Two new compounds have been identified in an original sample of mauveine dye that was made by Sir William Perkin over 150 years ago. 

Mauveine, with its characteristic purple colour, was the first synthetic dye molecule, and its production is thought by many to mark the beginning of the modern organic chemical industry.

Now, a team of researchers led by João Seixas de Melo at the University of Coimbra and Maria João Melo at the New University of Lisbon, both in Portugal, have discovered two new compounds during their analysis of a historic sample of the dye from the Science Museum in London.¹

Mauveine dye was already known to contain mauveine A (with two methyl groups) and mauveine B (with three methyl groups).² The components discovered by Seixas de Melo and colleagues are mauveine B2, a structural isomer of mauveine B, which differs in the location of a methyl group, and a structure with four methyl groups, called mauveine C.

Tony Travis, an expert in the history of chemistry and technology at the Hebrew University of Jerusalem, Israel, welcomed the findings. 'Perkin thought that the commercial mauve dye consisted of more than one component,' said Travis. 'This work shows that even though Perkin was unable to establish the structures of these components, he was correct in his findings.'

Using the same starting materials and procedure as Perkin, Seixas de Melo's team made a fresh mauveine sample and compared its composition with that of the historical sample. The different molecular components were separated using high performance liquid chromatography. The chromatograms showed that mauveine B2 and mauveine C, were present in both samples.

Seixas de Melo believes the identities of these mauveine constituents have only now been uncovered as a result of the more efficient chromatographic techniques that are currently available.

'Perkin would be delighted... he spent years trying to establish the constitution and structure of the mauve dye both as a scientific puzzle and because he believed that the constitution would suggest how new derivatives might be made,' said Travis. 'These newly available structures suggest why Perkin failed to prepare a series of derivatives, as had been the case for aniline red.'

Seixas de Melo hopes to extend the study to look at other ancient dyes including indigo and dracoflavylium, which is a major constituent of the bright red resin known as dragon's blood.

Alison Stoddart