An apparatus for simultaneously performing a multiplicity of synthesis reactions is disclosed. The synthesizer includes at least one reaction vessel having an access port and a synthesis compartment adjacent the access port. A closable exit channel with an exit port is adjacent the synthesis compartment. The apparatus also includes a base having a plurality of inlets, each of the inlets configured to receive the exit channel of the reaction vessel. A fluid outlet is present that is in communication with the plurality of inlets. A vacuum pump and vacuum line are connected to the fluid outlet for sucking excess reagents and by-products from the reaction vessel. The apparatus further includes a shaker for shaking the reaction vessel while synthesis is proceeding.