Ethyl anthraquinone

Hydrogen peroxide is commercially produced by autooxidation of ethyl anthraquinol in a solvent such as toluene or ethylbenzene. The product ethyl anthraquinone is reduced by hydrogen over supported nickel or platinum catalyst to regenerate hack the starting material, ethyl anthraquinol for a continuous production of H2O2. The reaction steps are ... 

Issaq and McNitt [585] published a computer program for peak recognition on the basis of peak areas. They investigated the reproducibility of the area of some well-separated peaks for three solutes (anthraquinone, methyl anthraquinone and ethyl anthraquinone) in the 10 solvents used for their optimization procedure. The solvents included binary, ternary and quaternary mixtures of water with methanol, acetonitrile and THF. The areas were found to be reproducible within about 2 percent. The wavelength used for the UV detector in this study was not reported. 

FIGURE 7-21. Example of use of gradient to solve the general resolution problem. (1) jS-Quinone. (2) 1,4-Naphthaquinone. (3) Anthraquinone. (4) 2-Methyl anthraquinone. (5) 2-Ethyl anthraquinone. (6) 2-Tert-butylanthraquinone. (a) Isocratic separation. Column Bondapak Cig/Corasil, 2.3 mm ID x 122 cm. Mobile phase methanol/water (50/50 v/v). Pressure 1200 psig. (b) First gradient attempt. Column same as in a. Mobile phase 0-100% methanol in water, (c) Successful gradient separation. Column same as in a. Mobile phase 30-70% methanol in water. 

The effect of temperature, and of temperature and pH on the retention of a selected group of compounds using a beta-cyclodextrin column was studied. The results indicated that a plot of Ink vs. 1/T gave linear relationships for anthraquinone, methyl anthraquinone, ethyl anthraquinone, naphthalene and biphenyl using a mobile phase of methanol/water. However, a non linear relationship was observed for a selected group of dipeptides employing a mobile phase of methanol/ammonium acetate at the following pH s 1, 5.5 and 7. The retention times decreased with an increase in the temperature of the column except that for certain dipeptides the retention times increased. The separation factor (a) values decreased by approximately 10 with increase in column temperature from 25°C to 77°C. 

The 2-ethyl anthraquinone formed during the reaction is reduced back to 2-ethyl anthraquinol by catalytic reduction with hydrogen in the presence of palladium. 

MAJOR USES Used in the manufacture of styrene, synthetic rubber, automotive and aviation fuels and cellulose acetate solvent for alkyd surface coatings, propylene oxide, ethyl anthraquinone, ethylbenzene sulfonic acids, alpha methyl benzene alcohol chemical intermediate for diethylbenzene and acetophenone. 

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

Smits first established experimentally that phase behavior of the type shown in Fig. 8 is possible, with his classic investigation of the system ethyl ether + anthraquinone.76-83 83 84 The temperature and pressure of the principal points of the phase diagram are... 

Anthraquinone glycosides and aglycones can be readily separated on silica layers rising moderately polar developing solvents [41 3]. The best such solvents eonsist of ethyl acetate modified to increase polarity by the addition of alcohols or water for the glycosides or changed to decrease polarity by inclusion of hydrocarbon components. 

Glycosidic anthraquinones may be developed using ethyl acetate-methanol-water systems (100 10 10) with suitable adjustments made for polarity. Similarly, aglycones can be separated using a somewhat less polar solvent such as petroleum ether (40 to 60°C)-ethyl acetate-formic acid (75 25 1). Some chosen retention data may be found in a recent monograph [24]. Pigments may be recovered by extraction of the absorbant with acetone or methanol after removal of the individual zones. 

Anthraquinol + 02 —i> Anthraquinone + H202 The anthraquinone derivative is usually 2-ethyl- or 2-pentyl-anthraquinone. The solvent is usually a mixture of two solvents, one for the quinone and one for the quinol. The... 

In a related series of 1,2,4-trisubstituted anthraquinone compounds, the effectiveness of various polar and nonpolar substituents to improve on the low heat fastness of 2-amino-1,4-dihydroxyanthraquinone (3.184 R = H) was examined (Table 3.50). Short-chain alkyl groups (methyl, ethyl) and even the pyranylmethyl ether are relatively ineffective but hydroxyalkyl, cyclohexyl, benzyl and morpholinylethyl groups show moderate increases. Further improvement is given by phenyl, pyridylmethyl and morpholinylpropyl. Outstandingly effective, however, are the benzothiazolyl, dodecylphenyl and fluoro-methylphenyl groupings. 

The most important method of making hydrogen peroxide is by reduction of anthraquinone to the hydroquinone, followed by reoxidation to anthraquinone by oxygen and formation of the peroxide. R is usually ethyl but /-butyl and jec-amyl have also been used. 

More extensive studies using somewhat higher wavelengths have been reported by Geacintov et al. (111, 112). These authors used phototendering dyestuffs notably the sodium salt of anthracene 2,7 disulfonic acid as the sensitizer in aqueous solution. For grafting to cellulose acetate and ethyl cellulose 2-methyl anthraquinone which is soluble in organic solvents was used. The mechanism proposed was the removal of a... 

This product melts at 15° C., boils at 171° C. at 4 mm. and has a density of 1 4724 at 25° C. Replacement of the sulphide by / j8 -dichlorodiethyl sulphone or sulphoxide yields respectively di-p-ethylselenolethyl sulphone9 S02(CH2.CH2.SeC2H5)2, M.pt. 72 5° C., and the corresponding sulphoxide, SO(CH2.CH2.SeC2H5)2, an oil, decomposing on distillation at 4 mm. Condensation of sodium ethyl selenide with sodium anthraquinone-1-n-butylsulphone-5-sulphonate similarly yields 5-ethylselenol-l-n-butyl-sulphone anihraquinone, which does not melt below 300° C. ... 

The alkylated anthraquinone process accounts for over 95% of the world production of H202, mainly because the it operates under mild conditions and direct contact of 02 and H2 is avoided. In this process, 2-alkylanthraquinone (the alkyl group is typically an ethyl, terf-butyl or amyl group) is dissolved in a mixture of a non-polar solvent (C9-Cn alkylbenzene) and a polar solvent [Trioctyl phosphate (TOP), or tetrabutyl urea (TBU) or diisobutyl carbinol (DIBC)] and then hydrogenated over a precious metal (Pd or Ni) catalyst in a three-phase reactor (trickle bed or slurry bubble column) under mild reaction conditions (<5bar, <80 °C) to generate 2-alkylanthrahydroquinone [1-3, 5], The latter is then auto-oxidized with air in a... 

Anthraquinones. A new regioselective route to highly substituted anthraquinones (4) involves the reaction of diketene in the presence of sodium hydride with ethyl 4-uryl-3-oxobutanoates (1) prepared as shown from arylacetic acids. The products, after mcthylation, are cyclized to anthrones (3), which are oxidized to anthraquinones.1... 

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