SONOCHEMISTRY (APPLICATIONS OF ULTRASOUND IN CHEMICAL SYNTHESIS AND REACTIONS): A REVIEW PART I

Sonochemistry is a powerful and green approach which is being used to accelerate synthesis of organic compounds, and involves the use of ultrasound technique to promote chemical reactions. Ultrasound is the part of the sonic spectrum, which ranges from about 20 KHz to 10 MHz. A large number of organic reactions can be carried out under ultrasonic irradiation in high yields, short reaction times, and mild conditions. Ultrasonic irradiation of liquids causes high energy chemical reactions to occur, often with the emission of light. The origin of sonochemistry and sonoluminescence is acoustic cavitation which is the formation, growth, and implosive collapse of bubbles. The collapse of bubbles caused by cavitation produces intense local heating and high pressures, with very short lifetimes (Hot spots). These hot-spots have an equivalent temperatures of roughly 5,000 K, pressures of about 1,000 atm, and increase reactivity by nearly million-fold using the radical mechanism. A variety of devices have been used for ultrasonic irradiation of solutions.