Thermoregulated ion complexation effects in polymeric crown ethers 2. Polymeric sulfonamidobenzo-18-crown-6

Reactit,e Polymers, 4 (1985) 27 37

27

Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands

T H E R M O R E G U L A T E D I O N C O M P L E X A T I O N E F F E C T S IN POLYMERIC CROWN ETHERS 2. P O L Y M E R I C S U L F O N A M I D O B E N Z O - 1 8 - C R O W N - 6 * A B R A H A M W A R S H A W S K Y and NAVA K A H A N A

Department o[ Organic Chemisto', The Weizmann Institute of Science, Rehot,ot 76100 (Israel) (Received August 28. 1984; accepted in revised form January 27. 1985)

N-Dodecyl-4'-sulfonamidobenzo-18-crown-6 (DSA-CE) and polymer-bound su!fimamidobenzo-18-crown-6 were synthesized and their thermoregulated ion complexation properties in CH~OH and H,O investigated. Incorporation in the polymers of auxiliary groups, triethylammonium bromide (a permanent built-in anion) or hydroxy propylamine (a hydrogen-bonding group), slightly increased the complexation power o[ the polymers. In extraction experiments with DSA-CE from Dead Sea brine solutions, DSA-CE behaved, in the presence of picrate anions, as a potassium-selecti~,e extractant.

INTRODUCTION

The complexation of metal salts by neutral macrocyclic ligands, pointed out first by Pedersen [3], led to great interest in the synthesis of metal-coordinating compounds, particularly crown ethers. The principle that "host" cycles containing ligating atoms and consisting of "rigid ligand cavities" can efficiently complex "guest ions" of matching ionic diameter, and that the strength of the corresponding molecular complex can be tailored by adjusting the donor ligands in the macrocycles has been generally proven [4,5]. Polymeric crown ethers are a recent addition to this fast expanding field. Smid and coworkers synthesized poly(vinyl crown ethers) and studied the binding of organic and * See Refs. [1] and [2]. 0167-6989/85/$03.30

inorganic ions, and catalytic effects [6]. Blasius and his group were the first to apply polymeric crown ethers (synthesized by condensation of dibenzocrown ethers with formaldehyde, or by alkylation of chloromethyl polystyrene with benzo- or dibenzocrown) in the chromatographic analysis of alkali metal ions [7]. Insoluble styrene-divinylbenzene copolymers carrying pseudocrown groups, in which the macrocyclic structure is part of the polymer backbone, were synthesized by Warshawsky et al. [8], and by Manecke and colleagues [9]. Crown ethers separated from the main chain by a spacer such as N-nonyl-l,10-dicarboxamide were described by Molinari, Montanari, Tundo and colleagues [10,11]. Phase-transfer catalysis by polymeric crown ethers was studied extensively [9 11], and

c, 1985 Elsevier Science Publishers B.V.

28 most recently by Tomoi and colleagues [12]. Work on related macrocycles includes macrocyclic hexaketone for uranium extraction [13]. Recently, we described the synthesis of polymeric crown ethers [1,2] and diazapseudocrown ethers [2], and reported thermoregulated ion binding and release by these novel polymers. One major problem with the polymeric crown ethers described in Refs. [1] and [2] is that they contain a significant amount of phenolic hydroxyls, which are themselves weak cation-exchange groups. Development of a synthetic stategy leading exclusively to polymeric crown ethers free of any other ion exchanging groups is, therefore, very important.

RESULTS AND DISCUSSION

Synthesis of sulfonamidobenzo-18-crown-6 polymers and extractants Functional crown ethers can be prepared most conveniently from aromatic crowns such as benzo or dibenzo crown ethers by electrophilic substitution reaction on the aromatic ring. 4'-Nitrobenzo-15-crown-5, 4'-nitrobenzo-18-crown-6 and 4'-hydroxymethyl-benzo18-crown-6 were reported by Staid and coworkers [14]. 4'-Chlorosulfonyl-benzo-18crown-6 was obtained in high yield by chlorosulfonation of benzo-18-crown-6. 4'-Chlorosulfonyl-benzo-18-crown-6 reacts readily with primary amines to form hydrolysis-stable sulfonamidobenzo-18-crown-6 derivatives as shown in Scheme 1. Polymer I contains 0.7 m m o l / g of benzocrown groups and 4.9 m m o l / g of primary amine groups. Polymer I is converted by reaction with a large excess of ethylbromide to polymer I|, incorporating 0.6 m m o l / g of benzocrown groups, 0.9 m m o l / g of ammonium groups (expressed as bromide) and 3.3 m m o l / g of NH 2 groups. (The synthetic procedure of the conversion of I to lI by alkyla-

