Synthesis of fluorinated phosphonic, sulfonic, and ...

Synthesis of fluorinated phosphonic, sulfonic, and mixed phosphonic/sulfonic acids DEBAOSU, WENBIAOCEN,ROBERTL. KIRCHMEIER, AND JEAN'NEM. SHREEVE~ Department of Chemistry, University of Idaho, Moscow, ID 83843, U.S.A . Received February 3, 1989

Can. J. Chem. Downloaded from www.nrcresearchpress.com by Renmin University of China on 06/03/13 For personal use only.

This article is dedicated to Professor Ronald J . Gillespie on the occasion of his 65th birthday

DEBAO SU, WENBIAO CEN,ROBERT L. KIRCHMEIER, and JEAN'NE M. SHREEVE. Can. J. Chem. 67, 1795 (1989). H(CF2)20(CF2)2P(0)(OH)2, H(CF2)20(CF2)4P(0)The acids (H0)2P(0)CFHS03H, (H0)2P(0)(CF2)40(CF2)2S03H, (OH)2, (H0)2P(0)(CF2)20(CF2)4H, and the acid precursor (C2H50)2P(0)CF(S03Na)2have been synthesized. Elemental analysis, 1 9 ~'H, , and 3 ' NMR, ~ and mass spectroscopy were used for characterization of these materials. They are very strong acids, and exhibit a high degree of stability in aqueous solution at elevated temperature, which makes them attractive candidates for use as electrolytes in fuel cells. Key words: fluorinated phosphonic acids; fluorinated sulfonic acids; 'H, 1 9 ~31P , NMR.

DEBAO SU, WENBIAO CEN,ROBERT L. KIRCHMEIER et JEAN'NE M. SHREEVE. Can. J. Chem. 67, 1795 (1989). H(CF2)20(CF2)2P(0)(OH)2,H(CF2)20On a synthCtisC les acides (H0)2P(0)CFHS03H,(HO)2P(0)(CF2)40(CF2)2S03H, (CF2)4P(0)(OH)2, (H0)2P(0)(CF2)20(CF2)4Hainsi que de leur prtcurseur acide (C2H50)2P(0)CF(S03Na)2.Pour la caract6risation de ces composCs, on a fait appel i l'analyse ClCmentaire, B la RMN du 1 9 ~du , 'H et du 3'P ainsi qu'8 la spectromCtrie de masse. Ces composCs sont des acides trks forts et ils sont trks stables en solution aqueuse, B tempirature Clevte; ces caracttristiques en font d'excellents candidats cornrne Clectrolytes dans des cellules B combustible. Mots cle's : acides phosphoniques fluorCs; acides sulfoniques fluorks; RMN du 'H, du ' 9 et ~ du 3'P. [Traduit par la revue]

Introduction Many fluorinated sulfonic and phosphonic acids exhibit properties that make them potentially useful as electrolytes in fuel cells. They are much stronger acids than their nonfluorinated analogues, and are generally more stable. In addition, oxygen solubility is greatly enhanced, and volatility at elevated temperatures may be lower. In fuel cell applications, these factors combine to provide increased conductivity, enhanced oxygen reduction kinetics, and longer term system stability when compared to phosphoric acid as the electrolyte. The primary acid used in fuel cells today is H3PO4. However, it has many drawbacks, including low oxygen solubility and anion adsorption on the catalyst surface. There is a need to develop new compounds that have the desirable properties of H3PO4but fewer of the less desirable ones, in order to enhance the usefulness of fuel cells as alternative energy sources. Fluorocarbon electrolytes have the ability to lower the surface tension of water. This effect is in part due to several structural factors: (1) terminal grouping; (2) chain-length; and (3) the presence of heteroatoms in the chain. For example, a CF3 terminal group attached to a CF2 chain will have a greater surface tension lowering effect than a HCF2 terminal group attached to a similar chain. The solubility of oxygen in fluorocarbon systems is dependent on the boiling point, density, molecular weight, and viscosity of the fluorocarbon. These properties in turn are dependent in part on the structural factors and composition mentioned above. At low temperature trifluoromethanesulfonic acid has been found to be superior to H3P04 with respect to electrode kinetics. However, the acid hydrate is too volatile for extended use at the operating temperature of fuel cells (>100°C), and in addition it tends to wet the Teflon surface of the electrodes used (1). A variety of other partially fluorinated or perfluoroalkylsulfonic and disulfonic acids (1-5) as well as phosphonic acids ( 6 4 , mixed sulfonic or phosphonic/carboxylic acids (9), and a mixed sulfonic/phosphonic acid (10) have been synthesized for evaluation as potential fuel cell electrolytes. ' ~ u t h o to r whom correspondence may be addressed.

To further the evaluation of structure and composition factors effective for fuel cell electrolytes, we have prepared a number of additional partially fluorinated and perfluoro mixed sulfonic/ phosphonic, and phosphonic acids. Electrochemical testing of these acids in model fuel cells should provide valuable information in this regard.

