I would purify by fractional distillation under reduced pressure. Then the imidazoline will crystallize.

Try to add some ether remove ethylendiamine if your compound is not ether soluble. The best would be purify by chromatography. 

Simple way to purify it by solvent extratcion; first make it wter soluble with react of salt and separate it between water and organic solvent so as to get whole volume of liquid product then crytallize it with partial soluble nature of product at room temp but completely at boiling temperature.........and possibilly give pure pruduct 

You may play with solvents: add some ether and if some solid forms, filter it, and add to filtrate some hexane. If solid forms filter it next. but if oil with solid form add some drops of ether to find a point to catch maximum pure solid