For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose acetate and polyacrylonitrile.\ud
\ud
The results showed that cellulose and cellulose acetate could be modified by a direct reaction of 1.3 propane sultone with the available hydroxyl groups. The nitrile groups in polyacrylonitrile had to be reacted first with hydrogen sulphide to give reactive thioamide groups, able to react with the sultone. These results give evidence for 1.3 propane sultone being a useful chemical for modification of polymers, its carcinogenic properties will however prevent application

Bantjes, A.

Rupkema, B.

Smolders, C.A.

Velden, P.M. van der

English

Abstract--For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose adetate and polyacrylonitrile. The results showed that cellulose and cellulose acetate could be modified by a direct reaction of 1.3 propane sultone with the available hydroxyl groups. The nitrile groups in polyacrylonitrile had to be reacted first with hydrogen sulphide to give reactive thioamide groups, able to react with the sultone. These results give evidence for 1.3 propane sultone being a useful chemical for modification of polymers, its carcinogenic properties will however prevent applications

P. M. Van Der Velden

B. Rlipkema

C. A. Smolders

A. Bantjes

CiteSeerX

REACTIONS WITH 1.3 PROPANE SULTONE FOR THE SYNTHESIS OF CATION-EXCHANGE MEMBRANES

For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose acetate and polyacrylonitrile. The results showed that cellulose and cellulose acetate could be modified by a direct reaction of 1.3 propane sultone with the available hydroxyl groups. The nitrile groups in polyacrylonitrile had to be reacted first with hydrogen sulphide to give reactive thioamide groups, able to react with the sultone. These results give evidence for 1.3 propane sultone being a useful chemical for modification of polymers, its carcinogenic properties will however prevent application

van der Velden, P.M.

