Anthraquinone is an aromatic organic compound that occurs naturally in certain plants, fungi and insects. Since it contributes to the coloring pigment of such organisms, the compound is used commercially to manufacture dyes. In powdered form, anthraquinone exhibits a color that ranges from gray to yellow and green. However, it produces a variety of different colored dyes, including alizarin (red), oil blue A and oil blue 35, quinizarine green SS and solvent violet 13.
This compound can also be mechanically produced by oxidizing anthracene with chromic acid, or by reducing benzene and phthalic anhydride. The latter method requires hydration before the mixture can be considered as anthraquinone.
Anthraquinone is known by many other names, such as anthrachinon, dioxoanthracene, and several different trade names, including Hoelite and Corbit. It is a derivative of anthracene, a coal-tar byproduct characterized by a chemical structure consisting of a polycyclic aromatic hydrocarbon and three fused rings of benzene.
There are other commercial applications for anthraquinone in addition to producing dyes. For example, it is used as a catalyst in the production of wood pulp and paper. A derivative called 2-ethylanthraquinone is used to manufacture hydrogen peroxide. Anthraquinone has a long history of use as a bird repellent and is used to deter the presence of geese in particular. This action may be due to the laxative properties that the compound possesses when introduced as treated birdseed or grass. In fact, its presence is what lends laxative qualities to several well-known herbs used to treat constipation, such as senna pods, aloe, rhubarb, buckthorn and cascara sagrada.
There are a number of environmental and health concerns associated with anthraquinone. For one thing, its use as a laxative has been linked to a benign but undesirable condition known as melanosis coli, which is characterized by a discoloration of the colon wall.
Two-year studies conducted by the National Toxicology Program (NTP) using animal models indicate that anthraquinone is a liver carcinogen when ingested. These tests also produced evidence that this compound may cause non-cancerous lesions or tumors to appear on various organs. In addition, research conducted by NTP suggests that it may be an endocrine disruptor. As a result of NTP’s findings, the California Environmental Protection Agency included anthraquinone to its list of established carcinogens.
Anthraquinone also presents certain safety challenges to the manufacturing industry. For instance, the substance is highly combustible and cannot be used near an open flame or extreme heat since the compound produces toxic fumes when burned. It is also recommended that workers handling anthraquinone wear a P1 filter respirator to avoid inhaling inert particles, as well as protective gloves and eyewear. Environmentally, the compound is toxic to fish and does not readily biodegrade.
By Karyn Maier