tion with ethylbromide presumably leads to secondary and tertiary amines in addition to quaternary groups. The concentration of bromide corresponds therefore, to the concentration of N + R 4 groups.) Similarly, polymer III is obtained from polymer I by reaction with 3-chloro-l-propanol. Polymer Ill carries 0.7 m m o l / g of benzocrown groups, 0.74 m m o l / g of hydroxyl groups and 4.21 m m o l / g of NH 2 groups. (Polymer III may contain N(n-propanol) groups or N,N'-di(npropanol) groups.) In addition, a hydrophobic liquid analog of polymer I, namely N-dodecyl-4'-sulfonamidobenzo-18-crown-6 (IV), was prepared for comparative purposes

[15]. The incorporation of N-dodecyl-4'-sulfonamidobenzo-18-crown-6 in a novel membrane system for electrodialysis was described previously [16]. In addition, 2,6-dinitro-4methylphenol (V) and 2,6-dinitrononylphenol (VI) were synthesized. The availability of compounds I - I V allows: (1) comparison between liquid and polymeric extractants; (2) study of thermoregulated ion complexation in polymeric crown ethers, incorporating no acidic functional groups, but incorporating basic groups (polymer I) and permanently fixed anions (polymer II), and hydrogenbonding hydroxyl groups (polymer Ill); (3) study of the role of immobilized organic counter anions (hydrophobic phenols, compounds V and VI). Thermoregulated complexation of K + salts by polymers L H and II1 The experiments were conducted in jacketed columns packed with polymers, and equilibrated by circulation of water. At the completion of the complexation step at 0°C, the eluent (CH3OH or H20 ) was passed at 50°C (or 60°C). Ion concentration was monitored in the effluent phase by atomic absorption spectroscopy. The complexation of potassium by poly-

29

XE-305 IJi-T

2

2

rty

+&(C$+,&Br

Ali SO2

(II)

3.3 mmol/g 0.6 mmol/g

NH2

0.9

Br

mmol/g

crown

C2H gBr

t

(I)

4,9 mmol/g

NY

0.7 mmol/g

crown

XE-305 n At+

iJH ko,

AH (dH2)JOH

c-l-

Ill

4.21 mmol/g

NH2

0.7

crown

mmol/g

0.74 mmol/g

Scheme

1

OH

30 TABLE 1 Complexation of K ÷ by Polymers I, II and III from 0.01 M KC1 and 0.01 M KSCN in H/O and CH3OH at 0°C Polymer

0.25 0.25 0.255

0.06 0.08 0.10

0.175 0.23 0.235

I

I

I

I

I

I

I

I

14

K + (mmol/g polymer)

KSCN K S C N KC1 KC1 (CH3OH) (H20) (CH3OH) (H20) Ia II III

18-

0 0.01 0.015

Physical incorporation of 2,6-dinitro-4-methyl phenol or 2,6-dinitro-4-nonyl phenol did not show any improvement in the complexation power of polymer I. a

6

1

o 1.2 1.0

08 0,6

~

k

0,4 !

-

I

meric crown ethers l, ll and Ill was studied in relation to solvent polarity, (CH3OH and H 2 0 ) and anion structure (CI-, hard, and SCN-, soft). The complexation of K + by polymers I, I| and IIl from 0.01 M solution of KC1 and KSCN in water and methanol at 0°C is shown in Table 1 (excellent agreement exists between the amount of K + ions bound at 0°C, and the amount released at 60°C, see experimental). Figure 1 shows the complexation (at 0°C) and release (50°C) profiles for polymer I and the salt systems mentioned above. Similarly, Figs. 2 and 3 show the same profiles for complexation (0°C) and release (60°C) for polymers II and II|. The order of complexation for the salts (solvent in parenthesis) of the three polymers is: KSCN (CH3OH) > KCl (CH3OH) > KSCN (H20) > KC1 (H20) The order of elution is inverse to the order of complexation. These results show that the complexation is dependent on the dielectric constant of the solvent and the nature of the anion. Less polar solvents and soft anions tend to increase the complexation of the cation by the crown ether, and vice-versa. Several cycles of complexation and thermal release of K + were conducted without change in the complexation power of the polymeric

-

I

40 60 80 COMPLEXATION

I

I00 0

_

I

ELUTION 20 40 60

VOLUME (ml)

