The Mystery of the Victorian Purple

Home , Mauveine, University of Aberdeen

Physical Sciences ︱ Dr John Plater An example of a Victorian mauveine dyed silk dress, Science The mystery of the Museum London. Victorian purple dye Piece of silk dyed by Sir William Henry Perkin in 1860.

William Henry Perkin, a young he Victorian era was one of science Purple became the height of fashion in London chemist, patented a and innovation. Cameras, cars, Paris and London in the late 1850s to synthesis in 1856 for a purple T electricity and evolution were early 1860s, and the frenzy over mauve dye he created by accident heralded in under the reign of Queen became known as ‘mauveine measles’. whilst trying to synthesise Victoria. In the world of Chemistry, Dalton Even Queen Victoria was not exempt quinine, a Victorian anti-malarial. and Faraday were making discoveries from the excitement, appearing in 1862 This discovery brought purple, in atomic theory and electricity. One of at the International Exhibition wearing a colour so expensive it had the most famous chemists of this era a silk dress coloured by mauveine. previously only been afforded was William Henry Perkin. Wife of Napoleon III, Empress by royalty and the church, to Eugenie wore mauveine-dyed dresses the mass-market. But there In 1856, an 18-year-old William Perkin, to state functions. is an unsolved mystery: using Hofmann’s assistant at the Royal College Perkin’s patented method, it of Chemistry, was tasked to create a is impossible to recreate the A MYSTERY chemical synthesis of quinine. Quinine is But within this story there lurks a curious product he made. Dr Plater at the University of Aberdeen has been found in tonic water and used as an anti- mystery. Closer inspection of Perkin’s Perkin’s mauve was used to colour 6d A bottle of original William Henry Perkin (WHP) postage stamps from 1867-1880. investigating, and thinks he may malarial. Perkin made several attempts at synthesis method reveals that he may mauveine from the WHP factory in Greenford. have discovered the true method the synthesis over the Easter vacation in have been hiding something. of synthesising mauveine. his home laboratory, using coal tar as a also have contained two impurities, son, Frederick Mollwo Perkin. The A CLUE: SIX PENCE STAMPS source of aniline. Oxidising the aniline with There are eight bottles of mauvine ortho- and para-toluidine, which have ‘Mollwo’ letter, as it is now known, Museum-stored mauveines match each potassium dichromate gave a black sludge alleged to have been made by Perkin a similar chemical structure to aniline. provides evidence that the museum- other in their compositions, and the which didn’t contain aniline: it contained left in the whole world, spread across stored mauveine samples are from Mollwo letter provides evidence that the something far more exciting. Perkin six museums in four cities: London, Dr Plater’s attempts to make mauveine Perkin’s factory. samples originate from Perkin. However, noticed whilst cleaning out a flask with Manchester, Bradford and New York. from different combinations of aniline the synthesis described by Perkin doesn’t ethanol that a purple solution had formed Museum-stored mauveine was tested and toluidines were always unsuccessful Dr Plater used liquid chromatography- produce mauveine with the correct – an observation which led to Perkin in the 1990s and is rich in two main – he never managed to create a product mass spectrometry (LC-MS) to identify composition. Dr Plater deduces from becoming one of the most celebrated components – the chromophores with only the A and B chromophores. chemists of the Victorian era. of mauveine known as mauveine A Every synthesis created four and mauveine B. chromophores of mauveine. Removing We may never know how he did it – The purple substance – initially named the B2 and C chromophores was also aniline purple – was one of the world’s Dr John Plater at the University of impossible. but with Dr Plater’s research we are first synthetic dyes: mauveine. Mauveine’s Aberdeen repeated Perkin’s synthesis as one step closer to the truth. significance as a dye is its elusive colour. it was written in the original patent, and In the search for more information, Throughout history, purple clothes have here’s where the curiosity begins. The Dr Plater was given access to analyse the chromophores present in these this that Perkin actually used a different been worn almost exclusively by the richest synthesis produces not two chromophores three samples of Perkin’s mauveine. mauveine samples. In LC-MS, liquid synthesis method from the one he said in society due to the expense of creating of mauveine, but four: A, B, B2 and C. These samples were stored in museums: chromatography is used to separate he used. purple dyes. Phoenician dye, known one in Manchester, Bradford, and the compounds by running them along a as ‘Purple of the Ancients’, is a famous Did Perkin miss something out when other in Sudbury, the London borough long column filled with reverse phase A final clue in this mystery comes from six example made from predatory sea snails. he patented his method? Or are the where Perkin built both his family home silica gel. The different chromophores pence stamps. Victorian postage stamps samples in these museums not genuine and his factory. reach the end of the column at different printed using mauveine dyes are available Perkin was encouraged by his family to test Perkin’s mauveine? times. Mass spectrometry can then to purchase online. Dr Plater analysed the purple substance for colouring clothes. These samples have made their way be used to identify the structure of the mauveine in 15 six pence stamps A sample was sent to Messrs Pullar of Perth INVESTIGATING THE SYNTHESIS to museums from William Henry each chromophore from its molecular using LC-MS. Each stamp had a slightly who gave their approval. Finding success, To solve this mystery, Dr Plater began Perkin’s family members and from his mass and the way it fragments. This different composition, generally of all four he quickly patented the method. He set investigating the synthesis of mauveine. factory. One sample is accompanied revealed that the Bradford and Sudbury chromophores. A fluctuating composition up a factory with his brother, funded by Perkin’s starting material was aniline with a letter, addressed to Prof mauveines, like the Manchester of mauveine provides further evidence Dr John Plater’s dye detective work uncovers a long unsolved mystery behind Perkin’s his father. In doing so, he brought purple extracted from coal tar, and later made Henry Armstrong Fellow of the Royal mauveine, are highly rich in mauveine that the method for synthesising mauveine mauveine dye. to the Victorian mass market. commercially from coal-tar, which would Society, from William Henry Perkin’s A and B. changed over time.

