Use of Cage-Functionalized Macrocycles and Fluorinated Alcohols in

Chapter 8

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Use of Cage-Functionalized Macrocycles and Fluorinated Alcohols in the Liquid-Liquid Extraction of NaOH and Other Sodium Salts Strategies Toward Waste-Volume Reduction 1,*

1

1

Bruce A. Moyer , Peter V. Bonnesen , C. Kevin Chambliss , Tamara J . Haverlock , Alan P. Marchand , Hyun-Soon Chong , Artie S. McKim , Kasireddy Krishnudu , K. S. Ravikumar , V. Satish Kumar , and Mohamed Takhi 1

2,*

2

2

2

2

2

2

1

Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, TN 37830-6119 Department of Chemistry, University of North Texas, NT Station, Avenue C at Sycamore Street, Denton, TX 76203-5070 2

Concepts for the selective separation of sodium hydroxide and other sodium salts from alkaline high-level wastes are described together with initial results. Eight extraction mechanisms may be envisaged for transferring NaOH equivalents to an organic solvent by liquid-liquid extraction. Selectivity derives from principles of solvation, host-guest chemistry, and cation exchange. Initial results are presented on the synthesis and properties of new cage-functionalized macrocylic hosts and fluorinated alcohol cation exchangers. Such compounds show promise toward reducing the overall waste volume by removal of bulk quantities of sodium salts.

The goal of the research described in this paper is to acquire fundamental knowledge regarding the separation of sodium hydroxide and other predominant sodium salts from alkaline nuclear waste stored at various United States Department of Energy sites. The principal environmental benefit of this research is the potentially major reduction in the volume of the low-level waste stream that remains after the predominant radionuclides have been separated. The need 114

© 2001 American Chemical Society

In Nuclear Site Remediation; Eller, P., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.


115

to remove bulk constituents that would otherwise have to be vitrified in the residual low-level waste stream has recently been identified (/). Owing to the large volume of alkaline waste (55 million gallons at the Hanford site alone) and the high cost of vitrification, large cost savings could be realized. Excluding water, the composition of such waste is dominated by sodium hydroxide, nitrate, nitrite, carbonate, and aluminate salts (2). A successful technical approach to volume reduction via sodium nitrate crystallization from the waste has recently been demonstrated (3). A case for sodium hydroxide removal based on electrochemical salt splitting has also been proposed (4,5). It has been estimated that the recovery of sodium hydroxide could reduce the overall volume of low-activity waste by as much as 32% (4). Moreover, recovered sodium hydroxide could be reused for neutralization of newly generated waste, corrosion inhibition, or dissolution of alumina from sludge. Without such recycle, fresh sodium hydroxide would have to be added to the waste stream, ultimately increasing the waste volume and worsening the overall problem. It was our thought that the technological options for removal of sodium hydroxide from the waste could be further enhanced by exploiting the highthroughput potential of liquid-liquid extraction. A s befits the Environmental Management Science Program, the task of identifying optimal extractants and solvent components entails addressing some exciting forefront questions in chemical science. Perhaps the most fascinating question deals with the design of extractants that confer the needed selectivity for the simultaneous separation of a target cation, sodium, and a target anion, hydroxide. In this review, we present our multi-faceted approach to this problem, illustrating selected concepts with initial results. The following section outlines the array of extraction mechanisms that could be considered and their expected characteristics. Next we report our progress toward developing novel cage-functionalized macrocycles for the liquid-liquid extraction of various sodium salts, particularly sodium hydroxide. Finally, we report extraction results using a novel approach based on weakly acidic fluorinated alcohols. It will be seen that progress has been made toward both a practical separation process and an understanding of the fundamental chemistry of the synthesis and properties of applicable extractants.

