A broad range of organic synthesis reactions can be conducted by means of a process using two polymeric supports, each carrying different reactive species. A liquid medium containing a specifically selected intermediate reactant, in a solvent, is circulated between the supports in order to remove the reactive species from the first support by reaction with the intermediate, and permit the reactive species thus removed to react with the reactive species of the second support, at the same time regenerating the original intermediate reactant. This circulation continues until the second support is suitably loaded with the reaction product, at which time the circulation is stopped and the reaction products separated and recovered. The process may be carried out in an automated apparatus in which sensors are placed at the entrance and exit of the column carrying the second polymeric support. The sensors are capable of sensing the relative presence of the intermediate reactant. When the same content of intermediate reactant is sensed at both the entrance and exit of the second column, the circulation will be automatically stopped as this will indicate complete loading of the second column.