Fig. 1. Complexation/elution profile of KX (X = C1, SCN) by polymer I. e: Complexation, 0.01 M KSCN/ H20/0-4°C; elution, H20/50°C; complexed/eluted (mmol), 0.06/0.06. A: Complexation, 0.01 M KC1/ CH3OH/0-4°C; elution, CH3OH/50°C; complexed/ eluted (mmol), 0.18/0.17. O: Complexation, 0.01 M KSCN/CH3OH/0°C; elution, CH3OH/50°C; complexed/eluted (mmol), 0.25/0.26.

crown ethers. Furthermore, the excellent agreement in most cases between the amount of ion complexed at low temperature and the amount released at the higher temperature indicates that the free amine groups in the polymers do not participate in the potassium binding. As shown in Fig. 2 (and in the Experimental section), these results confirm that sulfonamidobenzocrown ether polymers of type I, If, I | | , bind cations exclusively through a thermally regulated, salt complexation mechanism, unlike the previously reported polymeric crown ethers derived from polybenzylcatechol which bind cations through both salt complexation and ion exchange mechanisms [1,2]. The role of the auxiliary groups, bromide anions in polymer lI and hydroxyl groups in polymer III, can be observed from the results presented in Table 1, and discussed herein.

31 20~-

i

I

I

I

i

I

I

I

I

,

I

I

]

[

I

I

I

1

2C

18 16

1614 14-

S ~2

3 •

I0

Z

Lo O8

06 04

0 6 I / / 04

,/~ ,

20

40

60

80

t

_

I00

COMPLEXATION 0 20 VOLUME(ml)

ELUTION

40

60

80

2-0 - 2145- 60 80 I00 COMPLEXATION 0 20 VOLUME (ml)

ELUTION 40 60 80

Fig. 2. Complexation/elution profile of KX (X = C1, SCN) by polymer lI. e: Complexation, 0.05 M KC1/ H 2 0 / 0 4°C: elution, H20/60°C; complexed/eluted (mmol), 0.03/0.02. m: Complexation, 0.05 M KSCN/ H20/0-4°C: elution, H20/60°C; complexed/eluted (mmol), 0.16/0.15. A: Complexation, 0.05 M KSCN/ CH3OH/0°C: elution, CH3OH/60°C, cycle 1; complexed/eluted (mmol), 0.50/0.49. O: Complexation, 0.05 M KSCN/CH3OH/0°C; elution, CH3OH/60°C, cycle 2: complexed/eluted (retool), 0.53/0.48.

Fig. 3. Complexation/elution profile of KX (X = CI, SCN) by polymer III. O: Complexation, 0.01 M KC1/ H 2 0 / O - 4 ° C ; elution, H20/60°C; complexed/eluted (mmol) 0.025/0.034. A: Complexation, 0.01 M KSCN/ H 2 0 / 0 4°C: elution, H20/60°C: complexed/eluted (mmol) 0.21/0.20. O: Complexation, 0.01 M KC1/ CH3OH/0°C; elution, CH3OH/60°C; complexed/ eluted (mmol) 0.46/0.48. I1: Complexation, 0.01 M KSCN/CH3OH/0°C; elution, CH3OH/60°C: complexed/eluted (mmol) 0.51/0.51.

Comparison of the complexation power of the three polymers, shows that [polymer I|]K + complex is stabilized by the presence of bromide in the polymer structure, while the [polymer 111]K + complex is stabilized by hydrogen bonding with the polar hydroxyl groups. The elution curves are sharpest for polymer ! (Fig. 1) and tail off for polymers 11 and IlL indicating, as expected, a retardation of the elution process by ionic attraction to the permanent counter anion (see Fig. 2 for polymer 11) and by hydrogen bonding (in Fig. 3 for polymer 111). These findings stand in good agreement to observations on non-polymeric related crown ether systems. Pedersen himself, in his original description of the complexation of alkali ions by macrocyclic ethers

[3], has pointed out the importance of the anion to the overall complexation process, choosing picrate as a suitable lipophilic, soft anion. Phase transfer studies on crown ethers [17] have established the critical influence of the anion on the overall transfer process of the cation, concluding that the presence of a lipophilic anion (e.g., picrate) in the organic phase is essential. Asher and Marcus [18] have shown that anion solvating solvents (m-cresol or 2,4-xylenol) improved transfer of cations by dibenzo-18-crown-6 and other crowns. Recently, the readily detectable chromogenic 4'picryl-aminobenzo-crown incorporating a built-in anion was synthesized, providing a good analytical extractant for spectroscopic determination of alkali cations [19- 21].

