The solvent was removed on the rotary evaporator and the residue was

The solvent was removed on the rotary evaporator and

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The solvent was removed on the rotary evaporator and the residue was chromatographed over silica gel using hexane : ethyl acetate (1 : 1) as eluent. 2-Ethyl-3,5-dimethylpyridine (2). Yield 85%. 1 H NMR (CDCl 3 ): d 8.14 (1H, s, 6-H), 7.13 (1H, s, 4-H), 2.70 (2H, q, J = 7.5 Hz, C H 2 CH 3 ), 2.20 (3H, s, Ar-C H 3 ), 2.18 (3H, s, Ar- C H 3 ), 1.20 (3H, t, J = 7.6 Hz, CH 2 C H 3 ). 13 C RMN (CDCl 3 ): d 158.5, 146.8, 138.2, 130.1, 129.9, 28.1, 18.4, 17.7, 12.8. 2-Pentyl-3,5-dimethylpyridine (3). Yield: 84%. 1 H NMR (CDCl 3 ): d 8.20 (1H, s, 6-H), 7.22 (1H, s, 4-H), 2.74 (2H, dd, J 1 = 6.3 Hz, J 2 = 9.6 Hz, 1 ¢ -Pen), 2.28 (3H, s, Ar-CH 3 ), 2.26 (3H, s, Ar-CH 3 ), 1.68 (2H, m, 2 ¢ -Pen), 1.38 (4H, m, 3 ¢ ,4 ¢ -Pen), 0.91 (3H, t, J = 7.0 Hz, 5 ¢ -Pen). 13 C RMN (CDCl 3 ): d 157.8, 146.9, 138.3, 130.1, 130.1, 35.2, 32.0, 28.7, 22.6, 18.6, 17.8, 14.1. Electrospray MS (micrOTOF Focus) m / z (%) 179.2 [(C 12 H 19 N) + 2] + (28), 178.15928 [(C 12 H 20 N) requires 178.15903 (100)]. General procedures for the synthesis of pyridinium halides The 1-alkyl halide (5 equivalents) was added dropwise to a solution of the 2-alkyl-3,5-dimethylpyridine in acetonitrile This journal is © The Royal Society of Chemistry 2011 Green Chem. , 2011, 13 , 2768–2776 | 2773 Published on 18 August 2011. Downloaded by Memorial University of Newfoundland on 12/22/2018 10:10:24 PM. View Article Online
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(5 mL per mmol of starting trialkylpyridine). The reaction mixture was stirred at 80 C until completion. The reaction progress was followed by t.l.c. using silica gel 60 GF-254 aluminum sheets and Cl 2 CH 2 : CH 3 OH (95 : 5) as eluent. The mixture was heated under reduced pressure and the resulting IL was washed with ethyl ether (4 ¥ 3 mL per mmol of starting trialkylpyridine). The remaining ethyl acetate was removed by heating under reduced pressure to afford the desired IL that was dried by heating at (373.15 to 383.15 K) and stirring under high vacuum (2 ¥ 10 - 1 Pa) for 48 h. 1-Hexyl-2,3,5-trimethylpyridinium iodide (4). Yield 99%. 1 H NMR (CDCl 3 ): d 9.18 (1H, s, 6-H), 7.97 (1H, s, 4-H), 4.75 (2H, dd, J 1 = 6.2 Hz, J 2 = 9.8 Hz, NC H 2 ), 2.77 (3H, s, Ar-CH 3 ), 2.53 (3H, s, Ar-CH 3 ), 2.51(3H, s, Ar-CH 3 ), 1.91 (2H, m, NCH 2 C H 2 ) 1.46 (2H, m, N(CH 2 ) 2 C H 2 ) 1.32 (4H, m, N(CH 2 ) 3 C H 2 C H 2 ) 0.86 (3H, t, J = 7.1 Hz, N(CH 2 ) 5 C H 3 ). 13 C NMR (CDCl 3 ): d 150.5, 147.1, 142.8, 138.6, 136.4, 59.7, 31.2, 30.6, 26.2, 22.5, 20.7, 18.5, 17.5, 14.0. Electrospray MS (apex-Qe) m / z (%) 1206 [(C 14 H 24 N) 4 (I) 3 + 1] + (5), 1205 [(C 14 H 24 N) 4 (I) 3 ] + (9), 541 [(C 14 H 24 N) 2 (I) + 2] + (3), 540 [(C 14 H 24 N) 2 (I) + 1] + (26), 539.28492 ([(C 14 H 24 N) 2 (I)] + requires 539.28567, 100), 207 [(C 14 H 24 N) + 1] + (6), 206 [C 14 H 24 N] + (49). 2-Ethyl-1-hexyl-3,5-dimethylpyridinium bromide (5). Yield 98%. 1 H NMR (CDCl 3 ): 1 H NMR (CDCl 3 ): d 9.47 (1H, s, 6-H), 7.99 (1H, s, 4-H), 4.76 (2H, dd, J 1 = 5.7 Hz, J 2 = 10.3 Hz, NCH 2 ), 3.02 (2H, q, J = 7.6 Hz, 2-CH 2 ), 2.51 (3H, s, Ar- CH 3 ), 2.50 (3H, s, Ar-CH 3 ), 1.91 (2H, m, NCH 2 C H 2 ), 1.45 (2H m, N(CH 2 ) 2 C H 2 ), 1.28 (7H, m, N(CH 2 ) 2 C H 2 C H 2 , 2-CH 2 C H 3 ), 0.81 (3H, t, J = 7.0 Hz, N(CH 2 ) 5 C H 3 ). 13 C NMR (CDCl 3 ): d 153.9, 147.2, 144.6, 136.9, 136.6, 57.9, 32.3, 31.2, 26.0, 22.7, 22.3, 19.2, 18.0, 13.9, 12.2. Electrospray MS (micrOTOF Focus) m / z (%) 522 [(C 15 H 26 N) 2 ( 81 Br) + 1] + (11), 521.32829 ([(C 15 H 26 N) 2 ( 81 Br)] + requires 521.32896, 34), 520 [(C 15 H 26 N) 2 ( 79 Br) + 1] + (12), 519.32939 ([(C 15 H 26 N) 2 ( 79 Br)] + requires 519.33084, 28), 221 [(C 15 H 26 N) + 1] + (18), 220 [(C 15 H 26 N)] + (100). 1-Ethyl-3,5-dimethyl-2-pentylpyridinium bromide (6). Yield 92%. 1 H NMR (CDCl 3 ): d 9.63 (1H, s, 6-H), 7.97 (1H, s, 4-H), 4.86 (2H, q, J = 7.27 Hz, NCH 2 ), 2.94 (2H, dd, J 1 = 9.45 Hz, J 1 = 7.11 Hz, 1 ¢ -Pen), 2.52 (3H, s, Ar-CH 3 ), 2.49 (3H, s, Ar-CH 3 ), 1.63 (3H, t, J = 7.3 Hz, NCH 2 C H 3 ), 1.56 (2H, m, 2 ¢ -Pen), 1.44 (2H, m, 3 ¢ -Pen), 1.34 (2H, m, 4 ¢ -Pen), 0.89 (1H, t, J = 7.2 Hz, 5 ¢ -Pen).
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