University of Twente Research Information

European Polymer Journal, Vol. 13, pp. 37 to 39. Pergamon Press 1977. Printed in Great Britain. REACTIONS WITH 1.3 PROPANE SULTONE FOR THE SYNTHESIS OF CATION-EXCHANGE MEMBRANES P. M. VAN DER VELDEN*, B. RLIPKEMA, C. A. SMOLDERS and A. BANTJES Twente University of Technology, Department of Chemical Engineering, P.O. Box 217, Enschede, The Netherlands (Received 26 April 1976) Abstract--For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose adetate and polyacrylonitrile. The results showed that cellulose and cellulose acetate could be modified by a direct reaction of 1.3 propane sultone with the available hydroxyl groups. The nitrile groups in polyacrylonitrile had to be reacted first with hydrogen sulphide to give reactive thioamide groups, able to react with the sultone. These results give evidence for 1.3 propane sultone being a useful chemical for modification of polymers, its carcinogenic properties will however prevent applications. INTRODUCTION The most important polymers for the preparation of hyperfiltration and ultrafiltration membranes now seem to be cellulose acetate, polyarnides and polyac- rylonitrile. Since introduction of negatively charged groups in these types of polymers may offer some interesting possibilities, e.g. reduced membrane foul- ing and increased selectivity, we studied the reaction between 1.3 propane sultone and some of these polymers. Reactions with 1.3 propane sultone are favoured since strongly anionic groups are intro- duced. Moreover 1.3 propane sultone is very reactive; all reactions proceed at room temperature. Several authors used 1.3 propane sultone for the modification of cellulose into ion-exchangers, flocculants, adhe- sives [1] or for the preparation of cation-exchange membranes [2, 3]; 1.3 propane sultone was also used for the modification of polyamides [1, 4] and for ring- opening polymerization with tertiary amines [5]. The synthesis of sodium sulphopropyl cellulose from alkali cellulose was studied by both Rozelle et al. [2,3] (solid state reaction) and Goethals and Natus [6] (reaction in indifferent solvents): C ~ H 2  Rol t r (OH}NoOH+CH 2 0 ~ RcelI-O-CH~'CH~-CH:TSO3No+H20 Rozelle et aL synthesized cellulose acetate-O-propyl sulphonic acid by a second reaction between the un- reacted hydroxyl groups of sodium sulphopropyl cellulose and acetic anhydride. Membranes prepared from this polymer showed excellent performance: a flux of 6 cm3/cm 2 hr and rejections of 96% total dis- solved solids, 94% ammonia and 86% total organic carbon[2].  Although the possibility of preparing cellulose acetate-O-prow1 sulphonic acid directly from cellulose acetate was mentioned, no results were reported. With polyacrylonitrile, 1.3 propane sultone can also be used for the introduction of anionic groups, since Gabrielyan and Rogovin [7] have found that the nitrile group can easily be converted into a thioamide group using hydrogen sulphide. The tautomeric equi- librium between the thioamide group and the thiol form offers a possibility to introduce sulphonate groups, since the - S H  group reacts with 1.3 propane sultone according to Fischer [1] (Fig. 1). EXPERIMENTAL The starting polymers were cellulose (Schuchardt), cellu- lose acetate (Eastman Kodak E-38.3) and polyacrylonitrile (Orlon/Du Pont). The 1.3 propane sultone was supplied by Aldrich. Infra-red spectra were made with a Beckman LR.-33 spectrophotometer and the P.M.R. spectra with a Varian XL 100 spectrophotometer. RESULTS I. Cellulose and cellulose acetate The reactions between cellulose and 1.3 propane sultone were carried out at room temperature in acetone with 7.7 wt~o cellulose and with a ratio of one mole 1.3 propane sultone per mole hydroxyl group. The reaction was completed by adding a large excess of sodium hydroxide solution to the reaction mixture. After 14hr the conversion was very low; (~) CN ~CH 2 - CH~ n ~=NH 1 . 3  pro0one Sult0ne I (CHz) 3 S03H "( CH 2 - CH ~'r, 1L ~ CH 2-  CIH t" n C'NH I SH (r) 37 * Present address: Cordis Dow B.V., Roden, The Neth- Fig. 1. Reaction sequence for the modification of erlands, polyacrylonitrile. 38 P. M. VAN DER VELDEN et al. Table 1. Elemental weight percentages in various cellulose-derivatives Element Polymer C H O Na S Total Cellulose 43.74 6.38 50,25 - -  - -  100.37 Sodium sulphopropyl cellulose 34.11 5.32 44.42 7.23 9 .49  100.57 Cellulose acetate 48.45 5.74 46.13 - -  - -  100.32 Cellulose acetate-O-propyl sulphonic acid 45.05 5.63 45.54 1.83 2 .73  100.78 however after 120 hr the degree of substitution was 0.83 (Table 1). In the i.r. spectrum of the reaction product, there was a new strong absorption at 1190 cm-  1 due to the - SO3Na group. Proton mag- netic resonance spectra of the reaction product dis- solved in 20 wt~ DCI/D:O showed broad bands at f-values of ca. 2.2, 3.2 and 3.9 ppm. By comparison of these data with those of cellulose, we conclude that the P.M.R. results agree with the elemental analysis given in Table 1 and that the reaction product was sodium sulphopropyl cellulose. Since synthesis of cellulose acetate-O-propyl sul- phonic acid by acetylation of sodium sulphopropyl cellulose to full substitution [3] is a rather complex way to prepare anionic cellulose acetate, we studied the direct reaction between the hydroxyl groups in partially substituted cellulose acetate (C.A.) and 1.3 propane sultone. Although the hydroxyl groups in C.A. should be more easily attacked by 1.3 propane sultone than those in cellulose (C.A. being soluble in acetone), none of the i.r. spectra from the reaction products were clearly different from that of C.A. However, according to elemental analysis, small con- versions were obtained after 64 hr at room tempera- ture and neutralization with an equimolar amount of sodium bicarbonate (Table 1). 