photolysis of ironm-oxalato complexes. Environ. Sci. Technol., 26, 1014-1022. 

Oxalic acid forms complexes with Fe(III) that absorb strongly from 254 to 442 nm. The absorption corresponds to a LMCT band, with smax values around 103-104 M 1 cm x. Photolysis of trisoxalatoferrate(III) (ferrioxalate, FeOx) constitutes the most used chemical actinometer the quantum yield of Fe2+ formation is high (

[Pg.349]

In the presence of an alcohol or ether the excited acetone abstracts an H atom from the carbon alpha to the 0 atom of the alcohol or ether. Similar photoreduction of perinaph-thenone (365) has been observed. However, the nature of the excited state of acetone for liquid photoreduction in these studies has not been established. Free radicals produced from photoreduction of acetaldehyde, biacetyl and acetoin in the presence of good H-atom donors have been observed by Zeldes and Livingston (216). These authors also studied the photolysis of oxalic acid and esters (366). 

Two reports on the flash photolysis of [Co(ox)3]3 in aqueous solution have been published.93 94>04 Hoffman and co-workers93 assigned the intermediate species observed in solution at pH = 6.0 to (6) in equilibrium with small amounts of (7) (Scheme 1). In the presence of excess oxalate, another species (8) could be detected. For [Cr(ox)3]3 in the presence of 3 x 10-3M oxalic acid, Cordemans... 

C2H30J- H00CC(0H)2 Photolysis of oxalic acid ethanol H2O2/ Ethanol EPR/ 308 2.00400 70Zell... 

The most intensive studies of the photolysis of uranyl complexes of carboxylic acids have been conducted on the uranyl-oxalic acid system, particularly because of its use as a chemical actinometer. The overall photochemistry occuring in the uranyl oxalate actinometer solution is summarized by the following equations ... 

There is evidence that the primary photophysical process produces a long-lived intermediate. Parker and Hatchcard detected a long-lived but reversible optical absorption on flash photolysis of a U(VI)-oxalate solution. Photolysis at 77 K of a concentrated U02 /oxalic acid system yielded an ESR signal displaying g-factor anisotropy with an average... 

Fig. 9-150. Isocratic separation of transition metals in various wines after UV photolysis. - Separator column lonPac CS5A eluant 80 mmol/L oxalic acid +...

Abstract Photooxidation of oxalic acid over a Ti02 surface in the presence of Ag and Cu " ions was studied. Reduction of metal ions and oxidation of oxalic acid were followed under irradiation of aqueous suspensions of pH 2.5-3.5. It has been demonstrated that, after the completion of silver deposition, the small metal particles on the Ti02 surface enhance the efficiency of the semiconductor by a factor of 5 for the photooxidation of oxalic acid. The photoreduction of Cu(II) also occurs. Although a small fraction of Cu(II) is reduced and deposited on TiOi under photolysis in the presence of oxygen, the photooxidation of oxalic acid is more effective in this... 

---