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From Wikipedia, the free encyclopedia
Preferred IUPAC name
Sodium 2′-(4-aminophenyl)-6-methyl[2,6′-bi-1,3-benzothiazole]-7-sulfonate
Other names
Direct yellow 59
3D model (JSmol)
ECHA InfoCard 100.030.698 Edit this at Wikidata
EC Number
  • 233-781-3
  • InChI=1S/C21H15N3O3S3.Na/c1-11-2-8-16-18(19(11)30(25,26)27)29-21(24-16)13-5-9-15-17(10-13)28-20(23-15)12-3-6-14(22)7-4-12;/h2-10H,22H2,1H3,(H,25,26,27);/q;+1/p-1 checkY
  • InChI=1/C21H15N3O3S3.Na/c1-11-2-8-16-18(19(11)30(25,26)27)29-21(24-16)13-5-9-15-17(10-13)28-20(23-15)12-3-6-14(22)7-4-12;/h2-10H,22H2,1H3,(H,25,26,27);/q;+1/p-1
  • [Na+].[O-]S(=O)(=O)c1c(ccc2nc(sc12)c4ccc3nc(sc3c4)c5ccc(N)cc5)C
C21H15N3O3S3 (free acid)
Molar mass 453.557 g/mol (free acid)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 sulfur 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 sulfur, then a base is formed, which gives primuline yellow upon sulfonation.[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.[3]

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.[3]


  1. ^ P. Jacobson (1889). "N/A". Ber. 22: 333.
    L. Gatterrnann, ibid. p. 1084
  2. ^ A. G. Green (1888). "N/A". J. Soc. Chem. Ind. 1: 194.
  3. ^ a b Chisholm, Hugh, ed. (1911). "Primuline" . Encyclopædia Britannica. Vol. 22 (11th ed.). Cambridge University Press. p. 342.