346
LEONARD I. XATZlN AND JAM=
C. SULLIVAN
REFERENCES (1) (2) (3) (4) (5)
DALTON, R. H.: J. Am. Chem. SOC. 67.2150 (1935). EMMETT, P. H., A N D BRUNAUER, 8 . : J. Am. Chem. SOC.66,35 (1934). FARHAS, A., AND FARKAS, L . : Trans. Faraday SOC.31, 823 (1935). JOHNSTON, H. L., BEZMAN, I . I . , A N D HOOD, C. B . : J. Am. Chem. SOC.88,2367 (1945). PUDDINGTON, I. E.: Ind. Eng. Chem., Anal. Ed. 16, 592 (1944).
THE SYSTEM URANYL NITRATE-WATER-ORGANIC SOLVENT LEONARD I. KATZIN
AND
JAMES C. SULLIVAN
Chemistry Division, Argonne National Laboratory, Chicago, Illinois Received March 6 , 1960
In 1842 the French chemist P6ligot published a description of an ether extraction process for purifying uranyl nitrate (22), and ether solution became the classical method of purification of uranyl nitrate for chemical experimentation. From solutions in ether, crystalline substances such as UO,(NO&.~HZO. (C2H&0 and U02(NOa)z~2(CzHs)z0 have been isolated (30). At low temperatures unidentified etherates have been obtained which contain, in addition to the ether, two molecules of water per molecule of uranyl nitrate (13). Aside from such etherates, uranyl nitrate hydrates containing six, three, and two molecules of water are well known. Two independent phase studies of the ternary system uranyl nitrate-water ether, made a t practically the same time (11, 16), recognize only the solid phases uranyl nitrate hexahydrate and anhydrous uranyl nitrate in the system a t ordinary temperatures. The two authors disagree as to the properties of anhydrous uranyl nitrate, as well as with other literature regarding the preparation of that substance (8, 15, 28). Since from the overall picture there exists a real doubt aa to the stability of pure UO,(NO& with no coordinated substances to stabilize the molecule (18), the published versions of the ternary system cannot be accepted without reinvestigation. The ready solubility of inorganic salts in organic solvents is still regarded aa an unusual phenomenon, on the generalization that “like dissolves like.” A salt, reportedly a very strong electrolyte (24), that has been shown to be soluble in the whole series of alcohols through amyl alcohol (6),methyl and ethyl ethers (7, 22), acetone, formic acid, acetic acid, and acetic anhydride (6), methyl and ethyl acetates (6, 19, 20), ethyl acetoacetate (17), pyridine (20), and undoubtedly a considerable number of other organic liquids, is of interest. With the suggestion from the mixed etherates that have been formed that the key may lie in solvent coordination, the system uranyl nitrate-water-organic solvent merits study for its possible contribution to the general problem of solubility relations. Investigation of this ternary system at 25’C. is reported here for a series of alcohols, ethers, and ketones.
