Efficient synthesis of 2,2'-bis(2-oxazoline)from dimethyl oxalate
In view of the problems in the synthesis of 2,2'-bis(2-oxazoline)(BOZ),such as high cost of raw materials,long reaction time,low yield and complex purification,BOZ was synthesized from dime-thyl oxalate(DMO)and ethanolamine(MEA)via a three-step method.The optimum conditions were as follows:First,in ethanol,DMO and MEA reacted at molar ratio of 1∶2.6 at 40 ℃ for 20 min to obtain N,N-bis(2-hydroxyethyl)acetamide(BHEOA).Then in toluene,BHEOA and SOCl2 reacted at molar ratio of 1∶3 at 50 to 90 ℃ to obtain N,N-bis(chloroethyl)acetamide(BCEOA).Finally,in ethanol containing water absorbent,BCEOA and NaOH reacted at molar ratio of 1∶2 at reflux temperature for 1 h to obtain BOZ.The yields of the three steps were 98.1％,96.3％and 73.6％respectively.After sec-ondary crystallization of the filtrate in the third step,the yield increased to 85.8％.
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