A critical assessment of the greenness and energy efficiency of microwave-assisted organic synthesis

The question "why should microwave chemistry be green?" is evaluated in the context of the twelve principles of green chemistry, with a focus on the 6th principle: design for energy efficiency. A significant number of publications on microwave-assisted organic transformations during the past 25 years describe this non-classical heating technology as being "green", assuming that microwave dielectric heating is more energy efficient than classical conductive heat transfer methods. In this Perspective article, we critically assess the energy efficiency of microwave-assisted transformations in the context of scaling-up this technology to production quantities.