Effect of Deep Eutectic Solvents on the Heating Profile of Sonicated Organic Solvents

Ultrasound (US) is considered a clean technology, allows less energy expenditure of chemicals and, consequently, less effiuent generation, providing less processing time and reducing the need for heat application in several processes.1 The ultrasound device with probe can emit the irradiation at higher frequencies and direct into the reaction mixture, being, therefore, an effective model for organic synthesis. However, there is still a great need to carry out methodological studies that evaluate the effects of the various reactional parameters related to this equipment. 2 The general objectives of this work are related to the influence of the deep eutectic solvent (DES) on the heating profile of different organic solvents when subjected to ultrasound irradiation. The heating profile of the ultrasonic solvents was determined on a Hielsher UP200Ht apparatus (1.25 mm probe, 90% amplitude). Ultrasonic power (Up) was determined using measurement data of the irradiated solvents, which were run in tubes containing 10 ml each for 15 minutes with and without the addition of DES (1 mmol) as shown in Table 1 (60.12 W), which was almost 3 and 6 times higher than acetonitrile and acetone, respectively. A great increase of Up (about 30%) was observed when DES was added to ethanol, demonstrating the ionic character of this substance. On the other hand, the presence of DES did not significantly alter Up. The data obtained for DES doped ethanol represent the promising environment to explore organic reactions.