Precipitation is also useful to isolate the products of a reaction during workup. Ideally, the product of the reaction is insoluble in the reaction solvent. Thus, it precipitates as it is formed, preferably forming pure crystals. An example of this would be the synthesis of porphyrins in refluxing propionic acid.
Freebase(0.00 / 0 votes)Rate this definition: Cellophane. Cellophane is a thin, transparent sheet made of regenerated cellulose. Its low permeability to air, oils, greases, bacteria and water makes it useful for food packaging.
Medical Definition of cocaine. : a bitter crystalline alkaloid C17H21NO4 obtained from coca leaves that is used medically especially in the form of its hydrochloride C17H21NO4Â·HCl as a topical anesthetic and illicitly for its euphoric effects and that may result in a compulsive psychological need.