The photocatalytic decomposition of chloroform by tetrachloroaurate(III)
Document Type
Article
Publication Date
10-2009
Publisher
Springer
Abstract
Near-UV irradiation of solutions of (Bu4N)AuCl4 in aerated ethanol-stabilized chloroform causes the continuous decomposition of chloroform, as evidenced by the production of many equivalents of HCl and peroxides. At the outset of irradiation, most of the AuCl4 − is reduced to AuCl2 −, but the reduction stops and is reversed. The same experiments done in ethanol-free chloroform cause chloroform decomposition only until the irreversible reduction of the gold is complete. In deoxygenated ethanol-free chloroform, irreversible reduction to AuCl2 − is accompanied by the formation of HCl and CCl4, while the main decomposition products in deoxygenated ethanol-stabilized chloroform are HCl and C2Cl6. It is proposed that, in ethanol-free chloroform, photoreduction of AuCl4 − begins with the concerted elimination of HCl from an association complex of CHCl3 with AuCl4 −, and that ethanol suppresses{CHCl3⋅AuCl−4}{CHCl3⋅AuCl4−} complex formation, leaving a slower radical process to carry out the photoreduction of AuCl4 − in ethanol-stabilized chloroform. In the presence of oxygen, the radical process causes a build-up of CCl3OOH, which reoxidizes AuCl2 − to AuCl4 − and allows the photodecomposition of CHCl3 to continue indefinitely.
Recommended Citation
Larissa R. Cohen, Laura A. Peña, Anton J. Seidl, Janet M. Olsen, Jennifer Wekselbaum, and Patrick E. Hoggard, “The photocatalytic decomposition of chloroform by tetrachloroaurate(III)”, Monatshefte Chem. 40, 1159-1165 (2009).
