Direct Red 2

Structural formula
General
Surname	Direct Red 2
other names	Disodium 3,3 ′ - [(3,3′-dimethyl-4,4′-biphenyldiyl) di-2,1-diazenediyl] bis (4-amino-1-naphthalenesulfonate) ( IUPAC ); CI 23500; Benzopurpurine 4B;
Molecular formula	C 34 H 26 N 6 Na 2 O 6 S 2
Brief description	red-brown solid
External identifiers / databases
EC number	213-594-3
ECHA InfoCard	100.012.359
PubChem	13816
ChemSpider	21171773
Wikidata	Q818516
properties
Molar mass	724.72 g mol −1
Physical state	firmly
Melting point	290 ° C
safety instructions
GHS labeling of hazardous substances danger
H and P phrases	H: 350
	P: 201-308 + 313
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

CI Direct Red 2 is a red coloring azo dye from the application technology group of direct dyes .

history

The dye was developed by Carl Duisberg and marketed under the name Benzopurpurin 4B. It is by the coupling of diazotized o -Tolidin with α-naphthionic accessible.

properties

Direct Red 2 dyes cotton red. The absorption maximum is 500 nm.

use

Direct Red 2 is a red dyeing cotton dye, it replaced the Congo red because it is more colourfast . Further, it is as a colorant in the microscopy ( vital staining ) and as pH - indicator used (color change from blue-violet to red between pH 2.3 and 4.0).

safety instructions

Since the carcinogenic o -Tolidine can be released again from Direct Red 2 under reductive conditions , this dye, like o -Tolidine itself, is one of the forbidden substances according to the Consumer Goods Ordinance (BedGgstV) and must not be used for textile and leather products that come into direct contact with human skin or the oral cavity for a long period of time (e.g. clothing, bed linen, towels, shoes, gloves, yarns and fabrics intended for end users).

Individual evidence

↑ ^a ^b ^c ^d ^e Entry on Benzopurpurin 4B. In: Römpp Online . Georg Thieme Verlag, accessed on February 9, 2014.
↑ ^a ^b Datasheet Benzopurpurine 4B from Sigma-Aldrich , accessed on November 7, 2016 ( PDF ).
↑ Appendix 1 (to § 3) of the Consumer Goods Ordinance (substances that may not be used in the manufacture or treatment of certain consumer goods)
^ Entry on benzidine-based azo dyes in the GESTIS substance database of the IFA , accessed on November 1, 2008(JavaScript required) .

[roempp-1] Entry on Benzopurpurin 4B. In: Römpp Online . Georg Thieme Verlag, accessed on February 9, 2014.

[Sigma-2] Datasheet Benzopurpurine 4B from Sigma-Aldrich , accessed on November 7, 2016 ( PDF ).

[3] Appendix 1 (to § 3) of the Consumer Goods Ordinance (substances that may not be used in the manufacture or treatment of certain consumer goods)

[GESTIS_2-4] Entry on benzidine-based azo dyes in the GESTIS substance database of the IFA , accessed on November 1, 2008(JavaScript required) .