As initiator substances are referred to in the chemical to be added to a reaction mixture to facilitate the desired reaction and to start to initiate ie. Similar catalysts initiators are used, if the reaction is not performed or is not taking place to a sufficient extent alone.
In contrast to catalysts initiators are consumed, however, that they take part in the irreversible reaction, and can not be regenerated. In addition, initiators are usually necessary for the formation of reactive intermediates, which actually facilitate the reaction, but then run off alone, while compounds that have reacted with the initiator remain part of the reaction mixture. Catalysts, however, usually lower the activation energies or encourage the availability of the substrate, and thus speed up reactions, but without joining.
Initiators as radical initiators are used extensively in polymer chemistry, in the vulcanization or in nuclear fission reactions. In the plastics industry initiators are of great importance and are often misnamed " accelerator " means. Most precursors of plastic polymers have a certain potential for self-polymerization. In order to avoid that the polymerization takes place before the actual molding, inhibitors are added and the polymerization is started until the desired time by initiators.