Azuline

Type of dye

Not to be confused with Azulene.

Azuline is a coal-tar blue dye that became popular for colouring silk in 1861. It was one of the first synthetic dyes.[1] The name was a combination of "azure" and "aniline". A variant of the name was "Azurine". The word was introduced as a colour term about the same time as "mauve" and "magenta", but it has not survived in the English language.[2]

The dye is made from phenol, first oxidising it with oxalic acid and sulfuric acid to make a red substance called rosolic acid. By treating this with ammonia, a dye called red coralline or péonine was made. When reacted with aniline, the blue azuline was produced. This was invented by Jules Persoz in Paris. A company in Lyon called Guinon, Marnas & Bonnet bought the process and established a patent.[3] In 1862 azuline was selling for 450 francs per kilogram.[4]

Chemists at first did not know the structure of the molecules in the coal tar dyes including azuline.[5]

Use of azuline was superseded by aniline blue.[6]

## Properties[edit]

As a solid, azuline has a metallic appearance with a copper red colour. It hardly dissolves in water, but does dissolve in alcohol. In alcohol it has a strong blue colour, but still has a red tinge.[7] The dye is colourfast, resisting fading by light.[5] Sulfuric acid solution gives a red solution. Iodine destroys the substance. Ammonium sulfide reduces the colour to pale yellowish-brown.[8]

## References[edit]

1. ^ "The New Blue Dye "Azuline"". The Chemical News. 3 (73): 255. 27 April 1861.
2. ^ Blaszczyk, Regina Lee; Spiekermann, Uwe (2017). Bright Modernity: Color, Commerce, and Consumer Culture. Springer. ISBN 9783319507453.
3. ^ Gaudillière, J. (1998). The Invisible Industrialist: Manufacture and the Construction of Scientific Knowledge. Springer. pp. 128–129. ISBN 9781349264438.
4. ^ Morris, Peter J.T.; Travis, Anthony S. (November 1992). "A History of the International Dyestuff Industry". Archived from the original on August 25, 2006. Retrieved 30 January 2018.`{{cite web}}`: CS1 maint: unfit URL (link) Originally in American Dyestuff Reporter vol 81 no 11
5. ^ a b Reinhardt, Carsten; Travis, Anthony S. (2013). Heinrich Caro and the Creation of Modern Chemical Industry. Springer Science & Business Media. p. 116\. ISBN 9789401593533.
6. ^ REIMANN, M. (1868). ANILINE AND ITS DERIVATIVES. J. Wiley and son. p. 148.
7. ^ "Dye-stuffs" (PDF). Retrieved 30 January 2018.
8. ^ Perkin, W. H. (1862). "XIX. On colouring matters derived from coal tar". Quarterly Journal of the Chemical Society of London. 14 (1): 230. doi:10.1039/qj8621400230.