A general synthesis of 1-alkyl-4-vinylpyridinium ions. Alkylation of 4-vinylpyridine
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5610
J . Org. Chem. 1990, 55, 5610-5613
A General Synthesis of 1-Alkyl-4-vinylpyridinium Ions. Alkylation of 4-Vinylpyridine with Primary Alkyl Triflates
Received March 12, 1990
1-Alkyl-4-vinylpyridinium trifluoromethanesulfonates, prepared by alkylation of 4-vinylpyridine with trifluoromethanesulfonate (triflate) esters of primary alcohols (ROTf) in dry dichloromethane a t 0 "C, are stable, storable salts. The protium, methyl, and dodecyl salts have been isolated as crystalline solids. The ethyl, butyl, and hexyl analogues are usually obtained as viscous liquids. All of these salts readily polymerize to the related poly(1-alkyl-4-vinylpyridinium triflate) when heated to melting (-68-122 "C) or when treated with radical (AIBN) or base (pyridine) initiators. The alkylating abilities of triflate esters toward 4-vinylpyridine in CDC1, and/or DMSO-d, a t 20-23 O C have been compared with those of common methylating agents: CH,OTf, CzH50Tf> C4H90Tf,C6H130Tf, ClzHvOTf> (CH3)&04> CH31, CH30S0zC6H4-p-N0z > CH30S0zC6H4-p-CH,. Alkylation with C2H&S0zC6H4-p-CH, under similar conditions gave poly( 1-ethyl-4-vinylpyridinium tosylate).
(h)
(I)
R = CH3. X- = pN@C&S03R = CHj, X. = pCH3C&SOj
0)
R = CH3, X' = 1
H, X- = Br-, C1-, C104-, HS04-, NO,-), has also been prepared and characterized in several l a b ~ r a t o r i e s . ' ~ - ~ ~ Past attempts to extend N-alkylation of 4-vinylpyridine (4)to higher homologues have been unsuccessful. For example, Kabanov and co-workers could isolate only 2 (R = CH2CH3, X- = Br-) when 4 was treated with ethyl bromide under a variety of conditions.12* We, like Salamone, Kabanov, and others, have assumed that the lack of generality in previous synthetic procedures for 1 was due to an unfavorable competition between N-alkylation of 4 and base-initiated polymerization of 1, eq 2. If alkylation of 4 is slow compared to polymerization
(1)(a) Strauss, U.P.; Gershfeld, N. L. J . Phys. Chem. 1954,58, 747. (b) Strauss, U.P.; Gershfeld, N. L.; Crook, E. H. J . Phys. Chem. 1956, 1390. 60,577.( c ) Strauss, U.P.; Williams, B. L. J . Phys. Chem. 1961,65, (d) Strauss, U.P. In Micellization, Solubilization and Microemulsions; Mittal, K. L., Ed.; Plenum Press: New York, 1977;Vol. 2, pp 895-900. (2)(a) Fendler, J. H. Membrane Mimetic Chemistry; John Wiley and Sons: New York, 1982;pp 209-223. (b) Fendler, J. H. In Surfactants in Solution; Mittal, K. L., Lindman, B., Eds.; Plenum Press: New York, 1982;Vol. 3,pp 1947-1989. (3)Menger, F. M. In Topics in Current Chemistry; Springer-Verlag: Berlin, 1986;Vol. 136. (4)(a) Okubo, T.; Ise, N. J. Org. Chem. 1973,38,3120. (b) Okubo, T.; 1973,95,2293. (c) Kitano, H.; Tanaka, M.; Ise, N. J . Am. Chem. SOC. Okubo, T. J . Chem. SOC.Perkin Trans. N 1976, 1074. (5) Rodulfo, T.; Hamilton, J. A.; Cordes, E. H. J. Org. Chem. 1974,39, 2281. Yu, E. K.; Kabanov, V. A. Vysokomol. Soedin. (6)Starodubtsev,S.G.; 1974,A16, 2360. (7) (a) Kunitake, T.; Shinkai, S.; Hirotsu, S. J . Polym. Sci. Polym. Lett. Ed. 1975,23,377. (b) Shinkai, S.; Kunitake, T. Biopolymers 1976, Shinkai, S.; Hirotsu, S. Biopolymers 1976,15, 15,1129. (c) Kunitake, T.; 1143. (d) Kunitake, T.; Shinkai, S. Adu. Phys. Org. Chem. 1980,17,435. (e) Shinkai, S.;Hirakawa, M.; Shimomura, M.; Kunitake, T. J . Org. Chem. 1981,46,868. (8)Skorodinskaya, A. M.; Kemenova, V. A.; Chernova, 0. V.; Efimov, V. S.; Lakin, K. M.; Zezin, A. B.; Kabanov, V. A. Khim.-Farm. Zh. 1983, 17, 1463. (9)Daido, T.; Yura, H.; Ishida, M.; Akaike, T. Kobunshi Ronbunshu 1985,42,705;Chem. Abstr. 1986, 104, 48186. (10)Degani, Y.; Heller, A. J . Am. Chem. Soc. 1989,ZlZ, 2357. (11)Kasem, K. K.; Fife, W. K.; Zeldin, M.; Leidner, C. R. J . Electroanal. Chem. In press.