SYSTEM URANYL NITRATE-WATER-ORGANIC
SOLVENT
347
EXPERIMENTAL
Uranyl nztratc: This was the commercially pure hexahydrate (Mallinckrodt Chemical Company). Lower hydrates were prepared by desiccation over concentrated sulfuric acid under reduced pressure. Purity was checked by combined water and uranium analysis, and found satisfactory. Solvents: Methyl isobutyl ketone was treated to remove alcoholic impuritiea and washed thoroughly with water. Diethyl ether was redistilled; all other solvents Irere xommercially pure. The ethers mere checked periodically to insure freedom from peroxides. Refractive indices of all solvents agreed satisfactofily with the values given in the literature. The purity of tertiary butyl alcohol was checked by the melting point. Procedures: Solid and liquid mixtures were equilibrated by stirring at 25OC. f 0.03”, usually for a period of approximately .1 meek. Liquid-liquid distribution mixtures were equilibrated for a few hours only. Equilibration vessels were closed to the atmosphere, and protected from strong light during the period of equilibration. Analyses were carried out on the well-known principle of “wet residues” (26). The liquid phases were sampled by pipetting from the vessel to a weighing bottle. Weighed samples were analyzed for uranium and for mater. Organic components were estimated by difference. Solid phases were dried between sheets of filter paper until moderate pressure produced only a barely perceptible wetting of the paper. One sample was weighed for uranium analysis and three samples were weighed for water analysis. To avoid difficulties from solvents immiscible with water, samples to be analyzed for uranium were made up to volume in a mixture of water and methanol. Aliquots were withdrawn, evaporated, and ignited to U308. The average deviation of duplicate determinations so made was fO.l per cent or less. When there was reason to suspect possible reaction with the solvent, or peroxide formation, nitrogen determinations by the Kjeldahl method were performed. Water was determined, using the Karl Fischer sulfur dioxide-pyridine-methanol reagent (27) and the apparatus of Zerban and Sattler (33). An excessof reagent was added, and back-titrated with standard water-in-methanol, The reagent was prepared in two parts: solution I was prepared by absorbing 192 g. of sulfur dioxide in 212.5 nil. of high-grade pyridine; solution I1 was composed of 767 ml. of methanol, 254 g. of resublimed iodine, and 425 mi. of pyridine. The reagent was standardized daily, originally against B known mixture of water and absolute methanol. Later, from the analytical results of Bryant, Mitchell, Smith, and Ashby (4),and checking the composition of the commercially pure material by analysis for sodium acetate, sodium acetate trihydrate (crystalline) was adopted as a primary standard. Superficial search of the literature shows that a similar choice had been made by others (31). The probable error of determinations on duplicate and triplicate samples from a given phase was f0.3 per cent, standardizations showing closer agreement. While this modification served well for the acetone system, with methyl isobutyl ketone analytical results a little more erratic than normal in the low-water region suggest occasionally inadequate suppression of the ketone effect.
348
LEONARD I. KATIIN AND JAMES C. SULLIVAN
Absolute methanol was prepared by treating commercial absolute methanol with e x c m magnesium metal turnings, and distilling the product with precautions to exclude moisture.
He0
FIGS.1,2. System uranyl nitrate-water-diethyl ether. A , hexahydrate and variable waterrich liquid; B, hexahydrate and two liquid phases; C, hexahydrate and variable organic-rich liquid; D, hexahydrate solid, trihydrate-monoethernte solid, and liquid; E, trihydrate-monoetherate and variable liquid; F, trihydrate-monoetherate, dihydrate-dietherate,and liquid; G , dihydrate-dietherate and variable liquid; H , dihydrate-dietherate (anhydrous dietherate?), and liquid; K, (anhydrous dietherate?) and variable liquid; L, region of separation of two liquid phases; SI, Sz, homogeneous liquid phases. RESULTS
Uranyl nitrate-wafer-diethyl ether @gures 1 and 8; table 1 ) : Contrary to the earlier reports cited (11, 16), intermediate solids are found with water contents lower than six molecules of water per uranyl nitrate. Two such solids are the uranyl nitrate trihydrate-monoetherate (30) and the dihydrate-dietherate. It is interesting that tetrssolvated uranyl nitrate crystals form with mixed solvation, while the water system does not seem to show any tetrahydrate (5, 9). 4 n anhydrous solid phase has not been obtained, but there is reason to believe
0
TABLE 1 Uranyl nitmte-water-diethyl ether ot #PC. OPGANIC PEAS1
-
__
HlO
HlO
PW 6mJ
~
pn
CItl
3
z
6 -
n cml pn cent
pn cmil
49.60 49.70
22.59 22.07
76.39 77.42
8.36 7.56 7.21 7.58
54.95 54.28 54.71 55.49
11.34 19.07 11.02 10.30
72.04 75.00 76.15 77.07
6.30 6.16
53.01 53.69
6.80 6.86
66.98 68.15
5.39 4.72
53.16 53.39
6.26 6.27
67.44 68.04
44.24 44.85 47.22
0.00 0.00 5.80 19.35 24.32 34.52 39.42 49 * 97
42.20 55.4t 55.55
9.32 9.36
8.H
1o.z 29.0l 36.2 38.44
41.93
--
HlO pn cm
1.25 1.25 1.10 2.04 4.23 5.49 7.55 7.79 8.95
94.0 83.49 80.86 68.44 59.71 56.14 51.75 53.25 44.23
DAXP SOLID
- __
-349
350
LEONARD I. KATZIN AND JAMES C. SULLIVAN
that it would be dietherate, corresponding to the dietherate reported in the older literature (30). Since both Guempel (11) and Miaciatelli (16) investigated the low-water part of the phase system with starting solid allegedly the anhydrous uranyl nitrate, and report different values of the solubility of the anhydrous material in anhydrous ether, there seems additional reason to doubt the composition of their starting solid.
