Ultrasound mediated synthesis of some pyrazoline derivatives using biocompatible deep eutectic solvent (DES)

In this report an attempt was made to synthesize some pyrazoline derivatives by benzalkonium chloride and urea based deep eutectic (DES) solvent using thermal(NUS) and ultrasonic (US) methods. Similar reaction was tested by conventional solvent (glacial acetic acid) by thermal method. Result obtained in all of the approaches was calculated and compared with regard to the reaction time, temperature and % yield in both of the methods considering the glacial acetic acid and DES as solvent. Reaction took 15 hr to complete when conventional solvent(glacial acetic acid) were used by thermal method, but same reaction finishes in 4hr in thermal and 1hr in ultrasonic method using DES as solvent. Ultrasound assisted synthesis along with DES works under room temperature (RT) irrespective of thermal method where products are formed at much elevated temperature(<800C).Similarly, rise in %yield was observed in DES led reaction either in thermal or ultrasonic method. Interestingly, in DES-ultrasound combined reaction the % yield was as much as 88%. Furthermore, cost effective, recyclable, environmental friendly nature of DES together with ultrasound make ideal for the present research.