Methyl yellow
chemical compound
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. As "butter yellow", the agent had been used as a food additive in butter and margarine before its toxicity was recognized.
History
Butter yellow was synthesized by Peter Griess in the 1860s at the Royal College of Chemistry in London.
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