Abstract: The invention relates to a process, more especially a discontinuous process, for conducting a reaction taking place at elevated temperature in which heat-sensitive products are formed. To increase the volume-time yield, a heat transfer unit independent of the reactor is used for heating. The invention also relates to an apparatus for the production of heat-sensitive products at elevated temperatures. This apparatus comprises a reactor and a heating system. To increase the volume-time yield, the heating system comprises at least one heat transfer unit arranged outside and connected to the reactor.