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Low-temperature chlorination of uranium metal in the TBP3TCE3Cl 2 systems was studied. Dissolution of uranium in the dipolar aprotic solvent proceeds with formation of U(IV) compounds. The activation energy of this process is 31.24 kJ mol !1 , and relative reaction order with respect to Cl 2 is 2. The effect of TBP concentration on chlorination was examined. The chlorination rate sharply increases at a water content in the TBP3TCE system of 0.23 0.6 vol %.Oxidative dissolution of metals in nonaqueous solutions shows much promise for preparing complexes and developing novel procedures for processing of raw materials [1,2]. Oxidative dissolution of uranium metal in nonaqueous solvents is studied poorly. Only the reactions of uranium metal with bromine and iodine in donor solvents [335] and oxidation of uranium metal with a solution of bromine in ethyl acetate [6] were studied. Published data on the use of such strong and available oxidant as chlorine are lacking.In this study we examined the kinetic relationships of the oxidative dissolution of U metal in solutions of tributyl phosphate (TBP) in tetrachloroethylene (TCE) in the course of low-temperature nonaqueous chlorination.In our work we used chemically pure grade TBP which was pretreated according to the procedure given in [7] and TCE purified by distillation [7].The dissolution experiments were performed in a temperature-controlled reactor using the rotating disc procedure (800 3900 rpm). According to preliminary experiments the dissolution under these conditions is kinetically controlled. The sample of uranium metal was preliminarily polished and degreased.We studied the dissolution of uranium metal in the TBP (30 vol %)3TCE (70 vol %)3Cl 2 system at various concentrations of Cl 2 (Fig. 1).The UV spectra of the resulting solutions suggest formation of UCl 4 complexes. Previously we showed that the reaction of UCl 4 with TBP in nonaqueous solutions yields the complex UCl 4 . 2TBP [8]. The nonaqueous chlorination in TBP solution can be described by the following equation: TBP U + 2Cl 2 (sol.) 76 UCl 4 (sol.) . 2TBP.(1)The data given in Fig. 1 were treated using the Microsoft Excel software. The specific rate of dissolution of uranium metal at the initial moment was calculated; the dependence of this rate on the chlorine concentration is shown in Fig. 2.The relative order of reaction (1) with respect to chlorine is 2, and the reaction rate constant k 0 is 100.83 mg cm min 31 mol 31 .Thus, the dependence of the specific rate of dissolution of uranium metal on the chlorine concentraFig. 1. Dissolution of U metal in the TBP (30 vol %)3TCE (70 vol %)3Cl 2 system at 50oC as influenced by the initial concentration of chlorine (M): (1) 1.55, (2) 1.0, (3) 0.7, (4) 0.5, and (5) 0.3.

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