An Operationally Simple and Scalable Approach to Functionalized Ionic Liquids from Phosphonium and N-Heterocyclic Halide Salts

Abstract

An approach toward the synthesis of N-heterocyclic anionic ionic liquids is described. The ionic liquids are readily obtained by the treatment of the sodium salt of the parent N-heterocycle with the halide salt of the desired cation. Good to excellent yields (62–99%) of the corresponding ionic liquids are obtained without the use of excessive materials and time associated with conventional methods for synthesizing heterocyclic based ionic liquids.

Key words

ionic liquids - heterocyclic anions - phosphonium salts - imidazolium salts - triazolium salts

• References and Notes

• 1a Tang S, Baker GA, Zhao H. Chem. Soc. Rev. 2012; 41: 4030
• 1b Buzzeo MC, Evans RG, Compton RG. ChemPhysChem 2004; 5: 1106
• 1c Gordon CM. Appl. Catal., A 2001; 222: 101
• 1d Wasserscheid P, Keim W. Angew. Chem. Int. Ed. 2000; 39: 3772
• 2a Kumar V, Talisman IJ, Bukhari O, Razzaghy J, Malhotra SV. RSC Adv. 2011; 1: 1721
• 2b Bender J, Jepkens D, Hüsken H. Org. Process Res. Dev. 2010; 14: 716
• 2c Yadav GD, Motirale BG. Ind. Eng. Chem. Res. 2008; 47: 9081
• 2d Kim DW, Song CE, Chi DY. J. Org. Chem. 2003; 68: 4281
• 2e Wheeler C, West KN, Liotta CL, Eckert CA. Chem. Commun. 2001; 887
• 3a Garcia S, Lourenco NM. T, Lousa D, Sequeira AF, Mimoso P, Cabral JM. S, Afonso CA. M, Barreiros S. Green Chem. 2004; 6: 466
• 3b Chiappe C, Leandri E, Lucchesi S, Pieraccini D, Hammock BD, Morisseau C. J. Mol. Catal. B: Enzym. 2004; 27: 243
• 3c Persson M, Bornscheuer UT. J. Mol. Catal. B: Enzym. 2003; 22: 21
• 3d Kim K.-W, Song B, Choi M.-Y, Kim M.-J. Org. Lett. 2001; 3: 1507
• 4a Matsumoto M, Inomoto Y, Kondo K. J. Membr. Sci. 2005; 246: 77
• 4b Scovazzo P, Kieft J, Finan DA, Koval C, DuBois D, Noble R. J. Membr. Sci. 2004; 238: 57
• 4c Fortunato R, Afonso CA. M, Reis MA. M, Crespo JG. J. Membr. Sci. 2004; 242: 197
• 4d Branco LC, Crespo JG, Afonso CA. M. Angew. Chem. 2002; 114: 2895
• 5a Arce A, Earle MJ, Rodriguez H, Seddon KR. J. Phys. Chem. B 2007; 111: 4732
• 5b Visser AE, Swatloski RP, Rogers RD. Green Chem. 2000; 2: 1
• 5c Huddleston JG, Rogers RD. Chem. Commun. 1998; 1765
• 6a Rogers RD, Seddon KR. Science 2003; 302: 792
• 6b Baleizao C, Gigante B, Garcia H, Corma A. Green Chem. 2002; 4: 272
• 6c Earle MJ, Seddon KR. Pure Appl. Chem. 2000; 72: 1391
• 7a Gurkan BE, de la Fuente JC, Mindrup EM, Ficke LE, Goodrich BF, Price EA, Schneider WF, Brennecke JF. J. Am. Chem. Soc. 2010; 132: 2116
• 7b Gurkan B, Goodrich BF, Mindrup EM, Ficke LE, Massel M, Seo S, Senftle TP, Wu H, Glaser MF, Shah JK, Maginn EJ, Brennecke JF, Schneider WF. J. Phys. Chem. Lett. 2010; 1: 3494
• 7c Anthony JL, Anderson JL, Maginn EJ, Brennecke JF. J. Phys. Chem. B 2005; 109: 6366
• 8a Bara JE, Gabriel CJ, Lessmann S, Carlisle TK, Finotello A, Gin DL, Noble RD. Ind. Eng. Chem. Res. 2007; 46: 5380
• 8b Bates ED, Mayton RD, Ntai I, Davis JH. J. Am. Chem. Soc. 2002; 124: 926
