Chemical reactions can start and enhanced by sonic waves. Sonochemical reactions by ultrasound are very advanced "green" techniques with exceptional high yields. There are three classes of sonochemical reactions: homogeneous Sonochemistry of liquids, heterogeneous Sonochemistry of liquid-liquid or solid-liquid systems, and, overlapping with the previous techniques, sonocatalysis. The chemical enhancement of reactions by ultrasound has been explored and has beneficial applications in mixed phase synthesis, materials chemistry, and biomedical uses.