'百度文库'+
R
x
'I.+
R
x
3
1
2
R = H. X'
(a)
=TO
(b)
(c)
R = CH3, X' = T O
R = CZHS. X- = T O
R = CqH9. X' = T O -
(d)
(e)
R = CgHi3. X- = TO R
= ClzH25.
(0
lg)
X- = T O
R = CH3. X - = CHjOSO3
1-Alkyl-4-vinylpyridinium ions (A4VP, 1) are potentially important precursors to poly( 1-alkyl-4-vinylpyridiniums) (PA4VP, 2), eq 1. PA4VP are well-known, versatile polymeric materials. They have been widely studied and have found use as polyelectrolyte^,^-^ surfactants,'2 enzyme mimics;-' and immobilization media for biomolecules and electroactive assemblies.&" Synthesis of 2 has usually been accomplished by alkylation of poly(4-vinylpyridine) (P4VP, 3), eq 1. This convenient method only becomes limiting when complete alkylation of pyridine residues or introduction of two or more different N-alkyl groups becomes an issue. In these cases, polymerization of l, either one kind of monomer or mixtures of monomers with different alkyl groups, assures formation of completely alkylated 3 with single or multiple alkyl groups as desired. Although there is considerable literature precedent for synthesis and polymerization of 1, only l-methyl-4vinylpyridinium salts among the many possible simple N-alkylated variants have been reported as stable, isolated compound^.'^-'^ The protonated analogue, 1 (e.g.; R =
Wilmer K. Fife,* Prema Ranganathan, and Martel Zeldin
Department of Chemistry, Indiana University-Purdue University at Indianapolis, 1125 East 38th Street, Indianapolis, Indiana 46205
J . Org. Chem. 1990, 55, 5610-5613
A General Synthesis of 1-Alkyl-4-vinylpyridinium Ions. Alkylation of 4-Vinylpyridine with Primary Alkyl Triflates
Received March 12, 1990
1-Alkyl-4-vinylpyridinium trifluoromethanesulfonates, prepared by alkylation of 4-vinylpyridine with trifluoromethanesulfonate (triflate) esters of primary alcohols (ROTf) in dry dichloromethane a t 0 "C, are stable, storable salts. The protium, methyl, and dodecyl salts have been isolated as crystalline solids. The ethyl, butyl, and hexyl analogues are usually obtained as viscous liquids. All of these salts readily polymerize to the related poly(1-alkyl-4-vinylpyridinium triflate) when heated to melting (-68-122 "C) or when treated with radical (AIBN) or base (pyridine) initiators. The alkylating abilities of triflate esters toward 4-vinylpyridine in CDC1, and/or DMSO-d, a t 20-23 O C have been compared with those of common methylating agents: CH,OTf, CzH50Tf> C4H90Tf,C6H130Tf, ClzHvOTf> (CH3)&04> CH31, CH30S0zC6H4-p-N0z > CH30S0zC6H4-p-CH,. Alkylation with C2H&S0zC6H4-p-CH, under similar conditions gave poly( 1-ethyl-4-vinylpyridinium tosylate).
