Anthraquinone

Abstract

Obtaining anthraquinone by oxidizing anthracene with bichromate and sulfuric acid later became the first commercial method for the manufacture of anthraquinone from anthracene. For many years, anthraquinone provided the dyestuff industry with one of the greatest and most prolific building blocks for the manufacture of valuable dyestuffs noted for their outstanding fastness properties. However, in recent times production has fallen off considerably due to the high cost of manufacturing and the discovery of other classes of dyestuffs with good fastness properties. When sublimed, anthraquinone forms a pale yellow, crystalline material, needlelike in shape. It melts at 286°C and boils at 379–381°C. At much higher temperatures, decomposition occurs. Anthraquinone has only a slight solubility in alcohol or benzene and is best recrystallized from glacial acetic acid or high boiling solvents such as nitrobenzene or dichlorobenzene. It is very soluble in concentrated sulfuric acid. In general, anthraquinone is a relatively inert compound exhibiting stability toward oxidation. Only the reduction products involving the keto groups are of any academic or industrial importance. In the dyestuff industry, anthraquinone still ranks high as an intermediate for the production of dyes and pigments having properties unattainable by any other class of dyes or pigments. At this writing (1993) the only two processes for its production are by the Friedel‐Crafts reaction utilizing benzene, phthalic anhydride, and anhydrous aluminum chloride, and by the vapor‐phase catalytic oxidation of anthracene, the latter being preferred. Anthraquinone is a comparatively safe compound. It is a mild allergen and may cause skin irritation. It presents only a slight fire hazard on exposure to heat. The use of benzene in the Friedel‐Crafts process presents serious safety and health problems. Besides its major use in the manufacture of intermediates for anthraquinone dyes and pigments, anthraquinone is finding increasing interest as a catalyst in wood pulping in polymerization of various materials for plastics, and in the isomerization of vegetable oils.

Autoxidation of aromatics

“…The catalytic vapor-phase autoxidation of anthracene to anthraquinone with yields of 85-90% has been described in patents in the 1930s and has found some industrial applications [2,17]. The vapor-phase oxidation of anthracene with air is the preferred synthesis method to produce 9,10-anthraquinone [32], and > 90% yield is possible. However, the most widespread use of oxidation in relation to anthracene is the use of the autoxidation-and-reduction cycle of 9,10-dihydroxyanthracene and anthraquinone to produce hydrogen peroxide [2], as illustrated by Fig.…”

“…Almost complete conversion of anthracene with high selectivity to 9,10-anthraquinone is possible and 9,10-anthraquinone of 99% purity is industrially produced in this way [32]. Secondary and complete combustion products are also obtained is small amounts.…”

Contamination Is a Frequent Confounding Factor in Toxicology Studies with Anthraquinone and Related Compounds

“…AQ is produced in large quantities by three different production methods in various parts of the world (Cofrancesco 1992). The oxidation of anthracene to yield AQ is practiced primarily in Europe, but is now in declining use.…”

“…Anthraquinone (AQ) (9,10-anthracenedione) and structurally related compounds are important in commerce and many are found as natural plant products. AQ is used as an intermediate in the manufacture of dyes and to enhance the efficiency of the Kraft process for the production of paper, thus reducing the number of trees harvested (Cofrancesco 1992). AQ is the active ingredient in the most effective and nonharmful bird repellent used for keeping birds from airport runways or areas where they would conflict with the human population (Ballinger and Price 1996; Cummings et al 1997; Ballinger, Gilmore, and Price 1998; Dolbeer et al 1998).…”

“…From a toxicological viewpoint, a recurring problem in studies reported earlier is that a formerly common synthetic pathway to produce AQ was from the oxidation of anthracene (AQ-OX). The anthracene used was distilled from coal tar and different lots of derived AQ contained varying amounts of polycyclic aromatic hydrocarbon contaminants, particularly the mutagenic isomers of nitroanthracene (Cofrancesco 1992; Butterworth, Mathre, and Ballinger 2001). In a 2-year study the National Toxicology Program (NTP) reported that anthracene-derived AQ-OX induced a weak to modest increase in tumors in the kidney and bladder of male and female F344/N rats and a modest increase in the livers of male and female B6C3F 1 mice (NTP 2004).…”