Results and discussion The starting material for the preparation of the mixed acid (H0)2P(0)(CF2)40(CF2)2SOsH is the iodide I(CF2)40(CF2)2S02F, which was prepared by the literature method (1 1). I(CF2)40(CF2)2S02F+ (C2H50)2POP(OC2H5)2

HCl

(C2H5O)2P(O)(CF2)4O(CF2)2so3Na 2 (93%)

(HO)2P(0)(CF2)4O(CF2)2SO3Na

acid resin

3 (88%)

(HO)2P(0)(CF2)40(CF2)2S0,H 4 (76%)

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Removal of inorganic impurities from 1 was found to be necessary for the successful synthesis of 2 , 3 , and 4. Compound 3 is converted to 4 by passing an aqueous solution of 3 through a 20 mrn x 30 cm long column packed with Amberlite IR-120 resin at an approximate flow rate of 2 mL/min. Purification was accomplished by repetitive dissolution of 1 in acetonitrile, followed by filtration. Attempts to simplify the synthesis of 4 by replacing the starting material I(CF2)40(CF2)2S02Fwith I(CF2)40(CF2)2S02C1or I(CF2)40(CF2)2S03Nawere unsuccessful. The sulfonyl chloride reacted vigorously with tetraethylpyrophosphite in the absence of di-tert-butylperoxide to give a complex mixture. No suitable solvent for the reaction 'of the sodium sulfonate with tetraethylpyrophosphite could be found. Conversion of I(CF:!)40(CF2)2S02F or I(CF;,)20(CF2)2S02F to the respective diiodide

I(CF2),0(CF2 ),SO2F

K2S03 H20/CH3CN, 25"C,8 h

, r

800C'7h

+

CFBr3

12 + Na2S204

13

+

0

H202

n =2

(80%) = 4 (71%)

I(CF2)nO(CF2)21 5(n=2)and6(n=4) (39%) (37%)

provided the starting materials for the synthesis of H(CF2)20(CF2)4P(O)(OH)2, (H0)2P(0)(CF2)20(CF2)4H7 and H(CF2)2O(CF2)2P(O)(0H)z.

O°C

4h

b (C2H50)2P(0)CFBr2

--c

13 (64%)

25°C

5h 14 + Zn b

(C2H50)2P(0)CFBrS03Na

14 (75%)

(1) 60°C, 6 h, THF

(2) H20

12 (77%)

((C2H50)2 P(0)CFBrS02Na

25 "C, 4h

15 + HC1 I(CF2),0(CF2 )2S02K 11

I2 CH3CN

(C2H50)3P

(C2H50)2P(0)CFHS03Na 15 (49%)

(HO),P(0)CFHS03 Na

16 (59%) Compound 16 was then converted to the final acid product utilizing Amberlite IR-120 acid resin. 16

acid resin

'

(H0)2P(0)CFHS03H 17 (80%)

Alternatively, treatment of 14 with sodium dithionite results in the formation of the disodium salt 18. 14

Na2S204

NaHC03 0°C,4 h

b

(C2H50)2P(0)CF(S03Na)(S02 Na) 18 (80%)

The corresponding di(sodium sulfonate) is then obtained by oxidation with hydrogen peroxide.

(CH3)3COOH b H(CF2)2O(CF2)2P(O)(OC2H5)2 MeOH

However, the product of the tetraethylpyrophosphite reaction with 6 is a mixture of H(CF2)40(CF2)2P(OC2Hs)2and (C2Hs0)2P(CF2)40(CF2)2H. This intermediate mixture was separated by distillation under reduced pressure prior to conversion to the corresponding acids H(CF2)40(CF2)2P(0)(OH)2 10 and (H0)2P(0)(CF2)40(CF2)2H 11. NO evidence for the formation of any other products, i.e., ether-containing diphosphonic acids, was obtained. (Sulfomonofluoromethyl)phosphonic acid, (HO),P(O)CFHS03H, was prepared as described below from triethylphosphite and tribromofluoromethane.

It was not possible to convert this salt to the acid by using HCl,, . Other methods for conversion to this interesting disulfonicl phosphonic acid are under study. Titration of aqueous solutions of either 17 or 4 with sodium hydroxide (0.0508 N) gave rise to two inflection points, one for 2 equivalents (the sulfonic acid proton and one phosphonic acid proton) and one for 1 equivalent (the second phosphonic acid proton) of the acid. The total titre for 17 gives 97% of a tribasic acid based on an anhydrous molecular weight of 194 g/mol. For 4 the total titre gives 100% of a tribasic acid based on an anhydrous molecular weight of 478 glmol. When 4 is dissolved in isopropyl alcohol and titrated with a toluene/methanol solution of tetrabutylammonium hydroxide (TBAH, 0.0392 N), two equivalence points are observed at approximately equal volumes of titrant. Addition of a slight excess (- 10%) of TBAH after the second inflection point was followed by the addition of 10 mL (- 15%) of H20. When the electrode had stabilized, the titration with TBAH was continued to a third inflection point. The three acid protons are easily resolved by this combination of nonaqueous/aqueous titration. In summary, successful routes to a variety of mixed phosphonic/sulfonic acids, and partially fluorinated phosphonic acids have been developed. Study of several of these acids in

1797

SU ET AL.

fuel cell systems should provide valuable insights regarding the effects of particular structural moieties on the performance of fluorinated electrolytes.

