Synthesis of N′-(3-Chloropropyl)-N′-Methylurea: Methylamine (7.71 g,
1.64 mol) and 3-chloropropyl isocyanate (10.0 g, 1.67 mol) were mixed
in 50 mL dichloromethane at 0 °C and the mixture was stirred for
24 h under nitrogen atmosphere. Then, the solvent was removed
under reduced pressure and the obtained crude product was washed
with ethyl ether for three times at 0 °C. After being dried under
vacuum, solid white product was obtained (≈90% yield).
1 H NMR
(500 MHz, DMSO-d 6 , δ ): 5.99 (s, 1H, CH 3 NH), 5.70 (d, J = 3.5 Hz,
1H, CH 3 NHCONH), 3.62 (t, J = 6.6 Hz, 2H, ClCH 2 ), 3.09
(q, J = 6.4 Hz, 2H, NHCH 2 CH 2 ), 2.53 (d, J = 4.7 Hz, 3H, CH 3 ),
and 1.81 (p, J = 6.6 Hz, 2H, CH 2 CH 2 CH 2
).
Synthesis of Urea-IL: N′-(3-chloropropyl)-N′-methylurea (11.5 g,
1.53 mol) and 1-vinylimidazole (7.9 g, 1.67 mol) were dissolved in 50 mL
acetone. The obtained solution was stirred and refluxed at 70 °C for
24 h. Then, the solvent was removed under reduced pressure and the
obtained crude product was washed with ethyl ether for three times. After
being dried under vacuum at room temperature, the product was further
purified by silica gel column chromatography using trichloromethane/
methane (10:1, v/v) mixture as the eluent to afford the pure product
which is a clear viscous yellow liquid (≈70% yield). 1 H NMR (500 MHz,
D 2 O, δ ): 8.94 (s, 1H, NCHN), 7.72 (d, J = 1.8 Hz, 1H, NCH
CHN), 7.53 (s, 1H, NCHCHN), 7.08 (dd, J = 15.6, 8.7 Hz,
1H, CH 2 CHN), 5.76–5.35 (m, 2H, CH 2 CH), 4.23 (t, J = 6.9 Hz,
2H, NCH 2 CH 2 ), 3.12 (t, J = 6.4 Hz, 2H, CH 2 CH 2 NH), 2.58
(s, 3H, CH 3 ), and 2.05–2.01 (m, 2H, CH 2 CH 2 CH 2
).