Eight Basic Extractive Approaches to NaOH Separation Since the chemical literature offers little information on the liquid-liquid extraction of NaOH, we make at the outset no presumption as to the best practical method but rather consider here a heirarchy of applicable fundamental chemical processes. These rely on principles of solvation, acid-base reactions, and host-guest chemistry. Table I lists eight basic approaches that one might take. The first five approaches entail ion-pair extraction processes in which the


116

+

extracted cation M and anion X " may either be solvated or complexed. The receptor in each case is indicated by a circle without implying any particular topology. The last three approaches entail an acid-base reaction to transfer a hydroxide equivalent to the solvent with or without a receptor for the cation M . The cation exchanger is depicted with an alkyl tail to indicate lipophilicity. As written for all cases except 5 and 8, the product cation and anion species given in each case are dissociated in the solvent, implying ideally little or no influence of the cation and anion upon one another. However, secondary effects such as ion pairing or aggregation can be expected to influence ion selectivity. The simplest approach in concept entails choice of a water-immiscible solvent that by itself effects the extraction of NaOH from an aqueous mixture cf salts (Table I, Case 1). The solvent molecules must therefore completely accommodate the N a cation and OH" anion. For N a , this means supplying electron-pair donor (EPD) groups for coordination ((5). Likewise for OH*, hydrogen-bond donor (HBD) groups are needed (7). Since the thermochemical radii of both ions are small [ r + = 0.102 nm and r - = 0.133 nm (#)], the E P D and H B D groups must be significantly stronger than the H 0 molecules in the source phase for efficient ion partitioning. This is difficult to achieve in a water-immiscible liquid, and indeed, positive Gibbs energies of ion transfer (8) lead one to expect weak extraction. Extraction can be enhanced by use of a cation receptor (Case 2), anion receptor (Case 3), both cation and anion receptors in synergistic combination (Case 4), or a ditopic ion-pair receptor (Case 5). For present purposes, a receptor may be defined as a molecule having multiple E P D or H B D groups fix-


+

+

+

Na

0 H

2

Table I. Fundamental Approaches Applicable to NaOH Separation using Host-Guest and Liquid-Liquid Extraction Principles Case

System

Organic-phase species

1

No receptors

M+ + X -

2

Cation receptor

+

3

Anion receptor

M+ +

4

Cation receptor + Anion receptor

5

Ditopic ion-pair receptor

6

Cation exchanger

7

Cation exchanger + Cation receptor

8

Ditopic cation exchanger-receptor

x-


117

partial or complete encapsulation of guest ions. With use of any receptor, the Gibbs energy of complexation augments the Gibbs energy of ion transfer, thereby boosting overall extraction strength (9). The enhancement can also be made selective. Receptors for N a and other alkali cations are plentiful among crown ethers, cryptands, and calixarenes, for example (10). Receptors for anions are less plentiful, and OH" ion has yet to be considered (//). Naturally, strong H B D groups directed at the oxygen atom would be favorable, possibly together with an E P D group directed to interact with the hydrogen atom. Ion-pair receptors are still rare, but a few designed examples have been reported (12). As ion-pair extraction processes, Cases 1 to 5 in Table I can be adapted well to cyclic sodium hydroxide extraction and stripping. Taking Case 2 as an example, the aqueous cation ( M ) and anion (X") are transferred to a solvent phase, where the cation is then complexed with a crown ether:


+

+

+

+

N a ( a q ) + X " (aq) + Crown (org) .

[NaCrown] (org) + X " (org)

(1)

4

It may be expected from eq 1 that high Na * concentration drives extraction, and extraction may be subsequently reversed by contacting the solvent with a lowsalt aqueous solution, ideally water. Such a cycle is ideal for treatment of highsalt wastes, such as alkaline high-level tank waste, and use of water for stripping introduces no new chemicals or dissolved solids to the process (13). It is likely that a successful approach employing ion-pair extraction would require use of an anion receptor to obtain sufficient selectivity for O H " ion. When the anion is solvated as in Cases 1 and 2 in Table I, one generally observes Hofmeister-type selectivity (14). That is, extraction strength is biased in favor of larger, more charge-diffuse anions (7). Thus, the abundant anion nitrate would be preferentially extracted. In the event that anti-Hofineister behavior could be demonstrated, fluoride extraction would compete (7). Although this would be desirable in a scheme to separate nitrate or possibly fluoride salts, a bias-type selectivity would not provide O H " selectivity. A s mentioned above, a recognition approach would entail building a molecule that directs appropriate H B D and E P D groups in a geometry complementary to OH". Ironically, cation exchange provides an alternative approach for an effective extraction of OH" ion. Possessing exchangeable acidic protons, such extractants (HA) have many variants, but all function according to a common exchange process, which (neglecting complications due to aggregation and ion pairing) may be written most simply as eq 2 or its equivalent in terms of OH" (eq 3): +

