Methyl yellow

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title: "Methyl yellow" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["ph-indicators", "azo-dyes", "anilines", "iarc-group-2b-carcinogens", "dimethylamino-compounds"] topic_path: "general/ph-indicators" source: "https://en.wikipedia.org/wiki/Methyl_yellow" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Watchedfields = changed | verifiedrevid = 462250782 | ImageFile = Methyl yellow.svg | ImageSize = | PIN = N,N-Dimethyl-4-(phenyldiazenyl)aniline | OtherNames = 4-Dimethylaminoazobenzene p-Dimethylaminoazobenzene DAB N,N-Dimethyl-4-phenylazoaniline N,N-Dimethyl-4-aminoazobenzene Butter Yellow Solvent Yellow 2 C.I. 11020 |Section1={{Chembox Identifiers | ChemSpiderID_Ref = | ChemSpiderID = 5829 | UNII_Ref = | UNII = A49L8E13FD | InChI = 1/C14H15N3/c1-17(2)14-10-8-13(9-11-14)16-15-12-6-4-3-5-7-12/h3-11H,1-2H3/b16-15+ | InChIKey = JCYPECIVGRXBMO-FOCLMDBBBF | StdInChI_Ref = | StdInChI = 1S/C14H15N3/c1-17(2)14-10-8-13(9-11-14)16-15-12-6-4-3-5-7-12/h3-11H,1-2H3/b16-15+ | StdInChIKey_Ref = | StdInChIKey = JCYPECIVGRXBMO-FOCLMDBBSA-N | CASNo = 60-11-7 | CASNo_Ref = | EINECS = 200-455-7 | ChEMBL_Ref = | ChEMBL = 263116 | PubChem = 6053 | SMILES = N(=N/c1ccccc1)\c2ccc(N(C)C)cc2 | RTECS = BX7350000 |Section2={{Chembox Properties | C=14 | H=15 | N=3 | Appearance = Yellow crystals | Density = | MeltingPtC = 111-116 | MeltingPt_notes = decomposes | BoilingPt = | LogP = 4.58 | Solubility = 13.6 mg/l |Section3={{Chembox Hazards | GHSPictograms = | GHSSignalWord = Danger | HPhrases = | PPhrases = | NFPA-H = 2 | NFPA-F = 1 | NFPA-R = 0 | NFPA-S = | FlashPt = | AutoignitionPt = | MainHazards = Carcinogen | PEL = OSHA-regulated carcinogen | IDLH = Ca [N.D.] | REL = Ca

Methyl yellow, or C.I. 11020, is an organic compound with the formula C6H5N2C6H4N(CH3)2. It is an azo dye derived from dimethylaniline. It is a yellow solid. According to X-ray crystallography, the C14N3 core of the molecule is planar.

It is used as a dye for plastics and may be used as a pH indicator. In aqueous solution at low pH, methyl yellow appears red. Between pH 2.9 and 4.0, methyl yellow undergoes a transition, to become yellow above pH 4.0.

Safety

It is a possible carcinogen.

History

Butter yellow was synthesized by Peter Griess in the 1860s at the Royal College of Chemistry in London. The dye was used to dye butter in Germany and other parts of the world during the latter half of the 19th century and the beginning of the 20th before being phased out in the 1930s and 40s. It was in the 1930s that research led by Riojun Kinosita showed the link between several azo dyes and cancer, linking butter yellow to liver cancer in rats after two to three months exposure. In 1939, the International Congress for Cancer Research issued a recommendation for the banning of cancer-causing food dyes (including butter yellow) from food production.

In 2014, dried tofu products such as dougan (豆乾) from Taiwan were found to have been adulterated with methyl yellow which was used as a coloring agent.

References

References

  1. [https://www.sigmaaldrich.com/US/en/product/sial/73225 Dimethyl yellow]
  2. {{PGCH. 0220
  3. (1992). "Crystal and molecular structure of C.I. Solvent Yellow 2, 1-Phenylazo-4 (N,N-dimethylamine)-phenyl". Journal of Crystallographic and Spectroscopic Research.
  4. (September 1944). "The Pathogenesis of Tumors of the Liver Produced by Butter Yellow". The Journal of Experimental Medicine.
  5. (2016-04-22). "Gendered Drugs and Medicine: Historical and Socio-Cultural Perspectives". Routledge.
  6. Robert, Proctor. (1999). "The Nazi War on Cancer". Princeton University Press.
  7. (January 1940). "Studies on the Cancerogenic Azo and Related Compounds". The Yale Journal of Biology and Medicine.
  8. (17 December 2014). "Taiwan recalls tainted dried tofu in fresh food scare". Channel NewsAsia.

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ph-indicatorsazo-dyesanilinesiarc-group-2b-carcinogensdimethylamino-compounds