(h)
(I)
R = CH3. X- = pN@C&S03R = CHj, X. = pCH3C&SOj
0)
R = CH3, X' = 1
H, X- = Br-, C1-, C104-, HS04-, NO,-), has also been prepared and characterized in several l a b ~ r a t o r i e s . ' ~ - ~ ~ Past attempts to extend N-alkylation of 4-vinylpyridine (4)to higher homologues have been unsuccessful. For example, Kabanov and co-workers could isolate only 2 (R = CH2CH3, X- = Br-) when 4 was treated with ethyl bromide under a variety of conditions.12* We, like Salamone, Kabanov, and others, have assumed that the lack of generality in previous synthetic procedures for 1 was due to an unfavorable competition between N-alkylation of 4 and base-initiated polymerization of 1, eq 2. If alkylation of 4 is slow compared to polymerization
(1)(a) Strauss, U.P.; Gershfeld, N. L. J . Phys. Chem. 1954,58, 747. (b) Strauss, U.P.; Gershfeld, N. L.; Crook, E. H. J . Phys. Chem. 1956, 1390. 60,577.( c ) Strauss, U.P.; Williams, B. L. J . Phys. Chem. 1961,65, (d) Strauss, U.P. In Micellization, Solubilization and Microemulsions; Mittal, K. L., Ed.; Plenum Press: New York, 1977;Vol. 2, pp 895-900. (2)(a) Fendler, J. H. Membrane Mimetic Chemistry; John Wiley and Sons: New York, 1982;pp 209-223. (b) Fendler, J. H. In Surfactants in Solution; Mittal, K. L., Lindman, B., Eds.; Plenum Press: New York, 1982;Vol. 3,pp 1947-1989. (3)Menger, F. M. In Topics in Current Chemistry; Springer-Verlag: Berlin, 1986;Vol. 136. (4)(a) Okubo, T.; Ise, N. J. Org. Chem. 1973,38,3120. (b) Okubo, T.; 1973,95,2293. (c) Kitano, H.; Tanaka, M.; Ise, N. J . Am. Chem. SOC. Okubo, T. J . Chem. SOC.Perkin Trans. N 1976, 1074. (5) Rodulfo, T.; Hamilton, J. A.; Cordes, E. H. J. Org. Chem. 1974,39, 2281. Yu, E. K.; Kabanov, V. A. Vysokomol. Soedin. (6)Starodubtsev,S.G.; 1974,A16, 2360. (7) (a) Kunitake, T.; Shinkai, S.; Hirotsu, S. J . Polym. Sci. Polym. Lett. Ed. 1975,23,377. (b) Shinkai, S.; Kunitake, T. Biopolymers 1976, Shinkai, S.; Hirotsu, S. Biopolymers 1976,15, 15,1129. (c) Kunitake, T.; 1143. (d) Kunitake, T.; Shinkai, S. Adu. Phys. Org. Chem. 1980,17,435. (e) Shinkai, S.;Hirakawa, M.; Shimomura, M.; Kunitake, T. J . Org. Chem. 1981,46,868. (8)Skorodinskaya, A. M.; Kemenova, V. A.; Chernova, 0. V.; Efimov, V. S.; Lakin, K. M.; Zezin, A. B.; Kabanov, V. A. Khim.-Farm. Zh. 1983, 17, 1463. (9)Daido, T.; Yura, H.; Ishida, M.; Akaike, T. Kobunshi Ronbunshu 1985,42,705;Chem. Abstr. 1986, 104, 48186. (10)Degani, Y.; Heller, A. J . Am. Chem. Soc. 1989,ZlZ, 2357. (11)Kasem, K. K.; Fife, W. K.; Zeldin, M.; Leidner, C. R. J . Electroanal. Chem. In press.
'百度文库'+
R
x
'I.+
R
x
3
1
2
R = H. X'
(a)
=TO
(b)
(c)
R = CH3, X' = T O
R = CZHS. X- = T O
R = CqH9. X' = T O -
(d)
(e)
R = CgHi3. X- = TO R
= ClzH25.
(0
lg)
X- = T O
R = CH3. X - = CHjOSO3
1-Alkyl-4-vinylpyridinium ions (A4VP, 1) are potentially important precursors to poly( 1-alkyl-4-vinylpyridiniums) (PA4VP, 2), eq 1. PA4VP are well-known, versatile polymeric materials. They have been widely studied and have found use as polyelectrolyte^,^-^ surfactants,'2 enzyme mimics;-' and immobilization media for biomolecules and electroactive assemblies.&" Synthesis of 2 has usually been accomplished by alkylation of poly(4-vinylpyridine) (P4VP, 3), eq 1. This convenient method only becomes limiting when complete alkylation of pyridine residues or introduction of two or more different N-alkyl groups becomes an issue. In these cases, polymerization of l, either one kind of monomer or mixtures of monomers with different alkyl groups, assures formation of completely alkylated 3 with single or multiple alkyl groups as desired. Although there is considerable literature precedent for synthesis and polymerization of 1, only l-methyl-4vinylpyridinium salts among the many possible simple N-alkylated variants have been reported as stable, isolated compound^.'^-'^ The protonated analogue, 1 (e.g.; R =
Wilmer K. Fife,* Prema Ranganathan, and Martel Zeldin
Department of Chemistry, Indiana University-Purdue University at Indianapolis, 1125 East 38th Street, Indianapolis, Indiana 46205