Diethyl ether uranium

Tetraallyluranium [143, 144) and tetra(2-methylallyl)-uranium(IV) [145) are prepared by the reaction of the Grignard reagents with uranium tetrachloride in diethyl ether. The PMR spectra of these temperature-sensitive compounds are listed in Table 7. The AMgXa [146) pattern exhibited by tetraallyluranium is typical of the symmetrical jr-allyl structure in Fig. 14. The spectrum of tetra-... 

Among the neutral extractants, alcohols, ethers, and ketones have been used extensively. The most fatuous example of these is the extraction of uranyl nitrate into diethyl ether, the process used in the Manhattan Project to purify the uranium... 

In the solvent extraction purification of the uranium ore concentrate, TBP is the extractant of choice although, in the past, Butex, diethyl ether and MIBK have also been used for this purpose. The uranium ore concentrate is first dissolved in nitric acid to produce a solution of uranyl nitrate from which insoluble impurities are separated. The consumption of nitric acid in this step will depend upon the nature of the concentrate, as shown in equations (104)-( 109). Many impurities... 

Organic extractants facilitate the transfer of the metal ions from the aqueous phase to the organic phase in solvent extraction. Based on the nature of the organic extractant, the metal ion, and the diluent, effective separation methods can be devised. Uranium extraction into diethyl ether from nitrate medium by salting out is perhaps one of the first uses of solvent extraction for large-scale actinide processing (9). In this case, ether not only acts as the diluent, it also acts as the extractant, which works according to the solvation mechanism (discussed below). 

Noh and Lim reported asymmetrical photodimerization of methyl anthroate [164], Irradiation of a diethyl ether solution of methyl anthroate through a uranium glass filter (X > 330 nm) gave the 1,4-10, 9 and 1,4-9, 10 cyclodimers 117 and 118 as well as the normal 9,10-10, 9 cyclodimer 116 (Scheme 35). This is the first example of intermolecular photodimerization involving the 1,4-9, 10 positions of meio-substituted anthracenes. 

Although they have been much less smdied than the range of alkoxides in the +4, +5, and +6 oxidation states, a number of amides of uranium(iv) have been made by salt-elimination reactions in solvents such as diethyl ether or THF, examples being ... 

Numerous methods have been developed for the separation of uranium from other metals on anion-exchangers, using acid media containing methanol, ethanol, acetone, diethyl ether, or dioxan [49-52]. 

Uranium may be determined in aqueous or aqueous acetone medium (50-60% acetone), or after extraction of the complex into an organic solvent [80], The uranium-thiocyanate complex may be extracted with diethyl ether, amyl alcohol, TBP in CCU, di-(2-ethylhexyl)methyl phosphonate in benzene [81], and Septonex in CHCli [82]. The use of extraction increases the selectivity of the method. 

The uranium(IV) chloride prepared by this method is dark green in color. Since it is sensitive to moisture, it should be handled in a drybox. It melts at 863 K and dissolves readily in water with decomposition. The chloride is soluble in most polar organic solvents but is insoluble in hydrocarbons and diethyl ether. Physical properties and thermochemical data for this compound have been reported ... 

The high thermal stability of the metal-carbon bond in the actinide methyl derivatives suggests that a series of alkyl derivatives can be made. This does not prove to be the case. Reaction of C1M[N(SiMe3)2]3/ where M is thorium or uranium, with either ethyllithium or trimethylsilylmethyllithium at room temperature in diethyl ether yields the metallocycle (VI) and ethane or tetramethylsilane. A mechanism for this transformation, which involves a y-proton abstraction, is shown below. 

One of the reasons that solvent extraction is so successful in separating and purifying certain elements is that the distribution coefficients of different elements between certain solvents and aqueous solutions differ enormously. Table 4.2 lists distribution coefficients observed by Furman [F2] between diethyl ether and aqueous nitrate solutions. The much higher distribution coefficient for uranium is the reason for the successful use of diethyl ether in purifying uranium. 

Uranyl nitrate containing 1 mol of boron per 100 mol of uranium is to be purified by fractional extraction with diethyl ether from a 10 N solution of ammonium nitrate. The extract is to contain no more than 1 mol of boron per million moles of uranium and is to contain 95 percent of the uranium in the feed. What are the minimum volumes of 10 N ammonium nitrate scrub solution and diethyl ether solvent needed per unit volume of feed ... 

The ability of diethyl ether to extract uranyl nitrate from aqueous solution has been known for a hundred years and was the method chosen by the Manhattan Project to purify the uranium used in the first nuclear chain reactors. This solvent has numerous disadvantages. It is very volatile, very flammable, and toxic, and it requires addition of sodium, aluminum, or calcium nitrate to the aqueous phase to enhance extractions. When solvent extraction was first applied to recovery of uranium and plutonium from irradiated fuel, other oxygenated solvents less volatile than diethyl ether that were first used were methyl isobutyl ketone, dibutyl... 

The next step in purification is separation of uranyl nitrate from the other metallic impurities in the dissolver solution by solvent extraction. Practically aU uranium refineries now use as solvent tributyl phosphate (TBP) dissolved in an inert hydrocarbon diluent. The first U.S. refinery used diethyl ether as solvent and later refineries have used methyl isobutyl ketone or organic amines, but practically all have now adopted TBP. It is nonvolatile, chemically stable, selective for uranium, and has a uranium distribution coefficient greater than unity when the aqueous phase contains nitric acid or inorganic nitrates. 

Cations that complex easily generally form stable complexes with oxygenated organic compounds, such as diethyl ether, methyl isobutyl ketone, and tributyl phosphate (TBP). The purification of uranium by solvent extraction of hexavalent uranium from nitrate solutions, with TBP forming U02(N03)2 2TBP, was described in Chap. 5. These metals are extracted most easily from aqueous solutions free of the more hi y complexing anions, such as F, P04, or S04 . 

Bis(>j -cyclopentadienyl)bis(diethylamido)uranium(IV) is a golden yellow, air-sensitive solid that is very soluble in aromatic and aliphatic solvents, as well as in THF and diethyl ether. Its H NMR spectrum, which can serve as a satisfactory check for the purity of the compound, exhibits a singlet at 6 — 13.70 ppm due to the cyclopentadienyl moiety and a quartet and a triplet at 6 8.78 and 1.54 ppm due to the CH2 and CHj moieties of the diethylamido group, respectively (CgDg, 27°C, internal standard CgDjH, shifts in ppm calculated with respect to SiMe4). 

Method I. A 250-mL, single-necked, round-bottomed flask containing a magnetic stirring bar and wrapped in foil to exclude light, is charged with 3.80 g (10 mmol) of uranium tetrachloride, 3.32 g (42 mmol) of (diethyl-amido)lithium, and 100 mL of anhydrous diethyl ether. The reaction mixture is stirred at room temperature for 30 h, then filtered, and the solvent is... 

---