Dimethyl 2,2'-azobis(2-methylpropionate) is a nitrile-free, oil-soluble azo polymerization initiator with polymerization activity similar to AIBN. However, it has fewer toxic by-products than AIBN, is safer and can be used as an alternative to AIBN. In addition, the highly volatile decomposition products can be removed during the polymer production process, and the polymer after polymerization is highly transparent, so it is expected to be used in semiconductors and liquid crystal displays(LCDs).
To a 250 mL four-necked flask equipped with a condenser, stirrer, gas guide, and thermometer was added 33.2 g (0.2 mol) of azodiisobutyronitrile hydrazine (HAIBN), followed by 150 mL of CH3OH and stirred to dissolve. Under the cooling of ice water bath, 18.2g (0.260mol) Cl2 was passed, stirred, and after 1h of reaction then 5.9g (0.16mol) HCl was passed, and the mixture was stirred and reacted at 20~25??C for 18h. The solids were filtered out, and then added to 80mL of water to hydrolyze. The reaction mixture was frozen and the precipitated solid was filtered. The resulting solid was recrystallized with methanol water to give 19.6 g of white solid dimethyl azodiisobutyrate in 93.6% yield and 99.3% content, m.p. 28~30??C. IR: (KBr, cm-1) 1740 (C=O); 1H NMR ( CDCI3, ??): 1.49 [s, 12H, -C-CH3], 3.65 [s, 6H, - OCH3].