Experimental


Materials The literature method was used to prepare I(CF2)40(CF2)2S02F (1 I). Other chemicals were obtained as follows: Na2S204,CH3CN, and HCl (Merck); NaHC03, H202(30%), and K2SO3(J. T. Baker); charcoal (activated "Norit" SGII) (MCB). General procedures The ' 9 NMR ~ spectra were obtained on a JEOL FX-90Q Fourier transform NMR spectrometer operating at 84.26 MHz. Chloroform-d, D20, CD3CN, or DMSO-d6 was used as solvent with CFC13 as ~ spectra were obtained at an operating external reference. 3 1 NMR frequency of 36.20 MHz with H3PO4 as an external reference. 'H NMR spectra were recorded at 89.56 MHz. Mass spectra were recorded with a VG 7070HS mass spectrometer with FAB at 3.9, 4.8, or 10 V. Elemental analyses were performed by Beller Mikroanalytisches Laboratorium, Gottingen, Federal Republic of Germany.

Preparation of (HO)2P(0)(CF2)40(CF2)2S03Na, 3 A mixture of 4.3 g of (C2H50)2P(0)(CF2)40(CF2)2S03Na (7.7 mmol) and 4.5 g of hydrochloric acid (12 N) were stirred vigorously at 120°C for 6 hand the reaction mixture was filtered. The filtrate was evaporated to dryness under vacuum to give 3.4 g (6.8 mmol) of 3 in 88% yield. Spectral data are ' 9 ~NMR, cf,: -83.28m CF2, -84.09m CF2, -118.85s CF2, -121.51m CF2, -124.12d CF2 (Jp-F = 79.18 Hz), -126.14m CF2; 3 1 ~6: -3.27. ~ ~ ~ ,

4 Preparation of (HO)2P(0)(CF2)40(CF2)2S03H, An aqueous solution of 2.3 g of (HO)2P(0)(CF2)40(CF2)2S03Na (4.6 mmol) was passed through an Amberlite IR-120 ion exchange resin at an approximate flow rate of 2 mL/min. The resulting solution was evaporated to dryness under reduced pressure. The crude product was dissolved in water and 0.15 g charcoal was added. The mixture was stirred at room temperature for 2 h. After the charcoal was removed by filtration, the filtrate was evaporated at reduced pressure at a temperature of 100°C to give 1.7 g 4 (3.5 mmol, 76% yield). The acid is a white solid, mp 91-92"C, and is very hygroscopic. Spectral data ~ 0 : -81.89m CF2, -82.99m CF2, -118.03s CF2, are 1 9 NMR, - 120.70mCF2,- 123.16dt CF2 ( J P - = ~ 79.18 Hz, J F -=~14.01 Hz), - 125.16t CF*; 3 ' NMR, ~ 6: -3.76t; 'H NMR, 6: 9.62s; MS (CI, mle (species) %):-479 (M+ + 1) 16, 281 ( ( H O ) ~ P ( O ) C F ~ C F ~ C F ~ C F ~ + ) 16, 231 ((H0)2P(O)CF2CF2CF2+) 11, 181 ((H0)2P(O)CF2CF2+) 8, 131 ((H0)2P(O)CF2+)38, 111 (HOjPCF+) 11, 100 (C2F4+) 68, 81 ( ( H 0 ) 2 P ( 0 ) + )46, 65 ((H0)2P+) 100. Anal. calcd. for C6H3FI2o7PS.H20: C 14.52, H 1.02, F 46.0, P 6.24, S 6.46; found: C 14.79, H 1.02, F45.4, P 6.25, S 6.37.