N a (aq) + H A (org) • +

N a (aq) + OH" (aq) + H A (org)

+

+

H (aq) + N a (org) + A" (org) +

H 0 ( a q ) + Na (org) + A"(org) 2


(2) (3)

118

The reverse reaction affords recovery of sodium hydroxide upon stripping with water, whereby the alcohol returns to its protonated form in the organic phase. When used in tandem, the forward and reverse steps constitute a cyclic process affording the transfer of alkali metal hydroxide from an aqueous mixture into water. To function efficiently for hydroxide recovery, H A must possess weak acidity (ρΚ ca. 9-14) so that contact of the loaded solvent with water readily regenerates the protonated form of the extractant. Surprisingly, a single study involving phenols represents the only citation of such a process in the literature (15,16). A s before, a cation receptor may be added to the solvent as a synergist (17) for the cation exchanger (Case 7), and one may envision that the cation receptor could also contain the cation-exchange functionality in the same molecule (Case 8). Whereas the desired extraction-stripping cycle is again possible using water for stripping, the major advantage of any of the cationexchange approaches is the potentially high selectivity for O H " ion. Only highly basic anions can undergo the acid-base process given in eq. 3.


Λ

Synthesis of Novel, Cage-Functionalized Host Systems In relation to the problem of separating sodium salts from high-salt wastes, the structure of macrocyclic cation receptors allows control of the cation selectivity. Investigators at the University of North Texas have synthesized several cage-functionalized crown ethers and related aza-crown systems, each of which contains a 4-oxahexacyclo[5.4.1.0 ' .0 ' .0 » .0 ' ]dodecane moiety. In several instances, incorporation of this cage unit into these systems has produced a dramatic effect upon their ability to function as ionophores. Here, the cage unit functions as a lipophilic "spacer" that also serves to increase the rigidity of the crown system in the resulting macrocycle relative to the corresponding non-cage-containing analog, thereby influencing the overall conformational mobility of the host. Incorporation of the cage unit also affects the shape and size of the cavity in the host system. In addition, the furano oxygen atom in the 4-oxahexacyclo[5.4.1.0 » .0 ' .0 ' .0 ' ]dodecane cage moiety potentially can participate along with the remaining Lewis base atoms in the macrocycle during formation of an eventual host-guest complex. Our first attempts to incorporate the 4-oxahexacyclo[5.4.1.0 > .0 > . 0 » . 0 ' ] d o d e c a n e cage moiety into crown ethers resulted in the synthesis of two novel host systems, 5 and 6. The methodology that was employed successfully for this purpose is summarized in Scheme 1 (18). Thus, reaction of pentacyclo[5.4.1.0 ' .0 ' .0 » ]undecane-8,ll-dione ("PCU-8,ll-dione", 1) with excess vinylmagnesium bromide afforded the corresponding diol, 2, in 60% yield. Dehydration of diol 2 produced 3,52

6

3

2

10

5

6

3

9

8

10

5

11

9

8

11

2

5

9

8

n

2

6

3

10

5

9


6

3

10

119

Scheme 1 H C=CH-MgBr » 2


dry THF

H3B-THF dry THF

ο OTs

Ts(T\r\r^OTs

TsO

NaH, dry THF

NaH, dry THF

2

6

3

10

5

9

divinyl-4-oxahexacyclo[5.4.1.0 » .0 > .0 » ]dodecane, 3 (77% yield). Subsequent hydroboration-oxidation of the carbon-carbon double bonds in 3 afforded the corresponding cage diol, 4, in 85% yield. Diol 4 thereby prepared proved to be a key starting material for the preparation of several of the new cagefunctionalized crown ethers and cryptands reported herein. In an effort to probe the importance of proximity effects (i.e., "host preorganization") on host-guest complexation properties, a series of 3,5difunctionalized 4-oxahexacyclo[5.4.1.0 .0 ' .0 ' .0 ]dodecanes has been prepared. These compounds serve as templates to develop a series of novel complexing agents that can be used for metal ion separation and transport. Thus, for example, l-aza(12-crown-4) (i.e., l,4,7-trioxa-10-azacyclododecane) and several substituted l,4-diaza(12-crown-4) derivatives have been prepared, and these species subsequently have been affixed as pendant "arms" to the polycyclic template by using the synthetic strategy shown in Scheme 2 (19). Whereas the pendant (12-crown-4) moieties in 8, 9, and 10 are 2î6