2. Polyacrylonitrile Polyacrylonitrile (PAN) can be modified through reactions with the nitrile group, e.g. by reaction with hydrogen sulphide[7] or by alkaline saponifica- tion [8]. Since the first reaction is commonly cata- lyzed by organic bases like pyridine and triethyla- mine, we studied the influence on the conversion of l o  mo~ ratio SIN vol% (C=Hsh N O 10 2O | I 0.5- 0 rlaction time (hours) D. Fig. 2. Degree of modification of polyacrylonitrile with hy- drogen sulphide. (a) As a function of reaction time in the presence of 20 vol ~ (C2Hs)3N as catalyst; (b) After 2½ hr reaction time as a function of the amount of catalyst present during the reaction. the amount of triethylamine present during the reac- tion (Fig. 2). All reactions were carried out in a 10Wt~o polymer solution in dimethylformamide at 50 ° and were finished after 2½ hr since it was shown that the maximum conversion had been reached (Fig. 2). Infra-red spectra of the reaction products showed an absorption at 1624 cm-1, indicating the presence of thioamide groups [7]. These results indicated that reaction between PAN and hydrogen sulphide does proceed; the conversions found with different volume percentages of catalyst are quite high. For mem- branes, which are not chemically crosslinked, only small conversions are possible in order to maintain mechanical strength and to prevent the polymer becoming water-soluble. For these reasons, all further reactions were carried out without catalyst. Analo- gous to the experiments with cellulose and cellulose acetate, the reaction with excess 1.3 propane sultone takes place in acetone, which is a non-solvent for products (I) (Fig. 1). Sulphonic acid groups were in- troduced by quantitative reaction of the - SH groups with 1.3 propane sultone, as concluded from elemen- tal analysis of the reaction products (Table 2). Ion exchange capacity measurements by potentiometric titration gave results in good agreement with these elemental analyses (Table 2). Finally, viscometric ex- periments on PAN and the products listed in Table 2 showed a constant intrinsic viscosity for PAN and for the neutral polymers (IA) and (IB) in dimethylfor- mamide, while the intrinsic viscosity of the polyelec- trolytes (IIA) and (IIB) more than doubled. This vis- cometric behaviour also provides support for ionic character of polymer (II). From these results, we conclude that the results of the reactions with hydrogen sulphide and 1.3 pro- pane sultone, confirm the reaction sequence in Fig. 1. Carcino.qenity of  1.3 propane sultone Although 1.3 propane sultone belongs to the group of alkylating chemicals, a group known to have car- Table 2. Elemental analyses of polyacrylonitrile derivatives (I) after times of reaction with hydrogen sulphide from 1 hr (A) and 2 hr (B), and of their derivatives (II). (Chemi- cal compositions of I and II are given in Fig. 1.) Elemental weight Vo Ion exchange Mole ratio capacity Polymer S N S/N (meq/gr) (IA) 3.15 23.08 0.06 - -  (IIA) 5.59 19.92 0.12 0.750 (IB) 8.07 21.27 0.t7 - -  (liB) 12.26 14.69 0.36 1.906 The synthesis of cation-exchange membranes 39 cinogenic properties, for a long time 1.3 propane sultone was not recognized as a dangerous carcino- gen [9a]. However, recently rather alarming informa- tion has been published: 1.3 propane sultone pro- duced tumours in rats, rabbits and mice when given orally, subcutaneously or by intravenous administra- tion, resulting in death of a high percentage of these animals [9b, 12, 13-1. Although any contact with the skin in handling 1.3 propane sultone should always be avoided [1, 9b], the carcinogenic activity found for animals was exceptionally high and total prohibition of the use of 1.3 propane sultone in industry was advised [ 14]. Recently, the use, transport and possession of 1.3 propane sultone has been forbidden in the Nether- lands [15]. Since the propyl group is not functional in our experiments, higher homologues may be used, e.g. 1.4 butane sultone, found to be much less carcino- genic I l l ,  13]. However, these homologues are not commercially available, are less reactive and effect lower conversions. CONCLUSION Although 1.3 propane sultone is a unique chemical by which anionic groups can be introduced in cellu- lose-derivatives, polyamides and polyacrylonitrile, the carcinogenic properties will prevent any industrial large scale application. Since higher homologues are less carcinogenic, 1.3 propane sultone may be re- placed by a higher homologue in the reaction given above. Acknowledgement--The authors thank Mr. W. Lengton for assistance with the potentiometric titrations. REFERENCES 1. R. F. Fischer, Ind. Engng Chem. 56 (3), 41 (1964). 2. North Star Research and Development Institute. Water pollution control research series, Report 17020 EFA 10/70 (1970). 3. L. T. Rozelle, J. E. Cadotte, B. R. Nelson and C. V. Kopp, Appl. Polym. Syrup. 22, 223 (1973). 4. D. Dieterich, W. Keberle and H. Witt, Angew. Chem. 82, 53 (1970). 5. S. Hashimoto and T. Yamashita, Polymer Journal 8, 15 (1976). 6. E. J. Goethals and G. Natus, Makromolek. Chem. 93, 259 (1966). 7. G. A. Gabrielyan and Z. A. Rogovin, Vysokomolek. Soedin. 6 (5), 759 (1964). 8. H. Bayzer and J. Schurz, Z. phys. Chem. N.F. 13, 30 (1957). 9. N. I. Sax, Dangerous Properties of Industrial Materials, Van Nostrand, Reinhold, New York (a) 3rd ed. (1968); (b) 4th ed. (1975). 10. B. L. van Duuren, S. Melchionne, R. Blair, B. M. Goldschmidt and C. Katz, J. hath. Cancer Inst. 46 (1), 143 (1971). 11. H. Druckrey, H. Kruse, R. Preussmann, S. Ivankovic, Ch. Landschiitz and J. Gimmy, Z. Krebsforsch. 75, 69 (1970). 12. U. W61cke, Chemische Carcinogene im Laboratorium, Bundesanstalt Rir Arbeitsschutz und Unfallforschung, Dortmund (1974). 13. G. W. Fischer, R. Jentzsch, V. Kasanzewa and F. Riemer, J. prakt Chem. 317, 943 (1975). 14. R. Audran and G. Siou, Cah. Notes docum. 81, 467 (1975). 15. J. Government of the Netherlands ("Staatsblad"), no. 97, l l  March 1976. 

Reactions with 1.3 propane sultone for the synthesis of cation-exchange membranes

Chemische Carcinogene im Laboratorium, Bundesanstalt Rir Arbeitsschutz und Unfallforschung,

Dangerous Properties of Industrial Materials,

Government of the Netherlands (&quot;Staatsblad&quot;),

Research and Development Institute. Water pollution control research series,

https://doi.org/10.1016/0014-3057(77)90045-3

Reactions with 1.3 propane sultone for the synthesis of cation-exchange membranes

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