Ultrasound and microwave irradiation: contributions of alternative physicochemical activation methods to Green Chemistry

This perspective article reviews the evolution of research practices and challenges reported in the literature for the use of ultrasound (US) and microwave (MW) in greener chemical processes. Based on the articles published in the Green Chemistry journal from 1999 to now, deemed as a mirror of the evolution of these technologies in eco-compatible applications, this article identifies the main thrust of research involving US and MW. Future deliberations involving these technologies by themselves or in combination including the current and anticipated challenges are highlighted.