Photocatalysis by titanium complexes of the reaction of ClO4 −, ions with alcohol molecules

In the photolysis of perchloric acid solutions of titanium(IV) with additions of ethanol, the formation of titanium(III) compounds was detected. Irradiated solutions (HClO₄]=0.8 M) at 77K are characterized by an anisotropic ESR signal with parameters g ₁=1.994, g ₁=1.904, which correspond to pseudo-octahedral aqua-complexes of titanium(III). With the passage of time, the signal intensity of the titanium(III) compounds decreases, which is explained by their oxidation by ClO₄ ions. During prolonged photolysis of titanium(IV) compounds in 7 M HClO₄ with an addition of ethanol, a multicomponent signal of the paramagnetic chlorine oxide ClO₂ with parameters g _xx=2,004, a _xx(³⁷Cl)=6.0. mTl a _xx(³⁵Cl)=7,30 mTl, is recorded instead of the signal of titanium(III) compounds. Evidently ClO₂ is formed as a result of a rapid dark reaction between compounds of trivalent titanium (products of the photochemical step) and chlorate ions, which are accumulated in the solution as a result of successive photochemical and dark redox conversions of the titanium compounds, perchlorate ions, arid free radicals from the alcohol molecules. The formation of free radicals in the system was established by the ESR method after irradiation of frozen solutions.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 679–686, November–December, 1986.