www.researchoutreach.org www.researchoutreach.org Behind the Research Dr John Plater

E: [email protected] T: +4401224 272927 W: https://www.abdn.ac.uk/ncs/profiles/m.j.plater

Research Objectives References

Dr Plater’s research at the University of Aberdeen is focused M. J. Plater and A. Raab (2017). Liquid chromatography-mass on organic and biological chemistry. spectrometry (LC-MS) analysis of mauveine from the historical London suburb of Sudbury (WH Perkin’s home and factory) and Bradford AURA Link; J. Chem. Res., 41, 441-447. https:// Detail doi.org/10.3184/174751917X14967701766969 John Plater, BSc DIS PhD DSc FRSC CChem M. J. Plater and A. Raab (2018). Synthesis and analysis by Department of Chemistry, liquid chromatography-mass spectrometry of a mauveine University of Aberdeen, composition similar to museum stored mauveine. J. Chem. Meston Walk, Res., 42, 589-594. https://doi.org/10.3184/17475191 Purple became the height of fashion in Paris and Aberdeen, AB24 3UE 8X15411642455207 London in the late 1850s to early 1860s, and the frenzy over mauve became known as ‘mauveine measles’. Joanne Milne (2016) ‘Accidental chemist’ who brought colour Bio to Victorian society was ‘far ahead of his time’ University of John Plater obtained his BSc in Chemistry from Aberdeen, News, December 122016. https://www.abdn. well enough to understand the need Loughborough University in 1986 and his PhD in ac.uk/news/10231/ A purple residue had formed – an for research and development. heterocyclic synthesis from Imperial College of Science, observation which led to Perkin Technology and Medicine in 1989. He was awarded his Joanna Cummings (2017). Purple’s Reign. The Analytical But there may be another answer DSc from The University of Aberdeen in 2009 where Scientist, January 2017, 10. https://theanalyticalscientist.com/ becoming one of the most celebrated to this question. In a lecture in 1896, he is currently Senior Lecturer. fields-applications/purples-reign Perkin revealed his concerns about Philip Ball (2017). Detective work uncovers Perkin’s deep chemists of the Victorian era. his competition: other manufacturers Collaborators understanding of first synthetic dye.Chemistry World, of mauveine were using copper • Andrea Raab February 2017, 14(2), 44. https://www.chemistryworld. THE TRUE SYNTHESIS used by Perkin. But the ‘N-tert-butyl’ chloride as an oxidising agent in place • William T A Harrison com/news/dye-detective-work-uncovers-perkins-chemistry- Some other research groups have addition to the name of p-toluidine of Perkin’s potassium dichromate. secrets/2500193.article suggested that the synthesis method represents a significant feat in chemistry. Dr Plater has strong evidence now used to make the museum-stored This part of the name represents that Perkin never revealed his true mauveine involved using a starting a ‘protecting group’ added to the method. Perkin may well have done material very high in p-toluidine. para-toluidine, preventing it from this intentionally: as the demand for Personal Response However, Dr Plater has shown that this reacting to form mauvine B2 or C and synthetic dyes grew, Perkin wanted synthesis doesn’t create mauveine acid treatment removes it from the to avoid his competition getting hold You have proposed a synthetic method to make rich in A and B chromophores. In fact, mauveine at the end of the synthesis. of his secrets. mauveine which involves some quite sophisticated this method only produces B2 and C, If Perkin was using this method, chemistry – how likely is it that Perkin was using this method? And do you think we will ever know the truth? the chromophores found in very low then he was performing some truly PIONEERING CHEMIST amounts in the museum bottles. pioneering chemistry. Perkin was the first person to mass I have worked on the synthesis and analysis of Perkins mauveine for a decade with the best modern equipment. produce a synthetic dye, but this Having experienced first hand many times the impossibly Dr Plater has a neat solution to this TRADE SECRETS research uncovers a new aspect to difficult selective precipitation or crystallisation of mauveine puzzle. He has found that replacing the One question remains: why would Perkin’s achievements. Analysis of to give mauveine A and B, or the selective synthesis of p-toluidine in the starting material with Perkin patent one method for making mauveine stored in museums, Victorian mauveine A and B from different compositions of amines, another compound, N-tert-butyl-p- mauveine, but use another? stamps, and Perkin’s original patent I believe that the modified method discussed here was toluidine, forms a product dominated provides evidence that Perkin iterated exploited by Perkin. So far, the tert-butylated mauveines of this modified method are ‘traceless’ and have not appeared by mauveine A and B, matching the An answer may be to do with the yield of and improved his method of making in bottles in bulk or on dresses, but such a find would surely museum samples. Dr Plater’s LC-MS product. Dr Plater notes that mauveine his dye, making him one of the first convince the most sceptical person of the hypothesis. charts of this method show a very good is actually very difficult to make. The chemists to realise the value of research Perhaps the manufacture of Perkin’s Dahlia has left a hint match in chromophore composition. yields are low – about 1 per cent. The and development. Because Perkin about modified mauveines because the extra nitrogen method proposed by Dr Plater increases never revealed his true method, we may substituted group which this contains – methyl or ethyl (or tert-butyl), form a family and were not out of synthetic reach Dr Plater believes that his method is the yield to about five per cent. Perkin never know how he did it – but with Dr in the 1860s. actually more similar than the method discovered this synthesis by accident, Plater’s research we are one step closer in Perkins patent to the method actually but clearly understood the chemistry to the truth.