Microwave reactions in silicon carbide vials - which are heated by microwaves but shield the contents from radiation - have confirmed that most of the benefits seen in microwave-assisted chemistry are purely due to heating, Austrian chemists say.1 Oliver Kappe and his group, from the University of Graz, used custom-made sintered silicon carbide (SiC) reaction vessels to separate the heating effects of microwave radiation from so-called 'non-thermal' or 'specific' microwave effects, whereby enhancements in reaction rate, yield or selectivity are attributed to some direct interaction of the reaction mixture with the microwave radiation. Silicon carbide is ideal for this purpose because it completely absorbs...