FIGS.3, 4. S y s t e m diethyl cellosolve-water-uranyl
H2 0 nitrate. See legend for figures 1, 2.
A phenomenon of the aqueous phase which will be discussed in more detail later in this paper is the noticeable increase in solubility of the uranyl nitrate in the ether as one goes from the point of equilibrium of two liquid phases with the uranyl nitrate hexahydrate phase in the low-water direction. Comparison with the liquid point at which the hexahydrate solid phase commences to change composition, on the weight percentage plot (figure l), shows the effect plainly. The mole percentage plot, corroborating the effect, shows further that when the equilibrium solid has changed from the hexahydrate to solids containing less water, the mole per cent of uranyl nitrate in the liquid phase stays essentially constant, through succeeding changes of the solid phase composition. Intfpection of the phase diagrams in the region of liquid-liquid distribution
SYSTEM URANYL NITRATE-WATER-ORGANIC
SOLVENT
35 1
shows that the water content of the ether increases as its uranyl nitrate content increaaes. Analysis of the organic phase compositions (see below) shows clearly that the uranyl nitrate is extracted into the organic phase with four molecules of water attached. Uranyl nitrafe-uater-ethykne glycol diethyl ether (diethyl cellosolve) &ures 3 and 4; table 0 ) : This diether gives a picture very like that for diethyl ether. Differ-
\\%
3
0
H 20
FIG.4
a c e s are due in part to its greater water solubility and molecular weight, and
in part to the fact that in the region of liquid-liquid distribution, the uranyl nitrate extracted into the organic phase is in part associated with six molecules of water, rather than four. In the low-water region of the phase diagram, similar solid phases are found as were found with the diethyl ether. Owing either to impurities or to occasional reaction of the solute with the organic material, some aberrant liquid points were found. Another complication experienced with this solvent was slow formation in the solid phases of what was probably uranyl peroxide, owing to interaction with oxygen of the air. Uranyl nitrafe-wafer-hexyl ether Wgures 6 and 6; table 3): The phase diagram with hexyl ether was not completed, owing to formation of solid peroxide, as
352
LEONARD I. KATZLN AND JAMES C. SULLIVAN
was noted with the diethyl cellosolve. An interesting feature in the data is the striking increase in solubility of uranyl nitrate as the activity of the water in the ternary system is decreased. From a solubility of 4.5 per cent by weight at the point of triphasic equilibrium (uranyl nitrate hexahydrate and two liquid phases), the solubility rises to 18 per cent at the point a t which the solid phase changes from uranyl nitrate hexahydrate to the trihydrate. As indicated, the TABLE 2 Uranyl nitrateluater-diethy2 ce12oaoEue at #PC. AQDEOOS PEASE
ORGANIC PHASE
DAMP SOLlD
HIO
t
HIO per cw
per cen
-
g -- - __
WENTIITY O? SOLID PEASE
pnccrrl
>e? cenl
per ccnl
74.51 61.06 55.52 56.19 55.83 47.47
16.55 20.47 25.93 29.13 42.27
3.28 4.56 6.88 9.10 10.45 11.52
8.16 i7.22 24.14 29.69 43.73
39.63 39.83
54.73 55.48
12.55 12.22
53.49 54.05
11.91 10.77
54.18 55.31
10.31
54.25
17.29
74.17
6.57 6.32 6.33 6.48
45.63 45.08 45.60 46.01
8.40 7.87 7.55 7.34
66.38 67.16 66.42 61.78
5.86
48.21
5.62
57.30
pnccrrl
--
--
U02(NOn)2. ~ H z OPcellosolve .