32

Extraction of ions from brines by polymers I - I H and extractant I V The extraction of ions from a simulated solution of Dead Sea brines or from Dead Sea brine solution (d = 1.28 g / m l ) by polymeric crown ethers in columns was attempted. Crystallization in the columns and the availability of only small samples of polymers created great difficulties in the analysis of the results, as it was uncertain that the eluted salts did not stem from entrained crystals that redissolved in the elution stage. For this reason experiments with a liquid-liquid extraction system consisting of an organic phase containing extractant 1V and simulated Dead Sea brine solution were conducted. Table 2 presents the percent occupation, % O~ (relative number of occupied crown ether sites), the distribution factors, DF, and selectivity factors, S ( K + / M ) , for the system: extractant IV (0.01 M in CHC13)/simulated Dead Sea brine solution. In the presence of hard anions alone (Table 2, System A) the extractant Ndodecyl-4'-sulfonamidobenzo-18-crown-6 (abbreviated as DSA-CE), acts as a non-specific phase transfer agent, showing very low distribution factors ( D F × 1 0 3 = 0.8-4.3) and selectivities (S) for all four cations present in the simulated Dead Sea brine solution. Upon the addition of 0.01 M picrate anion (Table 2,

System B), the DF × 103 value for K + rises to 41.7, and the selectivity values increase to 37.2 ( K + / N a +) and 379 (K+/MgZ+). These results show clearly that the spherical recognition ability of the benzocrown extractant is suppressed in the absence of soft hydrophobic anion, and then restored upon the addition of such an anion. Comparison between our results and the extraction behaviour of crowns in two different systems can be made. Dibenzo-18-crown-6 extracts NaCI and KC1 from aqueous solution into anion-solvating solvents, particularly m-cresol [18]. The distribution factors are larger, 10 2 - 1 0 ° , in m-cresol, c o m p a r e d to 10 3 - 1 0 - 2 in our system, but the m-cresol concentration (in the organic phase) is threefold higher than the picrate concentration (in the aqueous phase). Comparing the new chromogenic extractants [19 21], we observe that the extraction of K + with 4'-picryl-aminobenzo-18-crown-6 is possible only from highly alkaline solutions (pH = 11.46), since the ionization of NH group is essential for the extraction process [15]. Even so, the distribution ratios, DM, for 4'-picryl-aminobenzo-18-crown-6 are only 10 - 3 t o 10 - 2 . Here D M is defined as: DM-

[ML°] + [(ML" HL)] [Ma] + [MLa] + [(ML. HC)a]

TABLE 2 Percent occupation (% Oc) of crown groups, distribution factors, DF, and selectivity constants, S, for the extraction of ions from Dead Sea brine with N-dodecyl-4'-sulfonamidobenzo-18-crown-6 (DSA-CE) in CHCI 3 M

Na + K+ Mg 2+ Ca 2 +

System B/0.01 M D S A - C E

System A/0.01 M D S A - C E

% 0k

DF ( × 103)

S(K+/M)

% 0~,

DF ( × 103)

S(K+/M)

14 2 9.7 17.1

0.83 2.0 0.65 4.3

2.4 1.0 3.3 0.50

9.5 24.5 0.8 2.9

1.12 41.7 0.11 1.42

37.2 1.0 379 29.4

S(Ca2 +/Mg 2+ ) = 6.6

S(Ca2+/Mg 2+ ) = 12.9

A: Composition of Dead Sea brine representative solution: 0.1 M KCI, 1.7 M NaCI, 1.5 M MgCI 2, 0.4 M CaC12. B: Solution A was also adjusted to 0.01 M sodium picrate. Volume ratio = l : 1, contact time = 5 min.

33 where a stands for aqueous, and o for organic. Since we have determined the total concentration of M + in the organic phase, and the concentration of ions in the high salinity aqueous phase remains unchanged, DM is practically identical to our DF. CONCLUSIONS Sulfonamidobenzo-18-crown-6 polymers i, il and !II show the same ion complexation patterns as the model (benzo-18-crown-6) or the hydrophobic analogue N-dodecyl-4'sulfonamidobenzo-18-crown-6 (IV). The ionbinding mechanism is predominantly a salt complexation process as the amine groups are "non-ligands" for alkali cations. This is reflected in the excellent agreement between the amount of ions complexed and eluted. Polymer Ii, incorporating a permanent counter anion, and polymer III, incorporating an anion solvating hydroxyl group, show therefore improved overall binding powers for salt complexation. The complete reversibility of the thermoregulated ion binding process was shown for several thermal cycles. In the extraction studies with IV it was demonstrated that efficient anion transfer is essential for the specific binding of cations by hydrophobic crown type extractants. The incorporation of hydrophobic anions (2,6-dinitro-4-nonylphenol) as an additive in the extractant system or in the polymer phase is insufficient by itself. An active anion transfer agent is necessary. This problem must be addressed and answered before crown ether extractants and crown ether polymers become effective and practical systems for alkali metal recovery and separation. EXPERIMENTAL

