Synthesis and characterization of maleimide-functionalized polystyrene-SiO2/TiO2 hybrid nanocomposites by sol–gel process
Nanoscale Research Letters 2012, 7:350 doi:10.1186/1556-276X-7-350
Synthesis of N-chloromethyl maleimide
N-chloromethyl maleimide was prepared in two steps[1-4]. In the first step, N-ethylmaleimide was prepared using a suspension of 24.5 g (0.25 mol) of maleimide in 20.3 ml of 37% formalin at 30°C with the addition of 0.75 ml of 5% NaOH over a period of 30 min and allowing it to stand for 3 h and then filtered. The crude product yield of 75%, m.p = 103°C, was recrystallized using ethyl acetate
1 H NMR (CDCl3), δ (ppm) = 3.45 (S, 1 H), 5.09 (S, 2 H), and 6.76 (S, 2 H)
and 13 C NMR, δ (ppm) = 61.11, 134.71, and 70.25 (C = O).
In the second step, phosphorous trichloride of 4.3 g (0.03 mol) was added to the solution of 10 g (0.08 mol) of N-methyl maleimide in 50 ml of acetone in an ice bath. Then, the solution was stirred for 30 min and then concentrated at the aspirator. The resulting partly crystalline residue was precipitated by adding 50 ml of ice-cold water and filtered. The product N-chloromethyl maleimide was recrystallization from benzene-petroleum ether mixture. The sequence of reaction N-chloromethyl maleimide is presented in Figure1
1HNMR (CDCl3) δ (ppm) = 5.32 (S, 2 H), and 6.84 (S, 2 H);
13 C NMR δ (ppm) = 44.28, 135.27, and 168.17 (C = O).
FTIR spectra. (a) N-methylolmaleimide, (b) N-chloromethyl maleimide, and (c) maleimide-functionalized polystyrene.