3

10

5

9

8îll


120

Scheme 2

Ts-N TsCl

NH

W (2 equivalents)

^

/^"""*°

4 pyridine f ^ O ^ ^ i K C 0 , C H C N Downloaded by STANFORD UNIV GREEN LIBR on September 23, 2012 | http://pubs.acs.org Publication Date: November 29, 2000 | doi: 10.1021/bk-2001-0778.ch008

2

3

3

*OTs TsO'

Ts

8

Ts

H 15 > 22. +

N a

4

3

+



CO

3

Br N0 Cl-

OH-

-5.0

3.0

5.0 1 lr

1

(nm )

7.0

9.0

-5.0

-4.5

-4.0

-4.0

4

-3.5

-3.5 -

C10

-3.0

-3.0 -

-4.5

-2.5

-2.5

-1.5

-1.5 -2.0

-1.0

-1.0

-2.0 -

-0.5

-0.5

3.0

CIO/

~ Λ

1 lr

5.0

3

• •

1

7.0

OH"

(nm )

Br N0 - Cl"

y \

y F

C° °) \ CO

-5.0

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

3.0

-1.5 -

-1.0

-0.5

0.0

5.0 1 lr

1

7.0 (nm )

9.0

Figure 1. Plots of the logarithm of sodium distribution ratios vs. reciprocal thermochemical anion radiifor three aza macrocycles. Conditions: 0.05 M macrocycle in nitrobenzene, 1M aqueous sodium salt, 1:1 phase ratio, and 25 °C.

2 Q O) ο —1

0.0

0.0


127

Although this ordering seems readily defensible, it persists for none of the other anions. Thus, anion selectivity appears to depend upon the structure of the macrocycle, and the mechanism (eq 1) cannot be generalized to the other anions. Although extrapolation of the electrostatic arguments based on the radii cf bare ions would predict that extraction of NaOH and NaF by macrocycles 15, 21, and 22 would be exceedingly low, Figure 1 shows that the Z> values for these anions do not continue to follow the steeply decreasing trend. Indicated arbitrarily by a straight line segment joining the points for CI" and F", the third region of the plots in fact exhibits no obvious dependence upon ion radius. A straightforward explanation under investigation lies in the feet that the small anions are highly hydrated in organic solvents equilibrated with water. For example, the ions Br" and CI" have respectively an average of 1.8 and 3.3 water molecules per ion in water-saturated nitrobenzene at 23 °C (52). Although data are lacking, O H " and F" ions would be expected to have even greater hydration. The effect of ion hydration in the organic phase is to make the Gibbs energy of ion partitioning more favorable (7), compensating for the decreased ion radius. One could say simply that the highly hydrated anions behave as if they have effectively comparable solvation in the organic phase.


Na

The Z ) values corresponding to the anions CI", OH", and F" in Figure 1 vary depending upon the macrocycle employed. The values follow the order 21 < 15 < 22, the reverse order observed for C 1 0 " ion. Logically, the macrocycle may exert an effect on anion selectivity either i f the anion is ion paired with the macrocycle-Na complex or if the macrocycle interacts directly with the dissociated anion. The latter possibly could occur via hydrogen bonding mediated by water molecules, but there is no prior evidence in the literature by which the likelihood of this occurrence can be judged. The former possibility entailing ion pairing may occur, since ion pairing is favored by small ion radius and incomplete encapsulation of the metal cation by the macrocycle (33). N a

4

+

Cation-Exchange Approach to Sodium Hydroxide Separation Whereas the macrocyclic cation receptors presented above rely on ion-pair extraction to effect an actual transfer of both N a and O H " ions to the solvent phase, Cases 6-8 in Table I offer a powerful alternative based on a principle cf cation exchange. A pseudo sodium hydroxide extraction, Case 6, has been demonstrated (34,35) using lH,lH,9H-hexadecafluorononanol (HDFN) in 1octanol (Figure 2). This and related fluorinated alcohols are expected to exhibit requisite weak acidity and good stability. For example, the ρΚ& values of 2,2,2trifluoroethanol and 2,2,2-trifluoro-l-(4-methylphenyl)-ethanol are 12.37 (36) and 12.04 (57), respectively. 1-Octanol was chosen as the diluent so as to provide good solvation for the N a cation and putative alkoxide anion (6,7,31). The ability to extract N a O H is clearly enhanced by the addition of 0.2 M H D F N +

