By using reactive distillation processes, limitations due to reaction equilibria and due to azeotropes can be overcome, resulting in an intensified overall process. We here present work on the optimization of a semi-batch process, the heterogeneously catalyzed esterification of methanol and acetic acid. Two different cost functions, minimal batch time and maximal productivity of the process are compared. Constraints are added to ensure the purity of the product and sufficient conversion of the raw materials. The analysis of the influence of the prescribed conversion rates on the productivity helps to detect the crucial parameters of the optimization problem, giving deeper insight into the process.