solid phase with three molecules of water per uranyl nitrate apparently contains no organic component. This might be due t o steric effects. The solid with two molecules of water per uranyl nitrate may be either the dihydrate-dietherate, or the dihydrate-monoetherate, the data being indecisive because of analytical difficulties associated with peroxide formation. From the composition of the organic phase a t the triphasic equilibrium point, the uranyl nitrate extracted into the organic phase in the region of liquid-liquid distribution seems to be accompanied by only two molecules of water per uranyl nitrate. Uranyl n i t r a i e w @ ~ p~r e s Y and 8; tubk 4 ) : The presence of the solute uranyl nitrate does not apparently affect the miscibility of acetone with
SYSTEM URANYL NITRATE-WATERQRGANIC
SOLVENT
353
water at this temperature (25OC.). It is very obvious in this system that the solubility of uranyl nitrate is a function of the concentration of organic component. Until about 20 per cent by weight of acetone, the solubility of the uranyl nitrate increases linearly with the acetone content of the liquid phase. With lower proportions of water, the solid uranyl nitrate tetrahydrate appears, which is unknown from the uranyl nitrate-water or u m y l nitrate-nitric acid-water
HZO
FIGS.5,6. System uranyl nitrate-water-hexyl ether. A, hexahydrate and variable waterrich liquid; B, hexahydrate and two liquid phases; C, hexahydrate and variable organic-rich liquid; D, hexahydrate, trihydrate, and liquid; E, trihydrate and variable liquid; F, trihydrate, dihydrate-dietherate (?), and liquid; L, region of separation of two liquid phases; SI,S2, homogeneous liquid phases.
systems. At still lower concentrations of water, the stable solid is the trihydrate, followed by the dihydrate-monoacetonate and finally by the anhydrous diacetonate. The composition of the latter was derived in part by analogy with that for the methyl isobutyl ketone, since the anhydrous diacetonate had not been prepared pure. Uranyl nitratewatermethyl isobutyl ketone Cfigures 9 and 10; fubk 6 ) : The increase in solubility of uranyl nitrate in the organic phase when the system contains less water shows strongly. The solid phase below the hexahydrate seems
354
LEONARD I. WTZlN AND JAMES C. SULLNAN
FIG.8. See legend below figure 5 Uran
TABLE 3 nitrate-water-hew1 ether at 26OC.
OIOANZC PEASE
8
z B -
IDENTITY OF SOUD PEASE
p aCnJ
pa
9n unl per cmI
99. 60.44
0.1 0.1
0.0
43.42
0,318
3.27
UOI(NO~)Z.~H~O
1.27
13.54
UOZ(NO,)Z.~H~O
1.92 2.11 1.93
18.09 18.55 17.82
14.29 79.75 12.23 77.50 10.94 80.13
2.66
22.19 23.08
8.13 65.44 8.41 56.25
__
2.06
$6? C
d
+
UO~(NOI)Z.~HZO UOI(NO;)I*~H;O
SYSTEM URANYL NITRATE-WATER-ORGANIC
355
SOLVENT
to be the trihydrate, though there is a suggestion in the data that uncertaintiea of water analysis in the presence of the ketone may be masking the appearance of tetrahydrate. The trihydrate is followed by the dihydrate-monoketonate and finally the anhydrous diketonate. The solubility of uranyl nitrate is apparently a maximum at the point of trihydrate-dihydrate-monoketonateequilibrium, re-
.
0
IO
.