• 8c Brennecke JF, Maginn EJ. AlChE J. 2001; 47: 2384
• 9a Cadena C, Anthony JL, Shah JK, Morrow TI, Brennecke JF, Maginn EJ. J. Am. Chem. Soc. 2004; 126: 5300
• 9b Anthony JL, Maginn EJ, Brennecke JF. J. Phys. Chem. B 2002; 106: 7315
• 10a Ohno H, Fukumoto K. Acc. Chem. Res. 2007; 40: 1122
• 10b Fukumoto K, Yoshizawa M, Ohno H. J. Am. Chem. Soc. 2005; 127: 2398
• 11a Smiglak M, Hines CC, Wilson TB, Singh S, Vincek AS, Kirichenko K, Katritzky AR, Rogers RD. Chem. Eur. J. 2010; 16: 1572
• 11b Smiglak M, Bridges NJ, Dilip M, Rogers RD. Chem. Eur. J. 2008; 14: 11314
• 11c Katritzky AR, Singh S, Kirichenko K, Smiglak M, Holbrey JD, Reichert WM, Spear SK, Rogers RD. Chem. Eur. J. 2006; 12: 4630
• 12 General Procedures for IL Synthesis Method A: A clean, oven-dried round-bottom flask was charged with NaH (1.0 equiv, 1.0 mmol), flushed with N₂, then suspended in THF (4 mL). A solution of 1 (1 equiv, 1.0 mmol) in THF (1 mL) was added dropwise over 30 min, then stirred until evolution of H₂ ceased. A solution of 2 or 3 (1 equiv, 1.0 mmol) in THF (5 mL) was added and the reaction monitored by ¹H NMR (DMSO-d ₆). The resulting mixture was diluted with H₂O (10 mL) and extracted with EtOAc (3 × 15 mL). The combined organic fractions were concentrated under reduced pressure to afford the desired IL. Method B: A clean, oven-dried round-bottom flask was charged with NaOMe/MeOH (0.4 mL of 3.0 M, 1.2 mmol). A solution of 1i (1.0 equiv, 1.2 mmol) in MeOH (5 mL) was added over 10 min, then stirred at r.t. for 30 min. A solution of 2l (1.0 equiv, 1.2 mmol) in MeOH (5 mL) was added, whereupon NaCl precipitation was observed. Reaction stirred for 12–18 h, monitored by ¹H NMR (DMSO-d ₆). Upon completion, MeOH was removed in vacuo, and EtOAc was added (15 mL). Suspended salt was filtered off using Celite and then rinsed with EtOAc (3 × 15 mL). Filtrate was collected and concentrated in vacuo to afford IL 4l as an orange-yellow oil, 77%. Residual halide content was measured at 5–10% by ion chromatography for each sample. 4l: 1H NMR (400 MHz, DMSO-d6): δ = 7.26 (s, 2H), 4.38–4.37 (d, J = 4 Hz, 2 H), 3.70–3.68 (m, 2 H), 3.48–3.46 (m, 2 H), 3.25 (s, 3 H), 1.87–1.83 (d, J = 16 Hz, 9 H). 13C NMR (100 MHz, DMSO-d6): δ = 129.2, 73.2, 72.1, 71.2, 63.9, 63.2, 58.2, 5.3, 4.8. HRMS (ESI): m/z calcd for the C7H18O2P+: 165.1039; found: 165.1059; m/z calcd for C2H2N3–: 68.0254; found: 68.0232.���
• 13a Bao W, Wang Z, Li Y. J. Org. Chem. 2003; 68: 591
• 13b Huddleston JG, Visser AE, Reichert WM, Willauer HD, Broker GA, Rogers RD. Green Chem. 2001; 3: 156
• 14a Zhao G, Jiang T, Gao H, Han B, Huang J, Sun D. Green Chem. 2004; 6: 75
• 14b Audic N, Clavier H, Mauduit M, Guillemin J.-C. J. Am. Chem. Soc. 2003; 125: 9248
• 14c Xu L, Chen W, Xiao J. Organometallics 2000; 19: 1123
• 15 Tsunashima K, Sugiya M. Electrochem. Commun. 2007; 9: 2353
• 16 Struble JR, Kaeobamrung J, Bode JW. Org. Lett. 2008; 10: 957
• 17 Nahm MR, Linghu X, Potnick JR, Yates CM, White PS, Johnson JS. Angew. Chem. Int. Ed. 2005; 44: 2377