Reactive distillation is an attractive alternative to conventional multiunit structures. In the case of irreversible reactions involving several products, reactive distillation may effectively improve the selectivity toward a desired intermediate product. However, multiunit processes for such reactions cannot be simply discounted without a systematic comparison with reactive distillation. This work emphasizes such a comparison using the isobutene dimerization reaction as an example. The multiunit configurations considered include the conventional reaction-separation network with and without recycle and a distillation column coupled with a side reactor. Potential configurations of process alternatives are generated for a wide range of the conversion of isobutene and the alternatives are compared on the basis of the selectivity toward diisobutene achieved and cost incurred for identical isobutene conversion. Results show that, for a given isobutene conversion, the reactive distillation process is capable of providing the maximum selectivity among all the investigated alternatives. However, the conventional processes are competitive when costing is also involved in the evaluation.