A rearrangement reaction is a chemical reaction in which the structural arrangement of a molecule or compound is altered, resulting in the formation of a new substance. Synonyms for rearrangement reactions can include rearrangement, transposition, conversion, reordering, and transformation. These reactions are often used in organic chemistry to create new compounds from existing ones by altering the molecular structure. Some common types of rearrangement reactions include the Claisen rearrangement, Pinacol rearrangement, and the Wagner-Meerwein rearrangement. These reactions play an important role in the development and synthesis of new drugs, materials, and chemical compounds.