20
30
40
50
FIGS.7, 8. System uranyl nitrate-water-acetone. A , hexahydrate and variable liquid phase; DI, hexahydrate, tetrahydrate, and liquid; C, tetrahydrate and variable liquid; Dt, tetrahydrate, trihydrate, and liquid; E, trihydrate and variable liquid; F, trihydrate, dihydrate-monoacetonate, and liquid; G, dihydrate-monoacetonate and variable liquid; H, dihydrate-monoacetonate, anhydrous diacetonate, and liquid; K, diacetonate and variahle liquid; S, homogeneous solution.
ceding slightly from this value at lower water activities. The uranyl nitrate extracting into the organic phase, in the liquid-liquid equilibrium region, is accompanied by four molecules of water per uranyl nitrate, except for the highest concentrations of uranyl nitrate. Uranyl nitrate-water-isobutyl alcohol Wgures 11 and 1I; table 6): The behavior of uranyl nitrate in this solvent shows the same trend as in the others-an increase of solubility BS the water content of the system is lowered. As with the preceding, the first lower hydrate might possibly be the tetrahydrate. The evi-
FIG.8. See legend below figure 7 TABLE 4 Uranyl nitrate-water-acetone a t 26'C. LIQUID PEASE
--
I
,
SOLID PEASE
snm
PHASE
HtO
p n cent
1
per cenl
per crni
45.5 87.54 27.14 25.12 21.21 22.39 17.41 15.55 15.37
54.5
per cenl
56.77 59.99 60.75 62.06 61.37 62.71 63.29 64.46
11.73 11.71 11.33
70.34 70.45 70.30
19.36 16.06 14.45
79.20 81.53 81.33
U O ~ ( N O ~ ) ~ . ~ HUOz(NOa)z.4Hz0 IO
10.40 10.61
70.88
14.40 11.99
81.96 86.72
UOz(NOa)z~4HzO U O Z ( N O I ) Z . ~ H ~ O
70.42
9.76 9.88
70.82 70.78
11.58 8.W
86.37 80.90
7.54 8.48 9.21 9.57
71.66 69.51 68.86 69.20
6.81 6.04 4.95 5.77
80.86 78.81 78.45 75.65
UOz (NO,) z 6Hz0
+ +
356
SYSTEM URANYL NITRATE-WATER-ORGANIC
SOLVENT
357
dence is a little better than for the methyl isobutyl ketone, but not as good aa for the acetone. The next solids are the trihydrate and the dihydrate-monoalcoholate. The anhydrous solid is the trialcoholate. In the liquid-liquid distribution region, the uranyl nitrate enters the organic phase accompanied by four molecules of water.
FIQS. 9, 10. System uranyl nitrate-water-methyl isobutyl ketone. A, hexahydrate and variable water-rich liquid; B, hexahydrate and two liquids; C, hexahydrate and variable organic-rich liquid; D, hexahydrate, trihydrate, and liquid; E, trihydrate and variable liquid; F, trihydrate, dihydrate-monoketonate, and liquid; G, dihydrate-monoketonate and variable liquid; H, dihydrate-monoketonate, diketonate, and liquid; K, diketonate and variable liquid; L, region of separation of two liquid phases; Sr,SI, homogeneous solutions.