+



128

.6.5

I

-2.5 -1.5 -0.5

0.5

1.5

log [NaOH]

aq

.init +

Figure 2. HDFN at 0.2 M in 1-octanol extracts Na ion significantly more than the blank (1-octanol alone). Conditions: 1:1 phase ratio, 25 °C.

relative to the baseline behavior observed for the 1-octanol diluent alone. This result demonstrates a significant advantage of Case 6 over Case 1 (Table I). As expected from eq 3, NaOH could be recovered from the solvent following extraction. On contact with 7 M aqueous NaOH, the organic phase was found to contain 0.29 M Na" " ion by N a gamma tracer radiometry, somewhat higher than can be accounted for by stoichiometric deprotonation of H D F N (0.2 M ) and the background extraction by 1-octanol (0.050 M ) . On contact of the loaded H D F N organic phase with water, essentially all of the extracted N a cation was back-extracted from the 1-octanol phase within experimental error (±2%). B y titration, the aqueous OH" ion concentration upon back-extraction was shown to be equivalent to that of N a ion. The selectivity and recyclability of 0.2 M H D F N in 1-octanol were found to be excellent (34,35). Selectivity was judged under competitive conditions using a simulant (38) of a Hanford alkaline tank waste high in K (0.945 M ) , N 0 " (3.52 M ) , CI" (0.102 M ) , Al(OH) " (0.721 M ) , and fiee O H " (1.75 M ) ions. Equilibrium data were collected by N a radiometry, acid-base titrimetry, inductively coupled plasma atomic emission spectrophotometry, and ion chromatography. A convenient measure of selectivity is the separation factor ( « O H - / X - ) , defined by the ratio {[OH-] /[OH1 }/{[X-] /[X*] }. Here, this quantity indicates the relative distribution strength of O H equivalents vs. that cf other anions X " . From the analytical data, α values were found as follows: 1

2 2

+

+

+

3

4

2 2

org

aq

org

aq

-


129

α

=

35

a

β

2

5

α

=

2 8 0

0Η-/Ν0 > OH-/cl- · » ΟΗ·/Αΐ(ΟΗ) · ^ extraction was also selective for sodium, by analogy expressed as oc + + 3.5. The loaded organic phase N a concentration was 0.12 M , and contact with water resulted in near-quantitative recovery of the extracted NaOH equivalents. Four cycles of the same solvent gave identical results, demonstrating that H D F N does not significantly partition to the aqueous phase and that the solvent is recyclable. Although the selectivity data point to cation exchange via eq 3 (Case 6) as the predominant extraction mechanism, no definitive conclusion is implied at present. The question arises as to whether H D F N facilitates extraction of NaOH via cation exchange or by ion-pair extraction (Case 1), which are formally indistinguishable by mass-action behavior. That is, comparing the simplest mass-action models, a hydroxide equivalent in the organic-phase could exist as the alkoxide anion or as a solvate of hydroxide ion with a molecule of H D F N . Experiments are under way to answer this question via spectroscopy. In the meantime, the fact that the enhancement of N a extraction by H D F N takes place significantly only when the anion is OH" (34,39) suggests a process of cation exchange is taking place, since enhancement with all anions capable of receiving Η-bonds would be expected if the mechanism were solvation (7). By exploiting the strong inductive effect of fluoro- or fluorine-containing substituents in sufficiently hydrophobic alcohols, the effective reversible extraction of sodium hydroxide from waste appears feasible. We show elsewhere (34) that the efficiency of the process is consistent with the expected acidity of ionizable protons in the structures of tested extractants. 3

4

=

Na

/K


+

+

Conclusions Eight fundamental approaches have been identified for the separation cf NaOH from high-salt wastes by liquid-liquid extraction. Data show that one approach involving a putative cation-exchange process using weakly acidic alcohols appears especially promising (34,35). In fact, this study represents the first example of the use of fluorinated alcohols as cation exchangers in liquidliquid extraction. This study also demonstrates a repeatable cyclic process fir the selective recovery of hydroxide ion from aqueous salt mixtures. Investigations on such systems will continue, with a view both toward practical applications and toward understanding the underlying principles. In developing other approaches involving ion receptors, synthetic methodology has been successfully devised for the synthesis of a series of novel cage-annulated oxa- and aza-crown ethers. These crowns vary in size and type cf donor atom and accordingly vary in strength and selectivity toward alkali metal cations in picrate extraction surveys. It was possible to show that in the extraction of a series of sodium salts by three candidate macrocycles, the selectivity toward different anions also varies according to macrocycle structure.


