Organic Sonochemistry : elucidation of reaction mechanisms of organic reactions caused by ultrasonic irradiation and their application to organic synthesis
Sonochemistry can be defined as the chemical effect caused by ultrasound in a broad sense, but it is defined as the chemical outcome of acoustic cavitation, evolution and collapse of microbubbles as a result of ultrasonic irradiation. According to the most widely accepted hot spot theory at the present time, the gas phase of the cavity reaches high temperatures (5000 K) and pressures (170 MPa). As the lifetime of this hot spot is very short (10-6 s), the rate of the temperature variation is as rapid as 1010 K s-1. These extreme conditions define the characteristics of the sonochemical reactions.
We reported that ultrasonic irradiation switched the course of the reaction from aromatic electrophilic substitution to aliphatic nucleophilic substitution, or ionic reaction to radical reaction. We coined the term, sonochemical switching.