Uranyl nitratewatertertiary butyl alcohol Cfigures 19 and 14; table 7): Tertiary butyl alcohol is miscible with water, so no liquid-liquid distribution region exists in the phase diagram. The diagram is unique for the appearance of mixed-solvate solid phases which are hexasolvated. The first of these phases found is the trihydrate-trialcoholate. Because the solubility of this solid is less than that of the hexahydrate, the initial trend toward higher solubility of uranyl nitrate with increasing organic content, such aa is found with acetone, becomes reversed. The reason for the changes in curvature of the solubility plot as more alcohol is
358
LEONARD I . KATZIN AND JAMES C. SULLIVAN
added to the system is illuminated somewhat in the mole per cent plot (figure 14), aa in large part due to the maintenance of an almost constant mole fraction of uranyl nitrate in the liquid phase, with considerable difference in the molecular weights of the two solvents. There is a small contribution apparent also from the next lower solvate, the dihydrate-tetraalcoholate, which apparently tends to form a solid solution with the trihydrate-trialcoholate.The concentra-
FIG.10. See legend below figure 9
tion of uranyl nitrate in the liquid phase goea up when the tribydrate-trialcoholate has disappeared, reaching a value greater (mole per cent) than for water alone, although not as*highaa for the isobutyl alcohol and other solvents. The anhydrous uranyl nitrate in this system is again the trialcoholate. DISCUSSION
Form of uranyl nitraie in solution The increase in water concentration, in the liquid-liquid distribution region of the phase diagrams for the solvents immiscible with water, suggests that water is being brought into the organic phase in parallel with the uranyl nitrate.
EYSTEM URANYL NITRATE-WATER-ORQANIC
SOLVENT
359
TABLE 5 Uranyl nitrate-water-methyZ isobutyl ketone at S@C. O l G A N f C PBML
)nm
04.x
UI C r r l
be? CW
pa U I I
DAYP SOLID
pa C r r l
1.68
76.M 78.7( 67.M 62.3l 57.9! 57.41 66.0:
14.41 2.06 16.68 4.11 28.80 3.08 35.48 5.00 37.93 6.04 38.69 5.75 41.24 6.04
42.98
56.41 8.11 44.14 21.50 76.69
0.37 0.64 7.12 16.67 20.52 21.93 26.50
8.04 44.01 21.17 74.82 7.24 46.42 18.13 73.28 6.71 47.86 17.86 73.66 5.97 5.70 5.59 5.47 5.34
54.53 54.10 54.78 55.13 55.21
5.05 5.04 5.06 5.33 4.78 4.17
55.56 10.56 81.53 55.92 10.62 81.48 56.04 10.94 84.39 56.15 10.97 80.71 57.71 10.61 82.73 58.45 10.09 79.89
14.70 11.85 11.16 10.52 13.65
78.22 80.68 81.11 81.09 79.84
3.75 60.29 10.09 82.02 3.99 59.45 10.47 81.18 3.75 60.08 9.60 81.59 3.95 3.76 3.62 3.41
55.56 57.92 55.21 56.67
2.50 1.06 0.98 3.35
69.51 64.54 64.89 69.28
3.39 53.85 2.98 52.25 3.38 51.21 2.83 49.78
1.37 1.12 1.02 1.10
65.77 65.34 63.35 65.57
This situation may be analyzed more precisely by calculating the equilibrium compositions of the organic phase in the liquid-liquid region on a molality basis.
360
LEONARD I. KATZIN AND JAMES
c.
auLLxvu
The data and the molalities are listed in table 8. A plot of the water molality against the uranyl nitrate molality should then give the relationship, if any, between the increase in water and the increase in uranyl nitrate concentration. This has been done in figure 15. The lines connecting sets of points were oriented by eye to give good fit to the points at the lower uranyl nitrate concentrations.
FIGS. 11,12. System uranyl nitrate-water-isobutyl alcohol. A, hexahydrate and variable water-rich liquid; B, hexahydrate and two liquids; C, hexahydrate and variable organicrich liquid; D, hexahydrate, trihydrate, and liquid; E, trihydrate and variable liquid; F, trihydrate, dihydrate-monoalcoholate, and liquid; G, dihydrate-monoalcoholate and variable liquid; H, dihydrate-monoalcoholate, trialcoholate, and liquid; K, trialcoholate and variable liquid; L, region of separation of two liquids; SI,Sz, homogeneous solutions.
