|
|Section2= |Section3= |Section6= |Section7= |Section8= }} Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. Its chemical structure, shown in the table at right, features two hydroxyl groups bonded to a benzene ring in a ''para'' position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843.〔F. Wöhler (1844) "Untersuchungen über das Chinon" (Investigations of quinone), ''Annalen der Chemie und Pharmacie'', 51 : 145-163. (From page 146: ) ''"Das so erhaltene Destillat … enthält … einen neuen, krystallisierenden Körper, den ich unter dem Namen ''farbloses Hydrochinon'' weiter unten näher beschreiben werde."'' (The distillate so obtained … contains … a new, crystallizable substance, that I will describe, under the name of ''colorless hydroquinone'', further below in more detail.) ( Wöhler's empirical formula for hydroquinone (p. 152) is incorrect because (1) he attributed 25 (instead of 24) carbon atoms to the molecule, and (2) as many chemists at the time did, he used the wrong atomic masses for carbon (6 instead of 12) and oxygen (8 instead of 16). With these corrections, his empirical formula becomes: C12H12O4. Dividing the subscripts by 2, the result is: C6H6O2 , which is correct. )〕 ==Production== Hydroquinone is produced industrially by two main routes.〔Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. .〕 * The most widely used route is similar to the cumene process in reaction mechanism and involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene. This compound reacts with air to afford the bis(hydroperoxide), which is structurally similar to cumene hydroperoxide and rearranges to give acetone and hydroquinone in acid. * A second route involves hydroxylation of phenol. The conversion uses hydrogen peroxide and affords a mixture of hydroquinone and catechol: :C6H5OH + H2O2 → C6H4(OH)2 + H2O Other, less common methods include: * The oxidation of aniline by manganese dioxide followed by reduction of the resulting 1,4-benzoquinone. The process is conducted batchwise and generates a substantial waste stream. * A potentially significant of synthesis of hydroquinone from acetylene and iron pentacarbonyl has been proposed Iron pentacarbonyl serves as a catalyst, rather than as a reagent, in the presence of free carbon monoxide gas. Rhodium or ruthenium can substitute for iron as the catalyst with favorable chemical yields but are not typically used due to their cost of recovery from the reaction mixture.〔 * Hydroquinone and its derivatives can also be prepared by oxidation of various phenols. Examples include Elbs persulfate oxidation and Dakin oxidation: * Hydroquinone was first obtained in 1820 by the French chemists Pelletier and Caventou via the dry distillation of quinic acid.〔See: * Pelletier and Caventou (1820) "Recherches chimiques sur les quinquinas" (Chemical investigations of quinquinas (the bark of various Cinchona trees )), ''Annales de Chimie et de Physique'', 2nd series, 15 : 289-318, 337-364. (On pages 341-342 ), the preparation and properties of ''l'acide pyro-kinique'' (pyroquinic acid or hydroquinone) are discussed. * 〕 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「hydroquinone」の詳細全文を読む スポンサード リンク
|