Preparation of (C2H50)2P(0)(CF2)40(CF2)2S02F A mixture of I(CF2)40(CF2)2S02F(20.3 g, 38 mmol) and tetraethyl pyrophosphite (9.55 g, 57 mmol) in CF2C1CFC12 (83 mL) with di-tert-butylperoxide (2.8 g, 19 mmol) was heated at 120°C for 3 h in a 150-mL autoclave. After reaction the mixture was placed in a glass flask fitted with a dropping funnel. The flask was cooled to -10°C under nitrogen and a solution of tert-butylhydroperoxide (138 mmol) K Preparation of l(CF2)40(CF2)2S02 in methanol (46 mL) was added slowly via the dropping funnel. After In a 250-mL three-necked round-bottomed flask were placed 15 g addition was complete at - 10 to -5OC, stining was continued at 0°C (28.5 mmol), 13.6 g of K2SO3(86 mmol), of I(CF2)40(CF2)2S02F for 1 h. 60 mL water, and 40 mL CH3CN. Under a stream of nitrogen the The solution was washed with water (50 mL X 3) and volatile contents were stirred vigorously at room temperature for 10 h. The materials were removed in vacuo. The residue was distilled under reaction mixture was filtered and the filtrate was evaporated to dryness reduced pressure to give 9.83 g of (C2H50)2P(0)(CF2)40(CF2)2S02Funder reduced pressure to give a white residue. Inorganic impurities (yield 48%); bp 133"C/l. 1 Torr (1 Torr = 133.3 Pa). Spectral data were removed by repetitive extraction with CH3CN. Finally, the solid ~ 0 : 44.48m S02F, -82.99m CF2, -83.92m CF2, are ' 9 NMR, was dried under vacuum at 70°C for 4 h to give 11.1 g (71% yield) of -113.05m CF2, -121.80m CF2, -123.45dt CF2 ( J P - ~= 83.58Hz, I(CF2)40(CF2)2S02K(20.3 mmol). Spectral data are ' 9 NMR, ~ cf,: J F - F = 14.6 HZ), -126.08t CF2; 3 ' NMR, ~ 6: -1.58t; I H NMR, 6: -64.29m CF2, -83.24m CF2, -83.86m CF2, -114.44m CF2, 1.19t CH3 ( J H - = ~ 6.96 Hz), 4.18m CH2;MS (CI, m/e (species) %): -125.22m CF2, -134.36s CF2. 537 (M+ + 1) 64,509 (M+ + 1 - C2H4)40,495 (M+ + 1 - C3H6)36, Preparation of l(CF2)40(CF2)21,6 481 (M+ + 1 - C4Hs) 83, 397 ((CF2)2O(CF2)4(O)(OH)2P') 25, 137 Under a stream of nitrogen, a mixture of 11.1 g I(CF2)40(CF2)2((C2HsO)2(O)P') 60,109 (CzH,o(o) (OH)P+) 100,81 ((H0)2(O)P+) S02K (20.3 rnmol), 6.8 g I2 (26.8 mmol), and 30 mL of CH3CN was 46. Anal. calcd. for C10H10F1306PS: C 22.40, H 1.88, F 46.06, stirred vigorously at 80°C for 7 h. A saturated NaHS03 aqueous P5.78, S 5.98; found: C 22.38, H 1.71, F46.4, P 5.88, S 6.03. solution was added to the reaction mixture to remove excess I2 at room Preparation of (C2HsO)rP(0) (CF2)40(CF2)2S02Na,1 temperature. The mixture was filtered and the filtrate was dissolved in In a 50-mL three-necked round-bottomed flask were placed 9.3 mmol 50 mL of ether. The ether solution was washed with water repeatedly. (C2H50)2P(0)(CF2)40(CF2)2S02F, 18.6 mmol Na2S204,18.6 mmol After drying, 4.3 g of colorless liquid 6 (7.5 mmol) was obtained and NaHC03, 8 mL H20, and 4 mL of CH3CN. Under a stream of purified b distillation (bp 60°C/10 Torr). The yield is 37%. Spectral nitrogen, the contents were stirred vigorously at 85OC for 2 h. After data are FNMR, 0 : -64.64m CF2, -70.13s CF2, -84.61m CF2, cooling, the reaction mixture was filtered. The filtrate was evaporated -86.64m CFz, -114.50m CF2, -125.33m CF2. to dryness under reduced pressure to give a white solid that was purified Preparation O ~ H ( C F ~ ) ~ O ( C F ~(OC2H5)2 )~P(O) u ~ ~ H ( C F ~ ) ~ O ( C F ~ ) ~ by repetitiveextraction withCH3CN. Finally 4.5 g (8.3 mmo1)of 1was P(O) ( O C ~ H S ) ~ 9 ~ cf,: -82.53m ~ ~ CF2, ~ , obtained in 90% yield. Spectral data are 1 A mixture of 4.3 g of I(CF2)40(CF2)21(7.5 mmol) and 5.8 g of -82.99m CF,, - 120.70m CF2, - 121.57dt CF2 ( J P - ~= 74.78 Hz, tetraethylpyrophosphite (22.5 mmol) in 20 mL of CF2C1CFC12with JF-~ = 14.01 HZ), -125.22t CF2, -133.26s CF2; 3 1 NMR, ~ 6: 1.1 g of di-tert-butylperoxide (7.5 mmol) was heated at 120°Cfor 3 h in -4.73t; 'H NMR, 6: -1.13t CH3 ( J H - = ~ 6.97 Hz), 3.87m CH2. a 75-mL autoclave. After reaction, the mixture was placed into a glass Preparation of (C2H50)2P(0)(CF2)40(CF2)2S03Na, 2 flask fitted with a dropping funnel. The flask was cooled to -lO°C Into a 30-mL flask were placed 8.3 mmol of (C2H50)2P(0)(CF2)4- under a nitrogen atmosphere and a solution of tert-butylhydroperoxide 0(CF2)2S02Naand 5 mL of water. At O°C, a 3:l mole ratio of (60 mmol) in 20 mL of methanol was slowly added via the dropping hydrogen peroxide (30%) was added dropwise. The mixture was then funnel. After complete addition at - 10 to -S°C, stirring was continued stirred at room temperature for 12 h. After reaction, solvent was at 0°C for 1 h. The solution was washed with water (15 mL x 3) and removed under reduced pressure, and the residue was dried to give volatile materials were removed in vacuo. The residue was distilled ~ cf,: -82.06m CF2, 4.3 g of 2 (93% yield). Spectral data are 1 9NMR, under reduced pressure to give 0.75 g of H(CF2)40(CF2)2P(0)-83.17m CF2, -118.03s CF2, -120.81m CF2, -121.83dt CF2 (OC2H5)2(1.65 mmol) and 0.25 g of H(CF2)20(CF2)4P(0)(OC2H5)2 ( J p - ~= 73.24 HZ, J F - = ~ 14.6 HZ), -125.16t CF?; 31PNMR, 6: (0.55 mmol). The combined yield is 29%. Spectral data for HCF2- 4 . 6 1 ~'HNMR, 6: 1 . 1 3 CH3 ( J H - = ~ 7.33Hz), 3.93mCH2. CF2CF2CF20CF2CF2P(0)(OC2H5)2 (bp 97"C/0.5 Torr) are 1 9 NMR, ~