For only diethyl cellosolve and methyl isobutyl ketone do the highest points fail to come up to the line so drawn. It is clear from the figure that the various sets of points are well represented by straight lines. It is also striking that those for isobutyl alcohol, methyl isobutyl ketone, and diethyl ether are parallel, and that the slopes are (within experimental error) 4.0 molecules of water per uranyl nitrate, and the hexyl ether (based on two points) is 2.0 molecules of water per uranyl nitrate. The results with diethyl cellosolve correspond to expectation from the Bernal and Fowler (2) view that hexahydration in crystals represents true water CO-
SYSTEM URANYL NITRATE-WATER-ORQANIC
361
SOLVENT
ordination. In this case the uranyl nitrate transported into the organic phase a t low salt concentrations is coijrdinated with six molecules of water just aa it was in the aqueous phase. Extraction with four molecules of water must mean that two of the normal hydration complement have been stripped from the molecule. Since with isobutyl alcohol, for example, the solubility of water even in the absence of extracted uranyl nitrate is high, the effect cannot be due solely to exclusion of water from the organic solvent but must involve some positive
0
1”
$a$
90
IO
20
t,
\,
”
”~~
30
40
50
60
5, 70
80
90
310
FIG.12
action of the organic molecules. That is to say, whether uranyl nitrate appears in the organic phase with a net hydration of six or four molecules of water must depend largely on the competitive strength of the organic molecule and water with rwpect to coijrdination with the uranyl nitrate. The falling-away from the line with slope 6.0 to one with slope 4.0 means that the water activity has been lowered so that diethyl cellosolve can now replace two of the molecules of water, aa the other solvents do at higher water activities.‘ The falling-away of the 1 Note added in proof: New data obtained on other systems since thie report wm prepared (L. I. Katzin and E. Gebert: J. Am. Chem. SOC.72, 5466,5464 (1950)) indicate that the contribution of the organic component at this point is its lower dielectric constant, and that the anions. rather than two molecules of solvent, complete the coordination n u n -
362
LEONARD I. KATZIN AND JAMES C. SULLNAN
TABLE 6 Uranvl nitrale-ualer-i8obutul alcohol at &C.
-
ORGANIC P W S
-) a m # pacm
le? c a l l
88.04
I
p a cml
p6? C u l l
pa cm
82.94 77.45 74.28 61.93 56.74 62.83 49.52
6.67 12.87 16.28 30.16 33.91 38.40 43.69
15.00 14.57 0.02 14.42 0.86 13.34 1.56 14.75 10.63 14.82 16.02 14.82 24.17 14.66 30.89
39.66 39.97
65.61 65.39
16.34 46.06 16.03 46.25
21.44 21.80
77.01 75.62
12.18 9.11 6.84 6.04 6.13 5.97 6.04 5.52 6.12
46.06 46.16 49.57 49.96 51.37 51.74 64.43 55.57 57.54
19.95 19.53 21.31 19.41 19.25 18.07 19.39 18.77 18.47
75.35 73.42 76.78 75.87 73.63 74.38 74.81 75.82 76.51
4.42 4.52 4.57 4.71 4.78 4.90 4.65
57.35 57.08 57.83 57.36 57.68 57.74 57.29
10.88 10.82 13.58 11.06 11.12 13.98 9.28
82.07 81.39 81.08 79.74
3.98 3.86 4.13 4.64
58.69 58.59 58.36 58.19
8.W 7.88 11.00 9.04
80.12 79.45 84.39 81.61
UOz(NO:)r-3H:O UOz(NO:),*2H1C) C4HsOH
2.26 2.28
55.05 65.69
1.65 4.39
69.92 73.32
UOr(NOa)z~2H,O.C4HnOH UO;(NOb ;*3(i-C4HnOH)
0.53 0.75
51.07 51.20
0.79 0.73
63.65 64.26
UOI(NO~)Z.~(~-C~H~OH)
83.54
79.31 79.74
-
+
--
ber. The following discussion should be read with this modification in mind. In the case of tertiary butyl alcohol, the base strength seema such that hexasolvation is maintained, as presented in the original discussion.
