[3-(Ethoxycarbonyl)propyl]triphenylphosphonium bromide, also known as ECPPTPBr, is a chemical compound that belongs to the class of phosphonium salts. It is primarily used in various organic synthesis reactions and serves as an important intermediate in the production of pharmaceuticals and other fine chemicals. ECPPTPBr is a white crystalline solid with a molecular formula of C23H24BrO2P. It exhibits good stability and solubility in common organic solvents, making it easy to handle and manipulate in laboratory settings. It is typically prepared by the reaction between, by treatment with hydrobromic acid.