'B

1798


I

CAN. J. CHEM. \IOL. 67, 1989

Preparation of (C2H50)2P(0)CFBrS02Na, I3 , In a 50-rnL three-necked round-bottomed flask were placed 10.04 g (57.6 mmol) of Na2S204,4.84 g (57.6 mrnol) of NaHC03, and 16 g (48 mmol) of (C2H50)2P(0)CFBr2.Ten millilitres of water and 10 mL of CH3CN were added. Under a stream of nitrogen, the contents were stirred vigorously at room temperature for 4 h. The reaction mixture was evaporated to dryness under reduced pressure to give a white product that was extracted with acetonitrile. The extract was filtered to remove solids, and the filtrate was evaporated to dryness under reduced pressure to give 13.8 g (84.4% yield) of 13. Spectral dataare "F NMR, Preparation of H(CF2)20(CF2)2P ( 0 )(OC2H5)2,7 @: -136.36d(JF-P = 83.01 HZ);~'P{H}NMR, 6:9.76d; 'HNMR, 6: The method of preparation is the same as that described for ~ 6.96 HZ), 4.37q (lH), 4.46q (1H) (JH-p = HCF2CF2CF2CFzOCFzCFzP(0)(OC2H5)2 and HCF2CF20CF2CF2- 1.43t (3H, J H - = 8.03 Hz); MS (FB', solv. H20, m / e (species) %): 354 (M'" + H20) CF2CF2P(0)(OC2H5)2 above. The overall yield is 16%. Spectral data 0.7,353 (M"M~'+ H20) 7.2, 352 (M7'+ H20) 0.4,336 (M8'+) are "F NMR, @: -83.80m CF2, -88.44m CF2, -124.87d CF2 0.5,334 (M~'+)0.3,249 (M'" - S02Na)2.0,247 (M~'+- S02Na) (Jp-= ~ 87.89 HZ), -137.49d CF2H ( J F - ~= 52.40Hz); I3PNMR, 6: 1.7, 149 ((C2H50)2P(O)C') 13.9, 137 ((C2H50)2P(O)+) 5.3, 87 0.12t ( J P - ~= 87.89 HZ); 'H NMR, 6: 1.33t CH3 ( J H - = ~ 7.15 HZ), (S02Naf) 1.9,65 (P02H2+)100,63 (PO2+)13.7. All other fragments 4.37mCH2, 5.83ttCFzH (JF-H = 2.94 Hz); MS (CI, m / e (species) %): are consistent with the isotope ratio expected for 13. 355 (M+ + 1) 84, 335 (M+ - F) 12, 327 (Mf + 1 - C2H4) 82, 299 (Mf + 1 - C4Hs) 100, 279 (M' + 1 - C4H9F) 60, 137 Preparation of (C2H50)2P(0)CFBrS03Na,14 ((C2H50)2(O)P+) 50, 109 ((HO)(0)P(OC2H5)+)71. A sample of 5 g (14.9 rnmol) of (C2H50)2P(0)CFBrS02N and 5 mL of water were placed in a 25-mL flask. Then 2.95 g of hydrogen Preparation of H(CFr)40(CF2)2 P ( 0 )(OH)2, 10 peroxide (30%) (molar ratio (C2H50)2P(0)CFBrS02Na:H202 = A mixture of 0.30 g H(CF2)40(CF2)2P(0)(OC2Hs)2 (0.66 mmol) 1: 1.75) was addedat O°C. The mixture was stirred at room temperature and 1.0 g Me3SiBr (6.5 mmol) was stirred vigorously at room for 5 h and then filtered. The filtrate was evaporated under reduced temperature for 24 h and at 50°C for 8 h. After reaction all volatiles pressure to give the crude product. After repetitive extraction with were removed under vacuum. One millilitre of water was added, and acetonitrile and filtering to remove small amounts of solids, the filtrate the mixture was stirred vigorously at room temperature for 16 h was evaporated to dryness under reduced pressure to give 3.92 g of followed by extraction with ether. Excess water was removed in vacuo (C2H50)2P(0)CFBrS03Na(74.8% yield). Spectral data are "F NMR, to give the crude product. The product was dissolved in water and @: -128.46d (JF-p = ?8.13 HZ); 3 1 ~ { ~6:} 6.30d; , 'H NMR, 6: stirred with a small amount of charcoal at room temperature for 2 h 1.43t (3H, J H H = 6.96 HZ), 4.41~1 (lH), 4.49~1 (1H) (JH-p = to remove color. Finally, the solution was filtered, and evaporated 7.14 Hz); MS (FB', solv. glycerol, m / e (species) 70): 375 (M"+ in vacuo at 70°C to give 0.21 g of colorless viscous oil 10 (0.38 mmol). Na) 66.6, 374 (M"M~'+ + Na) 4.5, 373 (M~'+ + Na) 66.3, The yield is 58%. Spectral data are "F NMR, @: -84.32m 0CF2, 149 ((C2H50)2P(0)C+) 10.3, 137 ((C2H50)2P(0)+) 5.5, 121 -127.36d CF2 ( J P - ~= 79.17Hz), -127.88111 CF2, -130.77m CF2, (S03Na.H20+) 2.0, 109 (C2H603Pf) 10.2, 103 (S03Na+)2.0, 65 -139.31d CF2H (JF-H = 53.71 Hz); 3 ' ~6: -4.00t; ~ ~ 'HNMR, ~ , (P02H2+)100, 63 (PO2+) 17.3. 