SYSTEM URANYL NITRATE-WATER-ORGANIC
SOLVENT
363
methyl isobutyl ketone point represents a transition of part of the uranyl to a hydration less than four-e. g., three.2 The phenomenon falls into the wellstudied class of “electron donor and electron acceptor” or “acid-base” type of reaction. For a solvent which is a strong competitor with water, some indication might be expected in the aqueous phase of an increase in organic content with increase
n PO FIGS.13, 14. System uranyl nitrate-water-tertiary butyl alcohol. A , hexahydrate and variable liquid; D, hexahydrate, trihydrate-trialcoholate, and liquid; E, trihydrate-trialcoholate and variable liquid; F, trihydrate-trialcoholate,dihydrate-tetraalcoholate, and liquid; G , dihydrate-tetraalcoholate and variable liquid; H, dihydrate-tetraalcoholate, trialcoholate, and liquid; K , trialcoholate and variable liquid; 9, homogeneous solution.
in uranyl nitrate content, the parallel of the case with the organic phase. Complications arise both from the usual salting-out action of the increasing electro‘Presumably a t some (low) water activity level a transition t o a lower water coijrdination level (e.g., four) might occur, and if the activity of the organic component is also low, the total coordination (water plus solvent) might be only four. (It should be noted that the extraction into hexyl ether with only two molecules of water per uranyl nitrate cannot be taken as direct proof of that solvent’s competitive position with respect t o water (see below) .)
FIG 14. See legend below figure 13 TABLE 7 Uranyl nitrate-water-tertiary butyl alcohol at 85’C. LIQUID PEASE
S O D PEASE
IDENTITY OF SOLID PEASE
no pa
CmI
UOt(NO*):
JOz(NOi)r
pn
CmI
p n Crnl
p n CCd
UOz(NOa)2.6HzO
45.5 39.79
51.5 55.33
43.25 44.40 37.51 29.41 9.47 7.86 2.51
47.86 45.16 41.46 37.26 24.73 22.64 15.15
12.35 11.89 14.28 10.76 8.52 7.34 6.88
56.45 54.50 56.94 56.67 56.93 52.88 59.56
2.25 1.91
17.25 16.95 17.11
4.97 4.72 4.72
51.78 50.38 51.93
1.36
24.11
4.42
49.15
UOz(N0a)z .2HzO. 4 (CHa)rCOH
1.30
34.51
0.33
58.19
UOr(NOi)r.3(CH,)rCOH
2.06
UOz (N0a)z.3H20.3 (CHI)aCOH
364
SYSTEM URANYL NITRATE-WATER-ORQANIC
365
SOLVENT
TABLE 8 Relation between water and uranyl nitrate content oj organic phases; liquid-liquid distribution ewuilibrium owxmc
SOLVENT
per C r n l
Diethyl ether.. . . . . . , . . . . . . . . . . . . . . . , .
Diethyl cellosolve
Hexyl ether.. . . . . . . . . . . . . . . . . . . , . , . . , . Methyl isobutyl ketone... . . . . . . . . . . . . .
IBobutyl alcohol.. . . . . , . . . . . . . . . . . . . . . .
IOIWOdr
SOLVZNT
per cetll
per cmt
1.25 1.25 1.10 2.04 4.23 5.49 7.55 7.79 8.95 9.32 9.36
0.00 0.00 5.80 19.35 24.32 34.52 39.42 49.97 49.80 49.70
98.75 98.75 98.90 92.16 76.42 70.19 57.93 52.79 41.08 41.08 40.94
0.70 0.70 0.62 1.23 3.07 4.34 7.23 8.19 12.10 12.59 12,70
0.00 0.00 0.160 0.642 0.879 1.512 1.895 3.09 3.06 3.08
3.28 4.56 6.88 9.10 10.45 11.52 12.55 12.z
8.16 17.22 24.14 29.69 43 I73 53.49 54.05
96.72 87.28 75.90 66.76 59.86 44.75 33.96 33.73
1.88 2.90 5.03 7.56 9.68 14.29 20.53 20.12
0.237 0.576 0.917 1.258 2.48 4.00 4.06
