2-Ethylanthraquinone
Encyclopedia
2-Ethylanthraquinone also called2-Ethyl-9,10-anthraquinone is an aromatic organic compound
with the formula
C16H12O2. The slightly yellow powder is used in the production of hydrogen peroxide
(H2O2).
and ethylbenzene
: C6H4(CO)2O + C6H5CH2CH3 → C6H4C2O2C6H3C2H5 + H2O. Both phthalic anhydride and ethylbenzene are readily available but are mainly used in the large-scale production of plastics.
is produced industrially by the anthraquinone process
which involves using 2-alkyl-9,10-anthraquinones for hydrogenation. Many derivatives of anthraquinone are used but 2-Ethylanthraquinone is common because of its high selectivity. The hydrogenation of the unsubsituted ring can reach 90% selectivity by using 2-ethylanthraquinone. Hydrogenation follows the Riedl-Pfleiderer, or autoxidation
, process:
The hydrogenation of 2-ethylanthrahydroquinone is catalyzed by palladium
metal. During hydrogenation both 2-ethylanthrahydroquinone and tetrahydroanthraquinone are produced. The tetrahydro derivative of 2-alkylanthraquinone is easily hyrdrogenated but is more difficult to oxidize. This has led to a split in production methods, with current research focusing on the effectiveness of the tetrahydro system. The formation of the tetrahyrdo derivative can be suppressed through use of special catalysts, solvents, and conditions.
A working solution must be able to keep the 2-ethylanthraquinone dissolved in the hyrdrogenation, oxidation, and extraction steps. Since hydroquinones dissolve better in polar solvents, and quinones dissolve better in aromatic nonpolar solvents, a solvent mixture must be used. Some suggested mixtures are polyalkylated benzenes and alkyl phosphates or tetraalkyl ureas, trimethylbenzenes and alkylcyclohexanol esters, and methylnaphthalene and nonyl alcohols.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the formula
Formula
In mathematics, a formula is an entity constructed using the symbols and formation rules of a given logical language....
C16H12O2. The slightly yellow powder is used in the production of hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
(H2O2).
Production
2-Ethylanthraquinone is prepared from the reaction of phthalic anhydridePhthalic anhydride
Phthalic anhydride is the organic compound with the formula C6H42O. It is the anhydride of phthalic acid. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2002, approximately 4.6 billion kilograms were...
and ethylbenzene
Ethylbenzene
Ethylbenzene is an organic compound with the formula C6H5CH2CH3. This aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene, which in turn is used for making polystyrene, a common plastic material....
: C6H4(CO)2O + C6H5CH2CH3 → C6H4C2O2C6H3C2H5 + H2O. Both phthalic anhydride and ethylbenzene are readily available but are mainly used in the large-scale production of plastics.
Uses
Hydrogen peroxideHydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
is produced industrially by the anthraquinone process
Anthraquinone process
The anthraquinone process is a process for the production of hydrogen peroxide, which was developed by BASF. The technical production of hydrogen peroxide is based on the reduction of oxygen, as in the direct synthesis from the elements...
which involves using 2-alkyl-9,10-anthraquinones for hydrogenation. Many derivatives of anthraquinone are used but 2-Ethylanthraquinone is common because of its high selectivity. The hydrogenation of the unsubsituted ring can reach 90% selectivity by using 2-ethylanthraquinone. Hydrogenation follows the Riedl-Pfleiderer, or autoxidation
Autoxidation
Autoxidation is any oxidation that occurs in open air or in presence of oxygen and/or UV radiation and forms peroxides and hydroperoxides. A classic example of autoxidation is that of simple ethers like diethyl ether, whose peroxides can be dangerously explosive. It can be considered to be a slow,...
, process:
The hydrogenation of 2-ethylanthrahydroquinone is catalyzed by palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
metal. During hydrogenation both 2-ethylanthrahydroquinone and tetrahydroanthraquinone are produced. The tetrahydro derivative of 2-alkylanthraquinone is easily hyrdrogenated but is more difficult to oxidize. This has led to a split in production methods, with current research focusing on the effectiveness of the tetrahydro system. The formation of the tetrahyrdo derivative can be suppressed through use of special catalysts, solvents, and conditions.
A working solution must be able to keep the 2-ethylanthraquinone dissolved in the hyrdrogenation, oxidation, and extraction steps. Since hydroquinones dissolve better in polar solvents, and quinones dissolve better in aromatic nonpolar solvents, a solvent mixture must be used. Some suggested mixtures are polyalkylated benzenes and alkyl phosphates or tetraalkyl ureas, trimethylbenzenes and alkylcyclohexanol esters, and methylnaphthalene and nonyl alcohols.