|
|Section2= |Section3= |Section4= |Section7= |Section8= }} Butyric acid (from Greek βούτῡρον, meaning "butter"), also known under the systematic name butanoic acid, abbreviated BTA, is a carboxylic acid with the structural formula CH3CH2CH2-COOH. Salts and esters of butyric acid are known as butyrates or butanoates. Butyric acid is found in milk, especially goat, sheep and buffalo milk, butter, parmesan cheese, and as a product of anaerobic fermentation (including in the colon and as body odor). It has an unpleasant smell and acrid taste, with a sweetish aftertaste similar to ether. It can be detected by mammals with good scent detection abilities such as dogs at 10 parts per billion, whereas humans can detect it in concentrations above 10 parts per million. Butyric acid is present in, and is the main distinctive smell of, human vomit.〔 Butyric acid was first observed in impure form in 1814 by the French chemist Michel Eugène Chevreul. By 1818, he had purified it sufficiently to characterize it. Unfortunately, Chevreul did not publish his early research on butyric acid; instead, he deposited his findings in manuscript form with the secretary of the Academy of Sciences in Paris, France. Henri Braconnot, a French chemist, was also researching the composition of butter and was publishing his findings, and this led to disputes about priority. As early as 1815, Chevreul claimed that he had found the substance responsible for the smell of butter.〔Chevreul (1815) ("Lettre de M. Chevreul à MM. les rédacteurs des Annales de chimie" ) (Letter from Mr. Chevreul to the editors of the Annals of Chemistry), ''Annales de chimie'', vol. 94, pages 73–79; in a footnote spanning pages 75–76, he mentions that he had found a substance that is responsible for the smell of butter.〕 By 1817, he published some of his findings regarding the properties of butyric acid.〔Chevreul (1817) ("Extrait d'une lettre de M. Chevreul à MM. les Rédacteurs du Journal de Pharmacie" ) (Extract of a letter from Mr. Chevreul to the editors of the Journal of Pharmacy), ''Journal de Pharmacie et des sciences accessoires'', vol. 3, pages 79–81.〕 However, it was not until 1823 that he presented the properties of butyric acid in detail.〔E. Chevreul, ''Recherches chimiques sur les corps gras d'origine animale'' (researches on fatty substances of animal origin ) (Paris, France: F.G. Levrault, 1823), (pages 115–133 ).〕 The name of butyric acid comes from the Latin word for butter, ''butyrum'' (or ''buturum''), the substance in which butyric acid was first found. ==Chemistry== Butyric acid is a fatty acid occurring in the form of esters in animal fats. The triglyceride of butyric acid makes up 3–4% of butter. When butter goes rancid, butyric acid is liberated from the glyceride by hydrolysis, leading to the unpleasant odor. It is an important member of the fatty acid subgroup called short-chain fatty acids. Butyric acid is a medium-strong acid that reacts with bases and strong oxidants, and attacks many metals.〔(ICSC 1334 – BUTYRIC ACID ). Inchem.org (1998-11-23). Retrieved on 2014-03-31.〕 The acid is an oily, colorless liquid that is easily soluble in water, ethanol, and ether, and can be separated from an aqueous phase by saturation with salts such as calcium chloride. It is oxidized to carbon dioxide and acetic acid using potassium dichromate and sulfuric acid, while alkaline potassium permanganate oxidizes it to carbon dioxide. The calcium salt, Ca(C4H7O2)2·H2O, is less soluble in hot water than in cold. Butyric acid has a structural isomer called isobutyric acid (2-methylpropanoic acid). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「butyric acid」の詳細全文を読む スポンサード リンク
|