130

It was further shown that anion radius has relatively little effect on extraction cf sodium salts of very small anions, and a rationale based on anion hydration and ion pairing was proposed.


Acknowledgments Research at Oak Ridge National Laboratory was sponsored by the Environmental Management Science Program of the Offices of Science and Environmental Management, U . S. Department of Energy, under contract number DE-AC05-96OR22464 with Oak Ridge National Laboratory, managed by Lockheed Martin Energy Research Corp. A . P. M thanks the Robert A . Welch Foundation (Grant B-963) and the Environmental Science Program of the U . S. Department of Energy (Grant DE-FG07-98ER14936) for financial support. The participation of C. K . C. was made possible by an appointment to the Oak Ridge National Laboratory Postgraduate Program administered by the Oak Ridge Associated Universities.

References 1. 2.

3. 4. 5. 6.

7.

8. 9.

Tanks Focus Area Annual Report: 1997; Report DOE/EM-0360, U . S . Department of Energy, 1997. Bunker, B . ; Virden, J.; Kuhn, B . ; Quinn, R. Nuclear Materials, Radioactive Tank Wastes. In Encyclopedia of Energy Technology and the Environment, Bisio, Α.; Boots, S., Eds.; John Wiley & Sons, Inc., New York, 1995; pp 2023-2032. Herting, D . L. "Clean Salt Disposition Options"; Report W H C - S D - W M -ES--333,Westinghouse Hanford Co., Richland, W A , 1995. Kurath, D . E . ; Brooks, K. P.; Hollenberg, G . W.; Sutija, D . P.; Landro, T.; Balagopal, S. Sep. Purif. Technol. 1997, 11, 185-198. Kurath, D . E . ; Brooks, K . P.; Jue, J.; Smith, J.; Virkar, Α. V . ; Balagopal, S.; Sutija, D . P. Sep. Sci. Technol. 1997, 32, 1-4. Moyer, Β . Α.; Sun, Y . In Ion Exchange and Solvent Extraction; Marcus, Y . , Marinsky, J. Α., Eds.; Marcel Dekker: New York, 1997; Chap. 6, pp 295-391. Moyer, Β . Α.; Bonnesen, P. V . In The Supramolecular Chemistry of Anions; Bianchi, A . Bowman-James, K . Garcia-Espana., E . , Eds.; V C H : Weinheim, 1997. Marcus, Y. Ion Properties; Marcel Dekker: New York, 1997. Cox, B . G . ; Schneider, H . Coordination and Transport Properties of Macrocyclic Compounds in Solution; Elsevier: New York, 1992.


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10. 11. 12.


13.

14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

27. 28. 29. 30.

31.

32.

