Exp 863 Synthesis of Indigo and Vat Dyeing Adapted by Brandon English and others from a micro scale procedure by James R McKee and Murray Zanger J Chem Ed 1991 68 A242 A244 Introduction William Perkin and the Development of the Synthetic Dye Industry William Henry Perkin considered a career as an artist He also thought of following in his brother s footsteps to become an architect as his father wished Either way the organic chemicals industry still would have come into existence Its beginnings probably would have occurred about when they did shortly after the midpoint of the 19th Century The time was ripe after all thanks to recent advances in theoretical knowledge about organic chemistry But Perkin after he was shown some elegant crystals by a friend at an early age became exchanted almost obsessed by chemistry And so it was Perkin in fact who launched the industry The oft told saga of Perkin s remarkable achievement is the first episode in Anthony S Travis The Rainbow Makers The Origins of the Synthetic Dyestuffs Industry in Western Europe Lehigh University Press 1993 That s because the first products of the synthetic organic chemical industry and the brightest achievements of its first half century were textile dyes Perkin had a solid grounding in organic chemistry at least what was known about it then after a couple of years at the Royal College of Chemistry in London There he had learned laboratory technique under August Wilhelm von Hofmann an expatriate German who was probably the best teacher of the subject at that time During Easter vacation in 1856 Perkin then barely 18 decided to experiment in the ill equipped lab at his home He was trying to synthesize quinine a medicinal much in demand by his compatriots traveling on empirebuilding missions to the malaria infested tropics He naively thought that he might form the quinine molecule C20H24O2N2 by oxidizing two molecules of allyltoluidine C10H13N Heating a salt of allyltoluidine with potassium bichromate all he got was a dirty brown sludge Curious nevertheless he repeated the experiment with a simpler base aniline This time the precipitate was black Hoping a few crystals of quinine might lurk in the sludge he extracted it with ethanol The resulting solution was an intense purple What Perkin had done so far was largely a matter of blind luck But then his youthful and opportunistic genius came into play He found that the solution was a good dye One story has it that he noticed a purple stain spread over his white shirt when he accidentally spilled a drop of the extract Perkin abandoned his chemical studies much to Hofmann s displeasure He didn t really know exactly what he had produced but he thought he might be able to sell it to England s prosperous textile industry So he patented his discovery With the financial backing of this father a builder and the able assistance of his older brother he built near London the first plant ever dedicated to making organic chemicals He had to find suppliers or learn to prepare for himself the raw materials such as benzene nitric acid nitrobenzene and aniline needed for his process He had to design and fabricate his own process equipment And he had to market his product to the tradition bound textile mills showing dyers how to use it thus pioneering the concept of technical service By the end of 1857 Perkin s plant was operating Fortunately purple was a shade much in fashion at the time so Perkin s aniline purple which he called Tyrian purple but which soon became popularly known as mauve was a quick commercial success The rest as the saying goes is history That history is the subject of Travis exhaustive and fact filled account of the European synthetic dye industry for its first 40 years from mauve to indigo The success of mauve itself was relatively short lived Perkin s dye in fact was a rather muddy washed out hue in part because it was ma mixture rather than a single chemical entity But other chemists in England and France soon followed down Perkin s path experimenting empirically with aniline to produce more brightly colored dyes such as aniline red magenta aniline blue and aniline violet synthesized first by Hofmann himself German chemists several of whom gained their initial experience with dyes in England also turned their attention to synthetic dyes Aided by rapid growth in understanding the structure of aromatic molecules their experiments became more based on theory Their first big achievement in 1869 was the synthesis of alizarin a brilliant red dye previously obtained from the roots of the madder plant Perkin also found how to make alizarin in fact his company beat the Germans in producing it on an industrial scale thereby briefly reviving his fading commercial fortunes But the German dye producers among them the forerunners of such modern chemical behemoths as BASF Hoechst and Bayer were strongly in the ascendancy Their increasingly astute employment of chemical research culminated with development of an industrial process for synthetic indigo previously available only as a natural product by BASF in 1897 Intensely competitive these German companies soon dominated the market As for Perkin he sold off his company in 1874 it eventually became part of ICI and devoted the rest of his life to chemical research discovering the Perkin reaction for making unsaturated acids and studying the magnetic rotary power of organic compounds Indigo is a blue dye that has been used to dye cloth for thousands of years Its first use was by ancient Egyptians to dye mummy cloths Today it is used mainly in the dyeing of blue jeans Indigo was first artificially synthesized in 1880 by J F W Adolph von Baeyer who won the Nobel Prize in 1905 for his work with organic dyes Although Baeyer s synthesis method does not work well for producing the large amounts of indigo that would be needed for industrial applications it does work well for micro scale production and will be used in this experiment In this experiment indigo will be produced using the Baeyer Drewson reaction This involves reacting onitrobenzaldehyde with acetone under highly basic conditions The series of reactions below outlines the steps that the reactants go through in forming the final product O H O OH O NO 2 N O acetone O OH OH N H N OH O NaOH NO2 o nitrobenzaldehyde OH O O OH H N N H O Indigo Indigo like most commercial dyes is water insoluble This means that the dye will not wash out of clothing in the washing machine