Chlorosulfonation of benzo-18-crown-6 In a 250 ml three-necked round-bottom flask were placed benzo-18-crown-6 [20], (11

g, 0.035 tool) in dry CHC13 (100 ml, over 4 A molecular sieves). The solution was cooled to 0 - 5 ° C and magnetically stirred. Ten-fold excess of chlorosulfonic acid (A.R., 41 g, 0.352 tool, 23.4 ml) was added within a few minutes. The temperature was allowed to rise to ambient and stirring was continued for an additional four hours, The reaction mixture was poured cautiously over ice. The separated chloroform phase was washed several times to neutrality with saturated NaC1 solution, dried over anhydrous Na2SO 4 and the solvent evaporated. The residual oil was dried under high vacuum, yielding slightly,' colored crystals, m.p. 116°C (12.4 g, 86%). Analysis: Calc. for C2~,H2)SO~CI: S, 7.809~ : CI, 8.65g~-. Found: S, 7.59g/c: CI, 9.58%. N M R ( C D C L > 8 in ppm): ABX system: 7.2 (dd, 2H, J ~ = 14 Hz, J ~ = 3 Hz), 6.85 (d, 1H, ,I I = 14 Hz), 4.4-3.4 (m, CH2CH_~O, 20H). (After the completion of this work, a report describing the synthesis of 4-chlorosulfonylbenzo-15-crown-5 appeared [22]).

A minomethylpolystyrene] ,,r,, [ N-(4'-su![onylhen:o- 18-crown-6)aminomethylpol~'stvrene/t: 4 (polymer i) A m i n o m e t h y l s t y r e n e 4% divinylbenzene copolymer (XE-305 type, 20 50 mesh beads prepared by the method described in Ref. [231:(5.0 g, 10 mmol CH~NH~ groups) and 4'-chlorosulfonyl-benzo-18-crown-6 (2.05 g, 5 mmol) dissolved in dry CHxC1 : (20 ml, over 4 A molecular sieve) were placed in an Erlenmeyer for swelling (4 hours). The solvent was removed slowly by vacuum evaporation, allowing good penetration of the chlorosulfonyl crown into the polymer. To tile residual beads there was added enough dry pyridine (A.R. over molecular sieve, 14.5 ml) to wet all the beads, yet avoid excess of liquid over the beads. The reaction mixture was allowed to stand at ambient temperature for 66 hours. CHCI 3 (50 ml) was added and the reaction mixture filtered and washed succes-

34 sively with CHC13, 10% HC1 in CH3OH, CH3OH, and then with distilled water to neutrality, and finally again with CH3OH and CHC13. The beads were dried at 50°C under vacuum to constant weight, resulting in 6.44 g of product, as sightly colored beads. Analysis: 2.14% N, 2.21% S, 3.78% C1, crown groups concentration: 0.69 mmol/g. Concentration of NH 2 groups: 4.88 mmol/g.

[A minomethylpolystyrene] ~9 [( N-triethylammoniumbromide)aminomethylpolystyrene] 19 [ N-(4'-sulfonylbenzo- 18-crown- 6)aminomethylpolystyrene] j: (polymer II) Polymer | (2.50 g) was pretreated with 1 M NaOH (30 ml) for 20 hours, then washed with H20, CH3OH, CHC13 and dried at 55°C under vacuum to constant weight (2.26 g). [Aminomethylpolystyrene]s7.6 [N-(4'-sulfonylbenzo-18-crown-6)aminomethylpolystyrene]~2.4 (2.26 g) and ethylbromide (2 ml, 27 mmol) were refluxed in CHC13 (13 ml) for 20 hours, then washed with CHC13, CH3OH, H20, saturated NaHCO 3, H20, CH3OH, and finally with CHC13. They were then dried under vacuum at 65°C to constant weight (2.663 g). Weight increase: 0.401 g. Analysis: 2.00% N, 8.79% Br. Concentration of triethylammonium bromide groups: 0.91 mmol/g; NH 2 groups: 3.276 mmol/g; crown groups: 0.584 mmol/g.

