The sophisticated chemistry behind a simple – yet infectiously popular – purple dye
Joanna Cummings |
It all started with a vivid purple dye, discovered during the quest for anti-malaria treatments in the 1850s. William Henry Perkin was attempting to develop a synthetic form of quinine when he stumbled upon the formula for a purple dye, which he promptly patented as ‘mauveine’ in 1856.
During this period of the Victorian era, the demand for synthetic dyes was growing at a rapid rate, and the expensive method for producing mauveine gave it an extra air of exclusivity. The rapid growth in the dye’s popularity led to it being dubbed ‘mauveine measles’, and even royalty got the bug – Queen Victoria and Empress Eugenie, wife of Napoleon III each wore mauveine-dyed dresses to state functions. As a result, competition to produce the dye was tough.
Now, researchers at Aberdeen University have discovered that in an attempt to fool his competitors and hide the true formulation, Perkin may have made several permutations of the dye – suggesting he had a more sophisticated approach than previously thought.
John Plater’s team used LC-MS to analyze 15 six pence stamps produced with mauveine between 1865 and 1869, and compared this with Perkin’s mauveine (obtained from the Manchester Museum of Science and Industry). They discovered striking chemical differences between the two (1). “The museum-stored mauveine, which is only available in four sites around the world, has two key ingredients, but the mauveine used on the majority of stamps analyzed has a very different composition to Perkin’s mauveine and a different method of synthesis seems reasonable,” Plater says. “This suggests that the samples given to the museums are true to the method used to manufacture the mauveine commercially, but are not the same as the mauveine made by his patented method.”
Plater believes Perkin never fully revealed what he did to scale up production of his famous dye. “Mauveine is a very difficult thing to make because the yield is very low. The yields I have been able to reproduce in a lab give around five percent rather than the one percent from his patented method of 1856 [...] On this basis, it is clear to see why a more efficient method was needed for mass manufacturing,” Plater says. “I propose that he used a very early form of traceless synthesis to modify the composition and improve the yield. And that indicates that far from being an ‘accidental’ chemist, he really was a true pioneer of his time.”
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- MJ Plater, A Rabb, “Mauveine and the mauve shade six pence stamp”, J Chem Res, 40, 648-651 (2016).