Direct Black 38

Structural formula
General
Surname	CI Direct Black 38
other names	Disodium 4-amino-3 - [( E ) - {4 '- [( E ) - (2,4-diaminophenyl) diazenyl] -4-biphenylyl} diazenyl] -5-hydroxy-6 - [( E ) - phenyldiazenyl] -2,7-naphthalene disulfonate ( IUPAC ); Chlorazole Black E.; Direct deep black E.; Direct deep black EW; Direct deep black EAC; Azo Black;
Molecular formula	C 34 H 25 N 9 Na 2 O 7 S 2
Brief description	black solid
External identifiers / databases
EC number	217-710-3
ECHA InfoCard	100.016.101
PubChem	5284349
ChemSpider	17214995
Wikidata	Q27096169
properties
Molar mass	781.74 g mol −1
Physical state	firmly
safety instructions
H and P phrases	H: 319-350-361d
	P: 201-280-305 + 351 + 338-308 + 313
Authorization procedure under REACH	particularly worrying : carcinogenic ( CMR )
Toxicological data	7600 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Direct Black 38 ( CI 30235) is a trisazo dye from the class of direct dyes .

Synthesis and properties

The dye is synthesized by tetrazotization of benzidine and coupling to m- phenylenediamine and H-acid in the acidic pH range. The resulting bisazo dye is reacted with diazotized aniline under alkaline conditions to give the end product.

Under reductive conditions, the azo groups can be cleaved and the carcinogenic benzidine can be released. This is why Direct Black 38 is also classified as SVHC (Substances of Very High Concern, German: "Substances of very high concern").

use

Direct Black 38 was used in microscopy for staining mushrooms and other biological preparations.

Individual evidence

↑ ^a ^b ^c ^d ^e Entry on disodium 4-amino-3 - ((4 '- ((2,4-diaminophenyl) azo) (1,1'-biphenyl) -4-yl) azo) -5-hydroxy -6- (phenylazo) naphthalene-2,7-disulfonate Template: link text check / apostrophe in the GESTIS substance database of the IFA , accessed on January 20, 2019(JavaScript required) .
↑ Entry on CI Direct Black 38 in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on January 20, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Entry in the SVHC list of the European Chemicals Agency , accessed on January 20, 2019.
↑ World Dye Variety: Direct Black 38.Retrieved May 14, 2019 .
↑ Hans Theodor Bucherer: Textbook of color chemistry . 2nd Edition. Springer-Verlag, Berlin, Heidelberg 1921, p. 399 ( limited preview in Google Book search).
↑ W. Metheis: Chemical reagents in the hands of mycologists 2. Wed .: Some dyes for microscopy. Mushroom Science Journal, December 1975, accessed January 19, 2019 .

[GESTIS-1] Entry on disodium 4-amino-3 - ((4 '- ((2,4-diaminophenyl) azo) (1,1'-biphenyl) -4-yl) azo) -5-hydroxy -6- (phenylazo) naphthalene-2,7-disulfonate Template: link text check / apostrophe in the GESTIS substance database of the IFA , accessed on January 20, 2019(JavaScript required) .

[CLP_100.016.101-2] Entry on CI Direct Black 38 in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on January 20, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .

[SVHC-3] Entry in the SVHC list of the European Chemicals Agency , accessed on January 20, 2019.

[4] World Dye Variety: Direct Black 38.Retrieved May 14, 2019 .

[5] Hans Theodor Bucherer: Textbook of color chemistry . 2nd Edition. Springer-Verlag, Berlin, Heidelberg 1921, p. 399 ( limited preview in Google Book search).

[6] W. Metheis: Chemical reagents in the hands of mycologists 2. Wed .: Some dyes for microscopy. Mushroom Science Journal, December 1975, accessed January 19, 2019 .