[Aminomethylpolystyrene] 50.8 N-[(3-hydroxypropyl)aminomethylpolystyrene] 357 N-4'sulfonylbenzo-18-crown-6113. 5 (polymer IIl) Polymer I (2.252 g), after treatment with 1 M NaOH as described for polymer II, was swollen in dioxane (13 ml) and refluxed with 3-chloro-l-propanol (0.5 ml, 6.5 retool) and triethylamine (0.1 ml, 0.7 mmol) for 22 hours. The usual work up yielded 2.358 g of beads. Analysis: NCHzCH2CHzOH groups: 1.74 mmol/g; crown groups: 0.66 mmol/g; NH 2 groups: 4.21 mmol/g. IR (KBr) 3450 cm -1 (NH, OH, bonded), 1000-1100 (C-O-C).

N-DodecTl-4'-sulfonamidobenzo-18-crown-6 (AD 1069) (extractant IV," DSA-CE) 4'-Chlorosulfonylbenzo- 18-crown-6 (8.616 g, 21 mmol) and n-dodecylamine (3.88 g, 21 mmol) were placed in pyridine (105 ml, dried over KOH); slight heating was noticed. After 4.5 hours at ambient temperature, the solution was poured on 10 M HC1/ice and extracted with CHC13. The organic phase was washed with dilute HC1 and with saturated NaC1 solution to neutrality, dried over Na2SO 4 and the solvent removed. The oil, 9.53 g (97%) solidified upon standing. Analysis: Calc. for C28H49NSO2: C, 60.10%; H, 8.76%; C1, 0%; N, 2.50%; S. 5.72%. Found: C, 60.27%; H, 9.40%; N, 3.08%; S, 6.14%. N M R (CDC13, ~ in ppm): 7.39-7.26 (m, A r H , 3H), 3.99-3.68 (m, 20H, O-CHzCH2-O), 3.23-3.69 (m, 2H, CH2NH); 1.57-1.38 (m, 20H, CH2), 1.24 (m, 3H, CH3).

2, 6-Dinitro-4-nonylphenol (NK-13 7) ( V) A solution of 69-70% nitric acid (1.83 ml, 0.04 mol) was added to acetic anhydride (3.7 ml) precooled to 0-5°C (solution A). Solution A was now added at 0°C-5°C during a period of 1/2 hour to 4-nonylphenol (2.217 g, 0.01 tool) in acetic anhydride (3 ml) kept at 0-5°C. After one more hour stirring at 0-5°C, the mixture was poured on ice and the two phases separated. CHC13 was added to the organic phase, which was dried over Na2SO 4 and the solvent removed, to yield 2.756 g as an oil (88.9%). Analysis: Calc. for C15Hz2N2Os: C, 58.06%; H, 7.10%; N, 9.03%. Found: C, 58.19%; H, 7.20%; N, 8.44%. Mass spectrum, M += 310 (0.96%)

2, 6-Dinitro-4-methylphenol ( VI) Solution A was prepared as described for nonylphenol. It was added to p-cresol (1.08l g, 0.01 tool) in acetic anhydride (3 ml) at

35 0 ° - 5 ° C . After one hour, the product was collected as a pale yellow solid (0.18 g). The solution was poured on HC1/ice and worked up as described above. The CHC13 solution was treated with charcoal and the solvent removed. Analysis: N M R (CDC13), 6 in ppm): 8.14 (s, 1H, OH), 7.26 (s, 2H, ArH)~ 2.45 (s, 3H, CH~).

Reaction of benzylamine and 3-chloropropanol Benzylamine (distilled, 2.18 ml, 0.02 tool) and 3-chloropropan-l-ol (Eastman, distilled, 1.68 ml, 0.02 mol) were refluxed in dioxane (8 ml) for 19 hours. The solvent was removed by distillation. The oily residue was distributed between CHC13 and 5% Na2CO 3. The organic phase was washed with 5% Na2CO 3 and with saturated NaCI solution, and then dried over NazSO 4. The solvent was removed. The residue, 3.022 g (three spots on TLC, Silica, acetone hexane 1 : 1), was separated on 120 g silica, using an e l u t i o n g r a d i e n t of acetone hexane (1 : 9 to 1 : 1), yielding 0.176 g (1.06 mmol, 53%) of N-benzyl-N-(3-hydroxypropyl)amine as a clear liquid. N M R (CDC13, 6 in ppm): 7.27 (s, 5H, ArH), 3.87 3.79 (m, 2H, CH2OH), 3.79 (2, 2H, ARCH2), 2.96-2.82 (s, 1H, OH, m, 2H, NCH2), 1.78--1.71 (m, 2H, CH2CH2CH2). The second product, 0.78 g (3.4 mmol, 17%) is N-benzyl-bis[N-(3-hydroxypropyl)amine, a white solid. The N M R spectrum (CDC13) was distinguished by two triplets at 2.95-2.81 (NH CH2) and 2.70 2.54 (CH 2 N-CH2)

