Article · Wikipedia archive · Last revised Jun 9, 2026

Black 7984

Black 7984, Food Black 2, or C.I. 27755, is a brown-to-black synthetic diazo dye. It is often used as the tetrasodium salt.

Last revised
Jun 9, 2026
Read time
≈ 1 min
Length
334 w
Citations
7
Source
Wikipedia ↗
Black 79841
source ↗
Names
IUPAC name
Tetrasodium 6-amino-4-hydroxy-3-[[7-sulfonato-4-[(4-sulfonatophenyl)azo]-1-naphthyl]azo]naphthalene-2,7-disulfonate
Other names
  • Food Black 2
  • C.I. 27755
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.016.661
EC Number
  • 218-326-9
  • InChI=1S/C26H19N5O13S4.4Na/c27-20-12-18-13(9-23(20)47(39,40)41)10-24(48(42,43)44)25(26(18)32)31-30-22-8-7-21(17-6-5-16(11-19(17)22)46(36,37)38)29-28-14-1-3-15(4-2-14)45(33,34)35;;;;/h1-12,30H,27H2,(H,33,34,35)(H,36,37,38)(H,39,40,41)(H,42,43,44);;;;/q;4*+1/p-4/b29-28?,31-25-;;;;
    Key: XAOPCPOUYMCJFA-PEEPPZCGSA-J
  • acid: InChI=1S/C26H19N5O13S4/c27-20-12-18-13(9-23(20)47(39,40)41)10-24(48(42,43)44)25(26(18)32)31-30-22-8-7-21(17-6-5-16(11-19(17)22)46(36,37)38)29-28-14-1-3-15(4-2-14)45(33,34)35/h1-12,32H,27H2,(H,33,34,35)(H,36,37,38)(H,39,40,41)(H,42,43,44)/b29-28+,31-30+
    Key: DUUHLAZWLLCPSP-DUJDKOHPSA-N
  • [O-]S(C(C=C4)=CC=C4/N=N/C(C=C2)=C3C(C=C(S([O-])(=O)=O)C=C3)=C2/N=N/C1=C(S([O-])(=O)=O)C=C(C=C(S([O-])(=O)=O)C(N)=C5)C5=C1O)(=O)=O.[Na+].[Na+].[Na+].[Na+]
  • acid: Nc1cc2c(O)c(/N=N/c3ccc(/N=N/c4ccc(S(=O)(=O)O)cc4)c4ccc(S(=O)(=O)O)cc34)c(S(=O)(=O)O)cc2cc1S(=O)(=O)O
Properties
C26H15N5Na4O13S4
Molar mass 825.63 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Black 7984, Food Black 2, or C.I. 27755, is a brown-to-black synthetic diazo dye. It is often used as the tetrasodium salt.

Production

In the synthesis of Food Black 2, sulfanilic acid 1 is first reacted with sodium nitrite under acid diazotization conditions, and the resulting diazonium salt 2 is subjected to azo coupling with 8-aminonaphthalene-2-sulfonic acid 3. The monoazo dye 4 is subsequently diazotized to form the diazonium compound 5 and then reacted with 3-amino-5-hydroxynaphthalene-2,7-disulfonic acid 6 to yield the diazo dye 7.2 synthesis of C.I. Food Black 2

Use

Under the designation E 152, Food Black 2 was approved in the EU as a food colorant by Directive 62/2645/EEC until the end of 1976.34

Food Black 2 is approved in the EU under Regulation (EC) No 1223/2009 as a colorant in cosmetics.5 Its use as a hair dye is not permitted.6

Together with Acid Yellow 23 and Acid Red 52, Food Black 2 is used in inks for inkjet printing.7

Black 7984 is also used in cosmetics.

See also

See also

References

References

  1. European chemical Substances Information System
  2. "Food Black 2". World dye variety. Retrieved 2022-01-27.
  3. Aufgenommen durch die EU-Richtlinie 1962 2645.
  4. Gestrichen durch die EU-Richtlinie 1976 399.
  5. EU-Verordnung 2009 1223, Anhang IV: Liste der in kosmetischen Mitteln zugelassene Farbstoffe, Laufende Nummer 52.
  6. EU-Verordnung 2013 344, Anhang II: Liste der Stoffe, die in kosmetischen Mitteln verboten sind, Laufende Nummer 1354.
  7. Ingo Klöckl (2015), Chemie der Farbmittel (In der Malerei), Berlin, München, Boston: De Gruyter, pp. 437 f., doi:10.1515/9783110374537, ISBN 978-3-11-037453-7