Ultrasound promoted synthesis of arylmethylenemalonitriles catalyzed by melamine

Arylmethylenemalonitriles were synthesized in the presence of melamine through the knoevenagel condensation of aldehydes with malononitrile in ethanol. two strategies such as the conventional stirring and ultrasound-assisted method were performed in this work,and improvements were observed by carrying out the reactions under ultrasound irradiation. the effect of frequency and power of ultrasound on the yields was investigated,and the optimum frequency and power was 45 khz and 240 w,respectively. the knoevenagel reaction was carried out smoothly under the optimum conditions with the yields of 80-99% within short time. the melamine catalyst showed high activity and reusability,and exhibited no substantial loss of activity over up to four reaction cycles. this work demonstrated that short reaction times and high yields of arylmethylenemalonitriles can be obtained with the facile operation in the presence of the low-toxic,cheap and reusable melamine catalyst. � 2016,chemical society of pakistan. all rights reserved.