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CAS number 8064-60-6


Molecular formula C21H15N3O3S3 (free acid)
Molar mass 453.557 g/mol (free acid)
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Primuline is a dye containing the benzothiazole ring system. Primuline itself is also known as Direct yellow 7, Carnotine, or C.I. 49010.

The primulines are considered derivatives of dehydrothiotoluidine (aminobenzenyltoluylmercaptan), which is obtained when para-toluidine is heated with sulphur for eighteen hours at 180-190 °C and then for a further six hours at 200-220 °C[1] Dehydrothiotoluidine is not itself a dye-stuff, but if the heating is carried out at a higher temperature in the presence of more sulphur, then a base is formed, which gives primuline yellow upon sulphonation.[2]

Primuline yellow is a mixture of sodium salts and probably contains at least three thiazole rings in combination. It is a substantive cotton dye of rather fugitive shade, but can be diazotized on the fibre and then developed with other components, yielding a series of ingrain colors.

Primuline is usually available as a sodium salt. Primuline is fluorescent.

Thioflavin T is obtained by the methylation of dehydrothiotoluidine with methanol in the presence of hydrochloric acid. Thioflavin S results from the methylation of dehydrothiotoluidine with sulfonic acid. This sulfonic acid on oxidation with bleaching powder or with lead peroxide, in alkaline solution yields chloramine yellow, which dyes cotton a beautiful yellow.


  1. ^ P. Jacobson (1889). "N/A". Ber. 22: 333.
    L. Gatterrnann, ibid. p. 1084
  2. ^ A. G. Green (1888). "N/A". Journ. Soc. Chem. Ind. 1: 194.
  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Primuline". A list of authors is available in Wikipedia.
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