Pittakall

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Structural formula
Structure of hexamethoxyparafuchsin
General
Surname Pittakall
other names
  • Hexamethoxyparafuchsin
  • Hexamethoxyparosaniline
Molecular formula C 25 H 29 N 3 O 6
Brief description

blue solid

External identifiers / databases
CAS number 47743-62-4
Wikidata Q7199099
properties
Molar mass 467.51 g mol −1
Physical state

firmly

safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pittakall is the first synthetically produced dye . It was discovered by chance in 1832 by the German chemist Karl von Reichenbach , who is also considered the discoverer of kerosene , phenol , eupion , paraffin wax and creosote .

discovery

In the 1830s, Karl Reichenbach researched the components of beech tar . Together with Hugo Karl Eduard zu Salm-Reifferscheidt, Reichenbach was co - owner of iron and steel works in Blansko in Moravia . Reichenbach used the creosote from the coal piles there to paint the wooden fence around his property, in the hope that the penetrating smell of the creosote would prevent dogs from urinating on the fence. Creosote contains a number of polycyclic aromatic hydrocarbons , simple aromatics as well as tar acids , tar bases and other ingredients.

The dogs were not prevented from urinating, but the creosote reacted with the dog's urine to form a blue dye. Reichenbach called this Pittakall, from the Greek words πίττα ( pítta , "bad luck", "resin") and κάλλος ( kállos , "beauty"). He later succeeded in producing pure Pittakall as a blue solid by reacting beech pitch with barium oxide . Pittakall is insoluble in water, ethanol and diethyl ether , but soluble in acids. The pure substance consists of orange needles that dissolve blue in the alkaline. Pittakall was used as a blue textile dye that can be deposited on textiles stained with aluminum oxide . The blue dye is light and water resistant.

The oxidation of Pittakall produces eupittonic acid , a yellow, crystalline substance. Pittakall has had little commercial success, however.

Structure elucidation

The constitution clarification of Pittakall took place in 1878 by August Wilhelm von Hofmann . Hofmann was able to show that the reaction of 2,6-dimethoxyphenol (pyrogallic acid dimethyl ether ) 1 with 4-methyl-2,6-dimethoxybenzene (methyl pyrogallic acid dimethyl ether ) 2 forms eupittonic acid 3 . This implementation is analogous to the representation of parafuchsin from aniline and p -toluidine . The reaction of eupittonic acid with ammonia results in the blue pigment Pittakall 4 :

Synthesis of Pittakall (Hexamethoxypararosaniline / Hexamethoxyparafuchsin)

Synthesis of Pittakall (Hexamethoxyparafuchsin)

Individual evidence

  1. ^ A b c George B. Kauffman: Pittacal - The first synthetic dyestuff. In: Journal of Chemical Education. 54, 1977, p. 753, doi: 10.1021 / ed054p753 .
  2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  3. ↑ Matthijs de Keijzer, Maarten R. van Bommel, Regina Hofmann-de Keijzer, Regina Knaller, Edith Oberhumer: Indigo carmine: Understanding a problematic blue dye. In: Studies in Conservation. 57, 2013, pp. S87-S95, doi: 10.1179 / 2047058412Y.0000000058 .
  4. ↑ Jöns Jacob Berzelius: Textbook of Chemistry: 8th volume . Arnoldsche Buchhandlung, Dresden, Leipzig, 1838, p. 578.
  5. ↑ AW Hofmann: Subsequent notes on Pittakall and Eupittonic acid. In: Reports of the German Chemical Society. 12, 1879, pp. 2216-2222, doi: 10.1002 / cber.187901202262 .
  6. ↑ Carl Graebe: History of Organic Chemistry . First volume. Julius Springer, Berlin 1920, p. 359 ( digitized version ).
  7. ↑ Franz Ferzak: Baron Karl von Reichenbach . FFWASP EBOOKS, 2017 ( limited preview in Google Book Search).