Primuline

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

Primuline
Names
IUPAC name
sodium;2-[2-(4-aminophenyl)-1,3-benzothiazol-6-yl]-6-methyl-1,3-benzothiazole-7-sulfonate
Other names
Direct yellow 59
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.698
EC Number
  • 233-781-3
Properties
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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Infobox references

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]

References

  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. Chisholm, Hugh, ed. (1911). "Primuline" . Encyclopædia Britannica. 22 (11th ed.). Cambridge University Press. p. 342.
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