6: -6.48tt CF2H ( J F - ~= 5.31 HZ), 8.61s P(O)(OH)2; MS (CI, m / e (species) %): 399 (M' + 1) 100, 379 (M+ - F) 33, 181 Preparation of (C2H50)2P(0)CFHS03Na, 15 ((OH)2P(O)CF2CF2+) 7 1, 8 1 ((H0)2P(O)+) 57. Activated zinc dust and 5.95 g of 14 (16.9 mmol) were reacted in dry tetrahydrofuran for 6 h at 60°C under dry nitrogen. After THF was Preparation of H(CF2)20(CF2)4P(0)(OH)2, 11, and H(CF2)20removed from the reaction mixture under reduced pressure, the residue was hydrolyzed with water at room temperature for 4 h. An aqueous (CF2)2P(O)(OH)r, 9 The method of preparation is the same as that described above for 10. solution of 15 was obtained. The solvent was evaporated under reduced Spectral data for 11 are "F NMR, @: -82.47m 0CF2, - 122.47d CF2 pressure to give a white solid. After washing with acetonitrile and (JP-= ~ 79.18Hz), -124.81mCF2, -128.69mCF2, -138.18dCF2H acetone, the white solid was dried under vacuum at 70°C for 2 h to (JF-H = 48.83 HZ); 3 1 NMR, ~ 6: -4.61t; I H NMR, 6: 7.13tt CF2H yield 2.24 g of 15 (48.6% yield). Spectral data are "F NMR, @: (JF-, = 5.50 Hz), 9.15s P(O)(OH)2; MS (CI, m / e (species) %): 399 -197.96dd (JF-p = 73.24Hz, JF-H = 43.94Hz); 31P{H},6: 10.43d; (M' 1) 63, 181 ((H0)2P(0)CF2CF2') 31, 81 ((H0)2P(O)+) 100. 'H NMR, 6: 1.42t (6H, J H -=~ 7.15 HZ), 4.32q (2H), 4.41q (2H) Spectral data for 9 are "F NMR, @: -84.44111 CF2, -89.42m CF2, (JH-p = 7.85 HZ), 5.72dd (1H) (JH-p = 5.5 HZ); MS (m+,S O ~ V . -127.30dCF2(Jp-F = 87.89 HZ),-139.46dCFzH ( J F - ~= 48.83 HZ); glycerol H20, m / e (species) %): 295 (M' + Na) 100,289 (Mf + H20 3 1 NMR, ~ 6: -1.82; IH NMR, 6: 6.21tt CF2H ( J H - = ~ 2.94 HZ), - 1) 1.5, 273 (M' + 1) 16.8, 149 ((C2H50)2P(0)Cf) 1.9, 137 11.03s P(O)(OH)2;MS (CI, m / e (species) %): 299 (M+ 1) 100,279 ((C2H50)2P(0)+)4.6, 65 (P02H2') 14.7, 63 (P02') 3.9. (M' - F) 50, 181 ((HO)2P(O)CF2CF,+) 90, 81 ((H0)2P(O)') 51. Preparation of (HO)2P(0)CFHS03Na,I6 Preparation of (C2H50)zP(0)CFBr2,12 A mixture of 2.24 g of (C2H50)2P(0)CFHS03Na(8.2 mmol) and Tribromofluoromethane (27.1 g, 0.1 mol) was slowly added to 5 g of hydrochloric acid (12 N) were stirred vigorously at 120°C for triethylphosphite (16.6 g, 0.1 mol) at 0°C under a nitrogen atmosphere 10 h. The reaction mixture was filtered and the filtrate was evaporated and then stirred continuously at 0°C for 4 h. The reaction mixture was to dryness under vacuum to obtain a crude product that was taken up in distilled under reduced pressure to yield 25.24 g (76.9%) of diethylCH3CN. A small quantity of solid was removed by filtration. After dibromofluoromethylphosphonate (bp 86-87"C/0.7 Torr). Spectral removal of the solvent under vacuum, a white solid was obtained. This = 78.12 Hz); 1 3 p { ~NMR, } 6: data are 'F NMR, @: -75.98d process was repeated twice. The product was taken up in water, and 1.51d; 'H NMR, 6: 1.38t (3H, J H -=~6.96 HZ), 4.32q (lH), 4.41q methylene chloride was added. The mixture was stirred vigorously (1H) (JH-p = 8.03 Hz); MS (FB , solv. glycerol, m / e (species) %): for 1 h. The water phase was collected and evaporated under reduced 331 (M'" 1) 5.4,329 (M"M~'+ 1) 10.5,327 (M~'+ 1) 6.02, pressure at 80°C to yield 1.07 g of 16 (59.4% yield). Spectral data 250 (M'" + 1 - Bra') 1.83, 248 (M7'+ + 1 - Br7') 1.5, 193 ~ 48.82 Hz); are 'F NMR, @: - 194.25dd (JF-p = 68.85 Hz, J F - = (cFB~~'") 6.9, 189 ( C F B ~ ~ )~6.9, ' + 168 (C2H50)P(0)CF+)1.1, 149 31P{H}NMR, 6: 6.91d; 'H NMR, 6: 4.90dd CH (JH-p = 5.13 HZ), (C2H50)2P(0)C') 6.7, 137 (C~HSO)~P(O)') 29.4, 112 (CFB~"+) 8.58s OH; MS (FB' , glycerol, m / e (species) %): 215 (Mf - 1) 19.9, 2.4, 110 (cFBr7'+) 3.0, 65 (H202P') 100, 63 (P02+) 4.9. All other 193 (M' - Na) 79.9,175 (Mf - Na - H20)29.3, 113 (Mf - S03Na) fragments are consistent with the isotope ratio expected for 12. 9.1, 112 ((HO),P(O)CF+) 1.5, 111 (CHFP03') 4.4, 91 (CP03+)

