Aniline purple dyes

The next milestone in the development of organic synthesis was the preparation of the first synthetic dye, mauveine (aniline purple) by Perkin in 1856 Perkin, 1856, 1862). This is generally regarded as the first industrial organic synthesis. It is also a remarkable example of serendipity. Perkin s goal was the synthesis of the antimalarial drug quinine by oxidation of N-allyl toluidine (Fig. 2.4). 

The foundation of the synthetic dye industry is universally attributed to William Henry Perkin on account of his discovery in 1856 of a purple dye which he originally gave the name Aniline Purple, but which was later to become known as Mauveine. Perkin was a young enthusiastic British organic chemist who was carrying out research aimed not initially at synthetic dyes but rather at developing a synthetic route to quinine, the antimalarial drug. His objective in one particular set of experiments was... 

Aniline is a purple dye that has the distinction of being the first synthetic dye ever made. It was developed in Germany at the end of the 19th century and its manufacture led to the development of the entire synthetic chemical and pharmaceutical industry that we know today. It is used as a dye and also as a stage in the synthesis of other dyes and chemicals. Unfortunately, both aniline and its derivatives, such as monomethyl-analine and dimethylaniline, are toxic. 

Perkins did not obtain the white crystals that characterize quinine, but instead got a reddish-black precipitate. Perkins decided to repeat the experiment replacing allyltoluidine with aniline (CgH NH2). When Perkins oxidized aniline with potassium dichromate (K2Cr2Oy), he got a brown precipitate. Upon rinsing out the container containing this residue, he produced a purple substance that turned out to be the first synthetic dye. Instead of quinine Perkins had produced aniline purple. Perkins decided to leave school and commercialize his discovery. Backed by his father and a brother, Perkins established a dye plant in London and obtained a patent for aniline... 

With the influence of an artist friend interested in painting and dyes, he started to develop aniline purple (Tyrian purple) production, which he patented in 1856 and set up a factory for. The dyestuff industry soon flourished. In 1859, Emanuel Verguin prepared the important dye fuschine, which was subsequently produced in Basel. In 1869, Perkin patented the synthesis of the natural dye alizarin, at the same time as Caro, Lieberman, and Graebe did so in Germany. Later, moreover, Perkin prepared alizarin from anthracene, which had been... 

The father of modem synthetic dyes was William Henry Perkin (1838-1907), who synthesized mauve, or aniline purple, in 1856. The story behind this great story bears telling. William s father was a builder who wanted him to become an architect, but like many others, Perkin did not follow his father s chosen profession. Perkin studied at the City of London School where he became interested in chemistry at the age of 12. A teacher, Mr. Hall, gave him work in the laboratory, which in turn, inspired Perkin to follow his natural curiosity. At age 15, Perkin entered the Royal College of Science and listened to the lectures... 

When Perkin poured an alcohol on the black product, it turned a mauve color. He found a way to extract the purple substance from the black product and determined that his newly discovered substance was perfect for dyeing clothes. He named his accidental discovery aniline purple, but the fashionable people of Paris soon renamed it mauve. 

Through his accidental discovery of aniline purple, William Perkin found an inexpensive way to make the color mauve. His discovery brought on the beginning of the synthetic dye industry. 

This dyestuff comes into commerce as Ethyl Purple, and is prepared by the action of phosgene on diethyl aniline. It dyes bluer shades than Crystal Violet. 

Mauvein is a base whose sulphate, obtained by mixing cold dilute solutions of potassium dichromate and aniline sulpliate, is a fine, purple dye. A blue dye is also obtained by heating mauvein with aniline. 

In the middle of the nineteenth century, the precocious William Henry Perkin (1838-1907) entered the Royal College of Chemistry at the age of 15 and soon became an assistant to its Director, Professor August Wilhelm Hofrnann. " By that time, coal tar had become an unwanted waste product and while commercial benzene and toluene had been obtained from coal tar by distillation, it was still considered a massive nuisance. Working in his home laboratory in London in 1856, young Perkin tried unsuccessfully to synthesize the dmg quinine but obtained instead dark tars. A modification, using the coal-tar component aniline, provided another dark substance that was found, again quite by accident, to be an excellent purple dye, that Perkin named mauve. Perkin left the university, much to Hoffmann s dismay, and built a factory to manufacture mauve financed by his father. Suddenly, a synthetic dye industry emerged and coal tar became a commodity rather than a waste product. 

Show how oxidation of aniline by a sequence related to Eq. (1) might lead to the brilliant red-purple dye "pseudomauveine," which has a structure related to Aniline Black. 

In 1856 eighteen year old William Henry Perkin accidentally discovered mauveine, the first synthetic dye. He was attempting to synthesize quinine (which was used in the treatment of malaria) from aniline and, instead, produced a purple dye. The following year, Perkin opened a factory in Middlesex to produce the synthetic dye in large quantities. 

Wilham Henry Perkin was an entrepreneur and a self-made millionaire at an early age, long before the era of personal computers and dot-coms. His serendipitous synthesis of the purple dye mauve (also known as mauveine or aniline purple) in 1856 brought brightly colored clothing to the masses and laid the foundation for today s chemical and pharmaceutical industries. 

Perkin suspected he had a dye. He left school and used family money to start a factory. Within six months, he was producing what he called Aniline Purple. French dyers clamored for the new dye and named the color mauve. So popular did the color become that this period of history is known as the Mauve Decade. Perkin, having founded the huge synthetic dye industry, could retire, wealthy, at thirty-five. 

Of the triphenylmethane derivatives, gentian violet has been most often used in medical applications. It is a purple dye, so-called because its color resembles that of the gentian flower it has nothing to do with Gentiana species. It is a mixture of crystal violet (hexamethyl-para-rosaniline) 96% and methyl violet (tetramethyl- and pentamethyl-para-rosaniline). Methyl violet was first synthesized by Lauth in 1861 [15 ] after Perkins discovery of aniline dyes [16 ]. 

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). 

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. 

The main objection to most of the published methods is the fact that the authors leave it to be inferred that this is a smooth reaction. None of them points out the fact that an important side-reaction consists in the oxidizing action of arsenic acid upon aniline, with the production of a deeply purple-colored dye as well as much tarry material and some diaryl arsenic acid. 

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