Oligomers or polymers which are formed by condensation of monomers can be produced in the thin film evaporator. With reactive distillation the two steps, distillation and chemical reaction are combined in one apparatus. A mixture is going in another state through energy input and one of the reaction products is removed in the same process step. GIG Karasek designs for your reactive distillation, special short path and thin film evaporators. The process is characterized not only by a very good yield but also by short response times and low costs. Therefore it is a very economical process.