Cornplexation studies on polyrners I, II and HI (Table 1) 0.01 M solutions of KC1 and KSCN in CH3OH and H20 were passed through columns of the polymers containing 1-2 g. Loading of columns by complexation was performed at 0°C, with a flow rate of 1 / 6 - 1 / 2 m l / m i n , and elution (with H20 or CH~OH)

at 50-60°C, at 1 / 6 - 1 / 2 m l / m i n , Solutions were analyzed by atomic absorption spectroscopy (Varian A-1000). The following sequence of operations was carried out on polymer samples in a 1.1 × 9.0 cm column equipped with an outer jacket for water circulation. (V (CH3OH) = 5.5 6.0 ml).

Polymer I (AD-1067): Conditions See polymer 1I, cycles 1, 3 and 6. Polymer I." Complexation results Cycle 1. Complexed: 0.250 m m o l / g K S C N / CH3OH, 0°C; eluted: 0.20 m m o l / g (CH3OH, 50°C). Cycle 2. Complexed: 0.06 m m o l / g K S C N / H20, 0°C; eluted: 0.06 m m o l / g (H20, 50°C). Cycle 3.Complexed: 0.18 m m o l / g K C I / CH3OH: eluted; 0.17 m m o l / g (CH3OH, 50°C).

Polymer II (NK 141)." Conditions Cycle 1. (1) methanol wash: (2) complexation from 0.01 M K S C N / C H ~ O H at 0°C; ( 3 ) t h e r m a l elution with CH3OH at 60°C. Cycle 2. (1) 0.01 M KSCN (CH3OH, 0°C); (2) elution with CH~OH at 60°C. Cycle 3. (1) Water wash: (2) complexation from0.01 M K S C N / H 2 O a t 0 4°C: (3) thermal elution with H20 at 60°C. Cycle 4.(1) complexation from 0.01 M K C 1 / H : O at 0-4°C: ( 2 ) t h e r m a l elution with H . O at 60°C. Cycle5. (1)0.05 M K S C N / H ~ O at 20°C for exchange of CI to SCN : (2) thermal elution with HA) at 60°C. Cycle 6. (1) methanol wash: (2) complexation from 0.01 M K C I / C H 3 O H at 0°C; (3) thermal elution with CH3OH at 60°C. Cycles 7 and 8 as for cycle 6.

36

Polymer H: Complexation results

Cycle 1. Complexed: 0.250 mmol/g KSCN (CH3OH, 0°C); eluted: 0.245 mmol/g (CH3OH, 60°C). Cycle 2. Complexed: 0.265 mmol/g KSCN (CH3OH, 0°C); eluted: 0.24 mmol/g (CH3OH, 60°C). Cycle 3. Complexed: 0.08 mmol/g KSCN (H20, 4°C); eluted: 0.075 mmol/g (H20, 60°C). Cycle 4. Complexed: 0.015 mmol/g KC1 ( H 2 0 , 4°C); eluted: 0.01 mmol/g (H20, 60°C). Cycle5. Complexed: 0.09 mmol/g KSCN (H20 , 4°C); eluted: 0.08 mmol/g (H20, 60°C). Cycle 6. Complexed: 0.205 mmol/g KC1 (CH3OH, 0°C); eluted: 0.25 mmol/g (CH3OH, 60°C). Cycle 7. Complexed: 0.235 mmol/g KC1 (CH3OH, 0°C); eluted: 0.25 mmol/g (CH3OH, 60°C). Cycle 8. Complexed: 0.23 mmol/g KC1 (CH3OH, 0°C); eluted: 0.235 mmol/g (CH3OH, 60°C). Cycles 7 and 8 were performed to recheck discrepancy in cycle 6. Polymer 11I (NK-157): Conditions

Cycle 1. (1) methanol wash; (2) 0.01 M KSCN, CH3OH, 0°C; (3) CH3OH, 60°C. Cycle 2. (1) 0.01 M KC1, CH3OH, 0°C; (2) CH3OH, 60°C. Cycle 3. (1) H20 wash; (2) 0.01 M KSCN, H20, 4°C; (3) H20, 60°C. Cycle 4. (1) 0.01 M KC1, H20, 0-4°C; (2) H20, 50°C. Polymer lIl: Complexation results

Cycle 1. Complexed: 0.255 mmol/g KSCN/ CH3OH; eluted: 0.255 mmol/g. Cycle 2. Complexed: 0.23 mmol/g KC1/ CH3OH; eluted: 0.24 mmol/g, CH3OH.

Cycle 3. Complexed: 0.105 mmol/g KSCN/ CH3OH, 0-4°C; eluted: 0.105 m m o l / g , H20.

