12-1+Acetic+Acid





Vinegar was known early in civilization as the natural result of air exposure of beer and wine, as acetic acid-producing bacteria are present globally. The use of acetic acid in alchemy extends into the third century BC, when the Greek philosopher Theophratus described how vinegar acted on metals to produce pigments useful in art, including white lead (lead carbonate) and verdigris, a green mixture of copper salts including copper (II) acetate. Ancient romance boiled soured wine in lead pots to produce a highly sweet syrup called sapa. Sapa was rich in lead acetate, a sweet substance also called sugar of lead or sugar of Saturn, which contributed to lead poisoning among the Roman aristocracy. In the 8th century, Jabir Ibn Hayyan was the first to concentrate acetic acid from vinegar through distillation. In the Renaissance, glacial acetic acid was prepared through the dry distillation of certain metal acetates (the most noticeable one being copper(II) acetate). The 16th-century German alchemist Andreas Libavius described such a procedure, and he compared the glacial acetic acid produced by this means to vinegar. The presence of water in vinegar has such a profound effect on acetic acid's properties that for centuries chemists believed that glacial acetic acid and the acid found in vinegar were two different substances. French chemist Pierre Adet proved them to be identical chlorination of carbon disulfide to carbon tetrachloride, followed by pyrolisis to tetrachloroethylene and aqueous chlorination to tricholoroacetic, and concluded with electrolytic reduction to acetic acid. By 1910, most glacial acetic acid was obtained from the "pyroligneous liquor" from distillation of wood. The acetic acid was isolated from this by treatment with milk of lime, and the resultant calcium acetate was then acidified with sulfuric acid to recover acetic acid. At that time, Germany was producing 10,000 tons of glacial acetic acid, around 30% of which was used for the manufacture of indigo dyes.