Izatt, R. M.; Pawlak, K . ; Bradshaw, J. S.; Bruening, R. L . Chem. Rev. 1995, 95, 2529. The Supramolecular Chemistry of Anions; Bianchi, A . Bowman-James, Κ. Garcia-Espana., Ε., Eds.; V C H : Weinheim, 1997. Reetz, M. T., in Comprehensive Supramolecular Chemistry, F. Vögtle, Ed.; Pergamon: Oxford, 1996; V o l . 2, pp 553-562. Leonard, R. Α.; Conner, C.; Liberatore, M. W.; Bonnesen, P. V.; Moyer, Β. Α.; Presley, D . J.; Lumetta, G . J.; Sep. Sci. Technol. 34, 1043-1068 (1999). Hofmeister, F. Ach. Exptl. Pathol. Pharmakol. 1888, 24, 247. Grinstead, R. R. U.S. Patent 3,598,547, Aug. 10, 1971. Grinstead, R. R. U.S. Patent 3,598,548, Aug. 10, 1971. McDowell, W. J. Sep. Sci. Technol. 1988, 23, 1251-1268. Marchand, A. P.; Kumar, Κ. Α.; M c K i m , A . S.; Milnaric-Majerski, K.; Kragol, G . Tetrahedron. 1997, 53, 3467. Marchand, A. P.; M c K i m , A . S.; Kumar, K . A. Tetrahedron, 1998, 54, 13421. Castro, R.; Davidov, P. D.; Kumar, Κ. Α.; Marchand, A. P.; Evanseck, J . D.; Kaifer, A . E . J. Phys. Org. Chem. 1997, 10, 369. Marchand, A . P.; Chong, H.-S.; Alihodzic, S.; Watson, W . H . ; Bodige, S. G . Tetrahedron. 1999, 55, 9687. Marchand, A. P.; Chong, H.-S.; Tetrahedron. 1999, 55, 9697. Marchand, A. P.; Alihodzic, S.; M c K i m , A . S.; Kumar, Κ. Α.; Milnaric -Majerski, K.; Kragol, G . Tetrahedron Lett. 1998, 39, 1861. Marchand, A. P.; M c K i m , A. S.; Krishnudu, K. Unpublished results. Marchand, A. P.; Ravikumar, K . S. Unpublished results. Lamb, J. D . ; Izatt, R. M.; Christensen, J. J. In: Izatt, R. M.; Christensen, J. J., Eds. Progress in Macrocyclic Chemistry, Wiley-Interscience: New York, V o l . 2, 1981, pp 41-90. Wong, K. H.; N g , H. L. J. Coord. Chem., 1981, 11, 49. Ouchi, M.; Inoue, Y.; Wada, K . ; Iketani, S.; Hakushi, T.; Weber, E . J. Org. Chem. 1987, 52, 2420. Bartsch, R. Α.; Eley, M. D.; Marchand, A . P.; Shukla, R.; Kumar, K . Α.; Reddy, G . M. Tetrahedron 1996, 52, 8979. Weber, E . ; Vögtle, F. In: Vögtle, F.; Weber, Ε., Eds., Host Guest Complex Chemistry. Macrocycles. Synthesis, Structures, Applications, Springer-Verlag: New York, 1985, pp 1-41. Marcus, Y. Principles of Solubility and Solutions. In Principles and Practices of Solvent Extraction; Rydberg, J., Musikas, C., Choppin, G . , Eds.; Marcel Dekker: New York, 1992, p.24. Kenjo, T.; Ito, T. Bull. Chem. Soc. Jpn., 1968, 41, 1757-1760.


132

33.

34.


35.

36. 37. 38. 39.

Moyer, B . A. In Molecular Recognition: Receptors for Cationic Guests; Gokel, G . W., Ed.; Comprehensive Supramolecular Chemistry; Atwood, J. L . ; Davies, J. E . D . ; MacNicol, D . D . ; Vögtle, F.; Lehn, J . - M . , Eds.; Pergamon: Oxford, 1996, V o l . 1; pp 377-416. Chambliss, C. K . ; Haverlock, T. J.; Bonnesen, P. V . ; Engle, N. L.; Moyer, B . A. Environ. Sci. Technol. (In preparation). Moyer, Β . Α.; Chambliss, C . K . ; Bonnesen, P. V . ; Keever, T. J. "Solvent and Process for Recovery of Hydroxide from Aqueous Mixtures," U.S. Patent Application Ser. No. 09/404, 104, Sept. 23, 1999. Ballinger, P. J. Am. Chem. Soc. 1959, 81, 1050. Stewart, R. Can. J. Chem. 1960, 38, 399. Haverlock, T. J.; Bonnesen, P. V . ; Sachleben, R. Α.; Β . A . Moyer Radiochim. Acta. 1997, 76, 103-108. B . A . Moyer, C. K . Chambliss, P. V . Bonnesen, J. C. Bryan, A . P . Marchand, H.-S. Chong, A. S. M c K i m , K . Krishnudu, K. S. Ravikumar, V . S. Kumar, and M. Takhi, 218th Nat. Mtg. of the American Chemical Society, Aug. 22-26, 1999 (Paper No. NUCL-108).


Use of Cage-Functionalized Macrocycles and Fluorinated Alcohols in

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