Application of Microwave-assisted Reactions in Step-Growth Polymerization (A Review).
In modern synthetic organic chemistry laboratories protocols for convenient andrapid transformations are highly desired. Microwave activation has received considerable attention in recent years and it is a subject of intense debate in the scientific community. This technique as an alternative to conventional energy sources for introduction of energy into reactions has become a very well-known and practical method in various fields of chemistry. Microwave-assisted organic synthesis is known for the spectacular accelerations produced in many reactions as a consequence of the heating rate, a phenomenon that cannot be easily reproduced by classical heating methods. As a result, higher yields, milder reaction conditions, and shorter reaction times can often be attained. Microwave is now extensively accepted as an efficient and non-ionized electromagnetic energy source in several different fields of polymerization reactions such as step-growth, ring-opening and radical polymerizations. Its specific heating method attracts extensive interest because of rapid volumetric heating, suppressed side reactions, energy saving, direct heating, decreased environmental pollutions, and safe operations. This review introduces the application of microwave irradiation in step-growth polymerization in details up to 2008. In order to demonstrate the effectiveness of microwave-assisted reactions, some comparisons are made with the classical heated polycondensations.