Tyrian purple dye

C.J. Cooksey, R.S. Sinclair, Colour variations in Tyrian purple dyeing, Dyes in History and Archaeology, 20, 127 135 (2005). 

From ancient times up to the Middle Ages, Tyrian purple dyeing blossomed in Byzantium. However, at the end of the Fourth Crusade and the conquest of Constantinople in 1204, the production of Tyrian purple for the Byzantine court came to an abrupt end. The new rulers were unable to raise sufficient funds required for the continuation of murex purple production. [31]... 

Halogen-containing compounds are not only produced by man, but also by Nature [1740-1742], A brominated indole derivative - Tyrian purple dye - was isolated from the mollusc Murex brandaris by the Phoenicians. Since that time, more than 1,000 halogenated natural products of various structural types have been isolated from sources such as bacteria, fungi, algae, higher plants, marine molluscs, insects, and mammals [1743], Whereas fluorinated and iodinated species are rather rare, chloro and bromo derivatives are found more often. The former are predominantly... 

As early as 2500 bce m India indigo was used to dye cloth a deep blue The early Phoenicians discovered that a purple dye of great value Tyrian purple could be extracted from a Mediterranean sea snail The beauty of the color and its scarcity made purple the color of royalty The availability of dyestuffs underwent an abrupt change m 1856 when William Henry Perkin an 18 year old student accidentally discovered a simple way to prepare a deep purple dye which he called mauveme from extracts of coal tar This led to a search for other synthetic dyes and forged a permanent link between industry and chemical research... 

Textile dyes were, until the nineteenth century invention of aniline dyes, derived from biological sources plants or animals, eg, insects or, as in the case of the highly prized classical dyestuff Tyrian purple, a shellfish. Some of these natural dyes are so-caUed vat dyes, eg, indigo and Tyrian purple, in which a chemical modification after binding to the fiber results in the intended color. Some others are direct dyes, eg, walnut sheU and safflower, that can be apphed directly to the fiber. The majority, however, are mordant dyes a metal salt precipitated onto the fiber facUitates the binding of the dyestuff Aluminum, iron, and tin salts ate the most common historical mordants. The color of the dyed textile depends on the mordant used for example, cochineal is crimson when mordanted with aluminum, purple with iron, and scarlet with tin (see Dyes AND DYE INTERMEDIATES). 

Another ancient dye is the deep blue indigo [482-89-3], the presence of two bromine atoms at positions gives the dye Tyrian purple [19201 -53-7] once laboriously extracted from certain sea shells and worn by Roman emperors. 

Indigoid dyes represent one of the oldest known classes of dyes. For example, 6,6 -dibromoindigo [19201 -53-7] (44) is Tyrian Purple, the dye made famous by the Romans. Tyrian Purple was so expensive that only the very wealthy were able to afford garments dyed with it. Indeed, the phrase "bom to the purple" is still used today to denote wealth. 

Kermisic Acid. Many accounts claim that kermisic acid [476-35-7] (Cl Natural Red 3 Cl 75460) is the oldest dyestuff ever recorded (23). The name kermes is derived from an Armenian word meaning Httle worm for which the later Latin equivalent was vermiculus, the basis of the Knglish word Vermillion. The dye was obtained from an oriental shield louse, K. ilicis which infest the holm o5kQuercus ilex and the shmb oak. coccifera. The dye produces a brilliant scarlet color with an alum mordant. Although expensive, it was cheaper than its rival Tyrian Purple. It was in great demand until the sixteenth century when it was displaced by carminic acid. 

Tyrian Purple was the most expensive and rare dye of the ancient world principally because only a small amount of dye could be obtained from each moUusk, roughly 0.12 mg (95). It was always considered a color of distinction and restricted to regal and ecclesiastical uses ia the Eastern Roman Empire, the heir to the throne at By2antium bore the proud name Porphjro-Genitur, bom to the purple. The Hebrews used purple ia many decorations of the Tabernacle (23). 

The magnificent purple pigment referred to in the Bible and known to the Romans as Tyrian purple after the Phoenician port of Tyre (Lebanon), was shown by P. Friedlander in 1909 to be 6,6 -dibromoindigo. This precious dye was extracted in the early days from the small purple snail Murex brandaris, as many as 12000 snails being required to prepare 1.5 g of dye. The element itself was isolated by A.-J. Balard in 1826 from the mother liquors remaining after the crystallization of sodium chloride and sulfate from the waters of the Montpellier salt marshes ... 

This noble but naive attempt - bearing in mind that only the molecular formula of C20H24N2O2 was known at the time - was doomed to fail. In subsequent experiments with aniline, which was fortunately contaminated with toluidines, Perkin obtained a purple product in low yield. Perkin was quick to recognize the commercial potential of his findings the natural dye, Tyrian purple, which was extracted from a species of Mediterranean snail, cost more per kilogram than gold in 1856. Within a few years the first commercial plant for the production of mauveine was in operation. 

Vat Dyes. Vat dyes are insoluble in water. Indigo, for example, an ancient blue dye, is probably the best-known example of an ancient vat dye others include woad and Tyrian purple. Since the process of dyeing requires that the dye be in solution, dyeing with a vat dye (or vat dyeing, as the process is known) is possible only after the vat dye has been made soluble by a relatively long and somewhat complicated chemical procedure. The terms vat dye and vat dyeing are probably derived from the large tanks or "vats", in which the process was carried out in ancient times. 

Tyrian purple was derived from the "purple snail," the common name for what, in reality, are several species of mollusks of the genus Murex. Each one of the mollusk species yielded a slightly different variety of purple. In Tyre, where the most prized purple dye was produced, Murex brandaris snails were those most abundant and generally used, while in Sidon, not far to the north of Tyre, an amethyst purple variety of the dye was obtained from... 

Vat dyes (the best known are Tyrian purple, indigo and woad) are insoluble in water. Before dyeing, they must be reduced into water-soluble leucoforms. After impregnation of the textile, dyestuffs are again oxidized into colour forms. As far as their extraction is concerned, aprotic solvents are usually recommended, e.g. pyridine, dimethylformamide or dimethylsulfoxide. 

The Chemistry of Indigo Dyeing.—On account of its insolubility the dye itself cannot be applied directly to the fibre. Yet an indirect process of great antiquity is available, for Tyrian purple has been identified as 6 6 -dibromoindigo 1 by Friedlander. The indigo is made soluble... 

They found eager customers in Egyptians and Etruscans, and later among the Greeks and Romans. Jewish traditions accorded Tyrian purple an important place, and there are several Biblical references to it. The demand for the dye exceeded the supply for centuries, guaranteeing that the price was always high. At times... 

Bromine was used centuries before it was identified. A sea mussel known as the murex secretes a hquid that was made into an expensive dye known as Tyrian purple. However, the dyemakers were unaware that a compound of bromine was the main ingredient of the dye until the 1900s. 

People have long used marine organisms as the source of a limited number of synthetic products used in everyday life. Perhaps the most famous of these organisms has been the mollusk Murex bran-dans, from which a beautiful purple dye can he extracted. The dye is obtained from a small organ of the mollusk (the hypobranchial gland), and its preparation is so expensive that it was traditionally used as a dye only for clothing worn by the nobility. For that reason, the dye was called royal purple or, more commonly, Tyrian purple, after the region from which it is obtained. 

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