@: -83.45m 0CF2, - 124.64d CF2 (JP-F = 87.97 Hz), - 127.07m CF2, -129.79mCF2, -137.11dCF2H(JF-H = 53.71 HZ); I 3 p ~ M ~ 6: -0.36t; 'H NMR, 6: 1.40t CH3 ( J H - ~= 6.96 Hz), 4.34m CH2, 6.16tt CF2H ( J F - ~= 53.71 Hz, J F - H = 5.5 Hz). Spectral data for HCF2CF20CF2CF2CF2CFzP(0)(OC2H5)2 (bp 126"C/0.5 Torr) are "FNMR, @: -84.27m CF2, -84.79111 CF2, - 123.94d CF2 ( J P - ~ = 87.97 Hz), - 126.61111 CF2, - 130.77111CF2, -139.75d CF2H ( J F - ~ = 48.83 Hz); 31PNMR, 6: - 1.09t.

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Preparation of (H0)2 P(0)CFHS03H, 17 An aqueous solution of 0.8 g of (H0)2P(0)CFHS03Na(3.7 mmol) was passed through an Amberlite IR-120 ion exchange resin at a flow rate of approximately 2 mL/min. The volume of the aqueous acid was reduced by evaporation, and the crude product was dried under reduced pressure at 50-80°C for 4 h. The product was dissolved in water and 0.1 g of charcoal was added. The mixture was stirred at 50°C for 2 h. Charcoal was removed by filtration, and the filtrate was evaporated under vacuum at 80°C for 4 h to yield 0.57 g of (H0)2P(0)CFHS03H (79.2% yield). The solid melts at 115-1 16'C, and is very hygroscopic. ~ @: - 193.67dd (JF-p = 68.36 Hz, J F -=~ Spectral data are 1 9NMR, 48.83 HZ);3 1 ~ { HNMR, ) 6: 6.55d; 'H NMR, 6: 4.89dd CH (JH-p = 5.13 Hz), 12.18(s) OH; MS (CI+, m/e (species) %): 213 (M+ + H20 + 1) 0.3, 113 (M+ - S03H) 1.O, 81 (S03H' or (H0)2P(0)+) 52.7,80 (P03H+) 1.5,79 (PO3+)3.1,65 (P02H2+)100,64 ( P 0 2 ~ + ) 4.1, 59 (P(O)C+) 1.5. Anal. calcd. for CH4F06PS: C 6.19, H 2.06, F9.79, S 16.52;found: C6.20, H2.10, F9.90, S 16.36.