Cycle 4. Complexed: 0.0125 mmol/g KC1 (H20, 0 - 4 ° C ) ; eluted: 0.017 mmol/g, 50°C, H 2 0 . Liquid-liquid extraction studies (Table 2)

The following solutions were prepared: (A)

0.01 MN-dodecyl-4'-sulfonamidobenzo-18-crown-6 in CHC13

(B)

0.01 M N-dodecyl-4'-sulfonamido-' benzo-18-crown-6 , in CHC13 0.01 M 2,6-dinitro-4-nonyl phenol

(C)

0.01 M N-dodecyl-4-sulfonamidobenzo-18-crown-6 / in CHC13 0.01 M 2,6-dinitro-4-methyl phenol

The extractants, solutions (A)-(C), and the tested solutions, including brine solutions from the Dead Sea, Israel (F~, specific gravity 1.280 g/ml) were equilibrated in equal volumes in a "vortex" test tube vibrator for 5 minutes. The phases were separated and the organic phase was filtered through a Whatman phase-separating filter paper (P.S.) to remove any entrained water and salts. The organic phase was now twice back extracted with 0.1 M HC1. The HC1 extracts were combined and analyzed for Na +, K +, Mg 2+, Ca 2+ by atomic absorption spectroscopy. The analysis of the Dead Sea brine (1::1) solution is (g/l): Ca--16.4, Mg--36.1, Na--38.5, K--6.8, C1--157, Br--4.6, SO4--0.6 , HCO3--0.2, which corresponds to 30 g/1 KC1, 40 g/1 NaC1 and 300 g/1 MgC12. A representative solution was made for this study, with the following composition KC1--0.1 M, NaCI--I.7 M, MgC12--1.5 M, CAC12--0.4 M. Extraction of Na + and K + from simulated Dead Sea solution, with I V (O.07 M in CHC13) and 2,6-dinitro-4-nonvl- or 2,6-dinitro-4-methylphenol

A solution of N-dodecyl-4'-sulfonamidobenzo-18-crown-6 (IV, DSA-CE) and (0.01

37

M) 2,6-dinitro-4-nonylphenol (0.01 M) in CHCI~ (A) was contacted for 5 minutes with simulated Dead Sea solution. Similarly IV and 2,6-dinitro-4-methylphenol (both 0.01 M) in CHCI~ (B) were contacted with same solution. Percent occupation of crown groups (% O<) is 2.0% K + and 10.9% Na + for A; and for B: 2.2% K + and 13.1% Na +.

ACKNOWLEDGEMENT We wish to thank Israel Chemicals (ICL), Ltd., for a grant to support this work. This work is summarised in a report to ICL, dated November 1981. REFERENCES 1 A. Warshawsky and N. Kahana, Temperature-regulated release of alkali metal salts from novel polymeric crown ether complexes, J. Amer. Chem. Sot., 104 (1982) 2663. 2 N. Kahana, A. Deshe and A. Warshawsky, Synthesis of polymeric crown ethers and thermoregulated ion complexation effects, J. Polym. Sci., Polym. Chem. Ed.. 23(1) (1985) 231. 3 C.J. Pedersen, Cyclic polyethers and their complexes with metal salts, J. Amer. Chem. Soc., 89 (1967) 7017. 4 R.M. Izatt, D.J. Eatough and J.J. Christensen, Cation macrocyclic crown interaction, in: D.J. Dunitz (Ed.), Structure and Bonding, Vol. 16, Springer Verlag, Berlin, 1973, p. 161. 5 R.M. Izatt and J.J. Christensen (Eds.), Progress in Macrocvclic Chemistry, Wiley-lnterscience, New York, 1979. 6 ,1. Smid. S.C. Shah, R. Sinta, A.J. Varma and L. Wong, Macrocyclic ligands on polymers, Pure Appl. Chem., 51 (1979) 111. 7 E. Bhlsius. W. Adrian, K.P. Janzen and G. Klaute, Darstellung und Eigenschaften yon Austauschern auf Basis yon Kronenverbindungen, J. Chromatogr., 96 (1074) 89. 8 A. Warshawky, R, Kalir, H. Bercovitz and A. Patchornik. Polymeric pseudocrown ethers. I. Synthesis and complexation with transition metal anion,,, J. Amer. Chem. Soc., 101 (1979) 4249. 9 K. Hiratani, P. Reuter and G. Manecke, Preparation and catalytic behaviour of pendant otigoethyleneoxy groups (polymers of non-cyclic crown ethers), Irs. J. Chem., (197% 208.

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