Введение
Органические соединения
Xylenols are organic compounds with the formula (CH3)2C6H3OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with two methyl groups at various positions relative to the hydroxyl group. Six isomers exist, of which 2,6 xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. The name xylenol is a portmanteau of the words xylene and phenol. 2,4 Dimethylphenol together with other xylenols and many other compounds are traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. These residue contains a few percent by weight of xylenols as well as cresols and phenol. The main xylenols in such tar are the 3,5 , 2,4, and 2,3 isomers. 2,6 Xylenol is produced by methylation of phenol using methanol in the presence of metal oxide catalysts:
C6H5OH + 2 CH3OH → (CH3)2C6H3OH + 2 H2O
Typically, xylenols also ethylphenols, which have very similar physical properties.
Ксиленолы – это органические соединения с формулой (CH3)2C6H3OH. Они представляют собой летучие бесцветные твердые вещества или маслянистые жидкости. Это производные фенола с двумя метильными группами, расположенными в различных позициях относительно гидроксильной группы. Существует шесть изомеров, среди которых 2,6-ксиленол, с обеими метильными группами в орто-положении к гидроксильной группе, является наиболее важным. Название «ксиленол» является смешением слов «ксилен» и «фенол». 2,4-диметилфенол, наряду с другими ксиленолами и многими другими соединениями, традиционно извлекается из каменноугольной смолы – летучих веществ, получаемых при производстве кокса из угля. Эти остатки содержат несколько процентов по массе ксиленолов, а также крезолов и фенола. Основными ксиленолами в такой смоле являются 3,5-, 2,4- и 2,3-изомеры. 2,6-ксиленол получают путем метилирования фенола метанолом в присутствии катализаторов на основе оксидов металлов:
Xylenols are organic compounds with the formula (CH3)2C6H3OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with two methyl groups at various positions relative to the hydroxyl group. Six isomers exist, of which 2,6 xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. The name xylenol is a portmanteau of the words xylene and phenol. 2,4 Dimethylphenol together with other xylenols and many other compounds are traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. These residue contains a few percent by weight of xylenols as well as cresols and phenol. The main xylenols in such tar are the 3,5 , 2,4, and 2,3 isomers. 2,6 Xylenol is produced by methylation of phenol using methanol in the presence of metal oxide catalysts:
C6H5OH + 2 CH3OH → (CH3)2C6H3OH + 2 H2O
Typically, xylenols also ethylphenols, which have very similar physical properties.
C6H5OH + 2 CH3OH → (CH3)2C6H3OH + 2 H2O
Xylenols are organic compounds with the formula (CH3)2C6H3OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with two methyl groups at various positions relative to the hydroxyl group. Six isomers exist, of which 2,6 xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. The name xylenol is a portmanteau of the words xylene and phenol. 2,4 Dimethylphenol together with other xylenols and many other compounds are traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. These residue contains a few percent by weight of xylenols as well as cresols and phenol. The main xylenols in such tar are the 3,5 , 2,4, and 2,3 isomers. 2,6 Xylenol is produced by methylation of phenol using methanol in the presence of metal oxide catalysts:
C6H5OH + 2 CH3OH → (CH3)2C6H3OH + 2 H2O
Typically, xylenols also ethylphenols, which have very similar physical properties.
Как правило, вместе с ксиленолами присутствуют также этилфенолы, обладающие очень схожими физическими свойствами.
Xylenols are organic compounds with the formula (CH3)2C6H3OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with two methyl groups at various positions relative to the hydroxyl group. Six isomers exist, of which 2,6 xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. The name xylenol is a portmanteau of the words xylene and phenol. 2,4 Dimethylphenol together with other xylenols and many other compounds are traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. These residue contains a few percent by weight of xylenols as well as cresols and phenol. The main xylenols in such tar are the 3,5 , 2,4, and 2,3 isomers. 2,6 Xylenol is produced by methylation of phenol using methanol in the presence of metal oxide catalysts:
C6H5OH + 2 CH3OH → (CH3)2C6H3OH + 2 H2O
Typically, xylenols also ethylphenols, which have very similar physical properties.
Свойства
Физические свойства шести изомерных ксиленолов схожи. Изомер 2,6-ксиленол, 2,5-ксиленол, 2,4-ксиленол, 2,3-ксиленол, 3,4-ксиленол, 3,5-ксиленол.
Структура CAS 576-26-1 95-87-4 105-67-9 526-75-0 95-65-8 108-68-9
Tпл °C 43 45 63 65 22 23 70 73 62 68 61 64
Tкип °C 203 212 211 212 217 227 222
pKa 10.59 10.22 10.45 10.50 10.32 10.15
Плотность г/мл 0.971 1.011
Применение
Вместе с крезолами и крезиловой кислотой, ксиленолы представляют собой важный класс фенолов, имеющих большое промышленное значение. Они используются в производстве антиоксидантов. Ксиленоловый оранжевый – это окислительно-восстановительный индикатор, основанный на ксиленольном скелете. 2,6-Ксиленол является мономером для поли(p-фениленоксида) (PEO) – инженерных смол, получаемых путем окислительного сочетания углерода и кислорода.