[CONTRInUlION
PROM HIE
CIIEMICAL LADORATORY O D IOWA S1A
Organic Compounds of Uranium. VI.
COLLEGE]
Uranium(V1) Alkoxides
BY R.G. JONES, E. BINDSCHADLER, D.
BLUBIE, G. KARMAS, G. 'ITE0M.4N AND H. GILhfAN
.%. X f i z K l T N , JR., J. It. THIRTLE, F. A.
RECEIVED AUGC-ST3, 1956 Uranium( V I ) ethoxide, a dark-red, distillable liquid, was prepared by oxidation of the sodium etlioxidc complex of uranium(V) ethoxide with benzoyl peroxide. Other less efficient oxidizing agents were oxygen, bromine and lead tetraacetate. Other related uranium( VI) alkoxides were synthesized by the benzoyl peroxide method, but more conveniently they were obtained by exchange reactions between uranium(V1) ethoxide and various alcohols. The uraniurn(VT) alkoxides, although relatively volatile, were unstable toward heat. U(OC*Hb), f NcLOC~II, + NxT'(OC~H,)~~ During the early work on the preparation of uranium(V) ethoxidel a very small quantity of by- ~K'cILJ(OC?IT,)E 4- (CeIIr,CO)iO? + product in the form of a bright red liquid was often 2U(0CZ1I)E + 2SnO~CC& encountered. This red compound was usually obUranium(V1) ethoxide was a red, mobile liquid tained when oxygen was employed in the preparation of U(OGH6)s or when the latter was exposed having a density of 1.5G3. It distilled a t 74-7Go to dry air for extended periods of time. The red (0.003 mm.); 93' (0.1s rnm.). Values for the liquid was more volatile than U ( O C Z H ~and ) ~ was molecular weight, as determined by the freezing collected as a forerun during the distillation. point depression of benzene were 613 and 0. Eventually enough was obtained for characteriza- These correspond most closely with the simplest tion, and the analyses for uranium, carbon and hy- formula weight, 508, for U(OC2H5)~.Thus the drogen were consistent with the formula U(OCzH5)G. conipound appeared not to h r appreciably nssoin benzene solution. This new compound was of great interest because ciated A sample uranium(V1) ctlioxidc in a sealed of its relatively high volatility, and therefore its glass tube wasof heated a t 86' for C,G hours. During preparation and reactions were studied. Several this time it had largely decomposed. Less than related uranium(V1) alkoxides were prepared. was recovered, and the main Although in this group were found the most highly 20y0of the U(OC2Hs)6 50% yield, was U(OC2product, obtained in about volatile of the organic compounds of uranium, in general the U(0R)e derivatives were of limited H6)5. Uranium(V1) ethoxide was readily soluble stability. Even moderate heating caused decom- in such liquids as benzene, ether, petroleum ether, position, and for this reason they showed little etc. It was extremely reactive toward moisture, promise as useful substances for isotope separation. and was hydrolyzed to form uranyl hydroxide. Initially, attempts were made to convert ura- For analysis samples wcre allowed to react with nium(V) ethoxide to the uranium(V1) compound by cold, dilute sulfuric acid to yield solutions of uranyl The uranium was then determined by reaction with oxygen under various conditions. sulfate. the usual 8-hydroxyquinoline method. Although small quantities of the desired compound As expected, uranium(V1) ethoxidc was a were obtained, this method proved to be imprac- rather powerful oxidizing agent. I t was easily rctical. Other oxidizing agents such as magnesium duced to thc stable uranium(V) ethoxide by hcating peroxide, hydrogen peroxide-urea complex, chlowith ethyl diethylamine or ethyl cyanorine, iodine and nitrosyl chloride gave negative re- acetate. Amercaptan, reaction between uranium(V1) ethoxsults. Reactions of uranium(V) ethoxide with broide and uranium(1V) cthoxirle' gave uranitm(V) mine and sodium ethoxide gave low yields (5-10y0) ctho.tide. of uranium(V1) ethoxide. Better yields (about U ( O C ? F I ~+ ) ~ LJ(OC2IIj)r +2LT(0C2Hs)5 20%) were obtained by treating the sodium ethoxide salt of uranium(V) ethoxide2 with lead tetraOne mole of dry hydrogen chloride reacted with acetate. These reactions were carried out in ether uranium(V1) ethoxide to give a liquid compound or petroleum ether; in alcohol none of the tiraniuin- that appeared to have the forinula U(OC2H6)&1 (VI) compound was formed. When uranium(V1) ethoxide was treated with sodium ethoxide there was no evidence that reaction NaU(OC&)s 1/J3r?--+ U(OC2H;)G -1- h'anr took place or that a salt was formed. Alcohols NnlT(OC21T,)~ '/zE'b(OAc)r * readily entered into exchange reactions with uraU(OC?H~)G NaOAc l/d%(OAc)z nium(V1) ethoxide just as with uranium(V) ethoxide.4 The best method for the preparation of uraniumU(OC2HS)e GROH +U(OR)G OCzI3,OH (VI) ethoxide involved the use of benzoyl peroxide as oxidizing agent and ethanol as the solvent. The Presumably, a series of rnixed uranium (VI) alkoxproduct was isolated by distillation from the reac- ides like U(OR),(OR'), U(O12)3(0R')3, etc., also tion mixture and purified by fractionation under were formed in reactions of this type. With a high vacuum. Yields were 40 to GOYo based on large excess of methanol, uranimn(V1) ethoxidr uranium (V) ethoxide. reacted to form lmmium(V1) methoxide. The
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(1) I< G Jones, E. Binclschadler, 0. Karmas, r' A YrnrnTn ?nil €I GilmTn, T A IJOURNAL, ~ 78,4287 (1956). (2) K G Jones, E Rinclsclindler, D Blume. G Karmas, C; A h f v t l n , J r , T R TIiirtlP ~ n IT d Gilrnsn ibrd IS, fill27 (1056)
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(3) K G Jones, (; Ti?rni I$ (; A M n r t i n , J r , I n r l TT C:ilm7n, t b r d , 1 8 , 4285 (105G). ( 4 ) R 0 Jones, I; Bln
