Butter yellow

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Structural formula
Structure of 4- (dimethylamino) azobenzene
General
Surname Butter yellow
other names
  • N , N -Dimethyl-4 - [( E ) -phenyldiazenyl] aniline ( IUPAC )
  • 4- (dimethylamino) azobenzene
  • CI Solvent Yellow 2
  • CI 11020
  • Dimethyl yellow
  • Methyl yellow
Molecular formula C 14 H 15 N 3
Brief description

yellow leaflets

External identifiers / databases
CAS number 60-11-7
EC number 200-455-7
ECHA InfoCard 100,000,414
PubChem 6053
ChemSpider 5829
Wikidata Q416956
properties
Molar mass 225.29 g mol −1
Physical state

firmly

Melting point

111 ° C (decomposition)

pK s value

2.96

solubility
  • almost insoluble in water (0.23 mg l −1 at 25 ° C)
  • soluble in ethanol
safety instructions
GHS labeling of hazardous substances
06 - Toxic or very toxic 08 - Dangerous to health

danger

H and P phrases H: 301-351
P: 281-301 + 310
MAK

not fixed

Toxicological data

200 mg kg −1 ( LD 50 ,  rat ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Butter yellow ( CI Solvent Yellow 2 ) is a yellow azo dye from the application group of solvent dyes .

Manufacturing

They are prepared by diazotization of aniline and subsequent coupling with N , N -dimethylaniline .

Synthesis of butter yellow

use

Butter yellow is used as an indicator in titrations . The color change from red to yellow takes place in the pH range of 2.9-4.0.

Historical

Under the name butter yellow , the dye was used in Germany until approx. 1941 and in Switzerland until approx. 1943 to color butter and margarine yellow, but was banned in 1949 due to its highly carcinogenic effect. At the 55th meeting of the German Society for Internal Medicine, which took place in Wiesbaden in May 1949, Nobel Prize winner Adolf Butenandt publicly warned against its use in food. When Butenandt issued his warning, ten years had passed since the dangerous yellow butter disappeared. In 1939, research had recognized the carcinogenic properties of this azo dye. Thereupon Hans Reiter , the President of the Reich Health Office, initiated the restriction or prohibition of its use in the following years and caused the manufacturing companies to withdraw this and similar dyes. Which was followed immediately, but hardly anyone found out: because by order of the Nazi Reich government at the time, no word was allowed to leak into the public. As early as May 1949, just a few weeks after the Wiesbaden Congress, the Food and Agriculture Administration in Frankfurt issued an order prohibiting the dyeing of dairy products with chemical dyes.

Individual evidence

  1. ↑ Entry on 4- (dimethylamino) azobenzene. In: Römpp Online . Georg Thieme Verlag, accessed on June 20, 2014.
  2. ↑ a b c d e Entry on 4- (dimethylamino) azobenzene in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  3. ↑ a b c Entry on butter yellow in the ChemIDplus database of the United States National Library of Medicine (NLM), accessed on December 11, 2016.
  4. ^ Robert N. Proctor: Blitzkrieg against Cancer - Health and Propaganda in the Third Reich . Klett-Cotta, 2002, ISBN 978-3-608-91031-5 , p. 429 ( limited preview in Google Book search).
  5. ↑ Are we being poisoned? | ZEIT ONLINE: Are we being poisoned? | ZEIT ONLINE , accessed on September 9, 2017
  6. ^ H. Schaefer: Negotiations of the German Society for Surgery . Springer-Verlag, 2013, ISBN 978-3-662-24761-7 , p. 39 ( limited preview in Google Book search).
  7. ↑ A life for biology (history): Festschrift for the 75th birthday of ... Kleine Verlag, 2000, ISBN 978-3-89370-310-4 , p. 195 ( limited preview in Google Book search).

Web links

Commons : Buttergelb  - Collection of images, videos, and audio files