An apparatus for large batch chemical reactions using microwave energy includes a chamber defined by an outer wall, and a vessel disposed inside the chamber, the vessel defined by an inner wall, the inner wall being separated from the outer wall by a gap. The vessel is configured to receive and hold a load. The apparatus further includes a first applicator and a second applicator configured to emit the microwave energy at the load, wherein points at which microwave energy emitted by the first applicator and the second applicator enter the load are spaced at a distance from each other that is longer than a penetration depth of the microwave energy into the load such that no electromagnetic intercoupling occurs between the first applicator and the second applicator upon emission of the microwave energy.