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Preparation of (C2H50)2P(0)CF(S03Na) (S02Na), 18, and (C2H50)2P(0)CF(S03Na)2, 19 In a 25-mL three-necked, round-bottomed flask were placed 1.49 g of Na2S204 (8.6 mmol), 0.72 g of NaHC03 (8.6 mmol), 2 g of (C2H50)2P(0)CFBrS03Na(5.7 mmol), 6 mL of water, and 6 mL of CH3CN. Under a stream of nitrogen, the contents were stirred vigorously at 0°C for 4 h. The reaction mixture was filtered and the filtrate was evaporated to dryness under reduced pressure to give crude (C2H50)2P(0)CF(S03Na)(S02Na). Spectral data are ' 9 NMR, ~ @: -165.784 (JF-p = 73.24 Hz); "P{H), 8: 9.76d; 'H NMR, 6: 1.411 (3H, J H - = ~ 6.96 HZ), 4.32q (lH), 4.40q (1H) (JH-p = 7.23 HZ); MS (FAB, solv. glycerol, m/e (species) %): 395 (M+ + 1 + 2H20) 1.3.376 (M+ + H20) 1.6,330 (M+ + 1 - C2H5)3.3,313 (M+ + 1 2Na) 4.1, 271 (Mi - S02Na) 4.1, 255 (Mi - S03Na) 0.9. 168 ((C2H50)2P(0)CF') 5.3, 149 ((C2H50)2P(O)C+) 29.2, 137 ((C2H50)2P(0)+)18.9, 108 (C2H503P+)8.3, 105 (S02Na.H20+) 13. I , 103 (S03Na') 2.2, 64 (P02H+) 100, 63 (PO2+)36.2. Crude (C2H50)2P(0)CF(S03Na)(S02Na) and 5 mL of water were placed in a 25-mL flask. Then hydrogen peroxide (30%) (molar ratio 18:H202 = 1:l) was added at - 15'C, and the mixture was stirred for 1 h. After concentrating and cooling, the inorganic solid impurities were removed by filtration. The filtrate was evaporated under reduced pressure to give crude 19. The crude product was extracted with acetone three times. The acetone extract was collected and evaporated at reduced pressure to give 0.71 g (32%) of pure (C2H50)2P(0)CF(S03Na)2. Spectral data are ' 9 ~NMR, @: - 151.82d (JF-p =

73.24 HZ);3 1 P { ~NMR, ) 6: 7.82d; IH NMR, 6: 1.39t (3H, J H -=~ 6.97 HZ),4.32q (lH), 4.41q (1H) (JH-p = 8.04 HZ);MS (FAB, ~ 0 1 ~ . glycerol, m/e (species) %): 410 (M+ + 2H20) 3.0, 330 (M+ + 1 0C2H5)8.1, 271 (M+ - S03Na) 2.5, 168 (M+ - 2S03Na) 4.0, 149 (C2H50)2P(0)C') 24.9, 137 ((C2H50)2P(0)+)14.5, 121 (SO3Na' + H20) 2.2, 109 (C2H603p+)14.3, 103 (S03Na+) 3.1, 65 (P02H2+) 1.4.64 (P02H+) 100, 63 (PO2+)55.3. Titration Titration of the acids was monitored utilizing an Orion model 701A digital Ionalyzer and Coming combination pH electrode. Sodium hydroxide was standardized with primary standard potassium acid phthalate. Tetrabutylarnrnonium hydroxide in toluene/methanol solution was prepared from tetrabutylarnmonium iodide (12) and standardized against primary standard benzoic acid in dimethyl formamide.

Acknowledgments Acknowledgment is made to the donors of the Petroleum Research Fund administered by the American Chemical Society, to NSF CHE-8703790, to AFOSR 87-0067, and to the Gas Research Institute for support of this work. H. ROTROWSKA, and M. H. ALDRIDGE.J. 1. C. BUNYAGLDJ, Chem. Eng. Data, 26, 344 (1981). 2. D. B. Su, J. Y. CHEN,R. X. ZHU, and H. P. Hu. Huaxue Xuebao, 41,946 (1983). 3. W. Y. HUANG,B. N. HUANG, and C. M. Hu. J. Fluorine Chem. 23, 193 (1983). 4. R. D. HOWELLS and J. D. M c C o w . Chem. Rev. 77,69 (1977). 5. W. B. CEN,Z. X. DONG,T. J. HUANG,D. B. SU, and J. M. SHREEVE. Inorg. Chem. 27, 1376 (1988). and J. M. SHREEVE. Inorg. Chem. 25,3830 (1986). 6. T. MAHMOOD 7. T. MAHMOOD and J. M. SHREEVE. Inorg. Chem. 25,4081 (1986). 8. T. MAHMOOD and J. M. SHREEVE. Synth. Commun. 17, 71 (1987). 9. D. J. BURTON,L. G. SPRAGUE, D. J. RETRZYK, and S. H. EDELMUTH. J . Org. Chem. 49, 3437 (1984); 53, 1523 (1988). A. S. MODAK, R. GUNERATNE, D. SU,W. CEN, 10. D. J. BURTON, R. L. KIRCHMEIER, and J. M. SHREEVE. J. Am. Chem. Soc. 111, 1773 (1989). 11. Perfluoro Sulfonic Acid Group, Shanghai Institute of Organic Chemistry. Acad. Sin. Sci. Sin. (Engl. Ed.) 21, 773 (1978). 12. United States Pharmacopeial Convention. United States Pharmacopeia/National Formulary XX(XV) 1980. p. 1113.