Benzidine

Structural formula
General
Surname	Benzidine
other names	4- (4-aminophenyl) aniline ( IUPAC ) ; 4,4'-diaminobiphenyl; 1-amino-4- (4-aminophenyl) benzene; 4,4'-bianiline; Paradiaminobiphenyl; CI 37225;
Molecular formula	C 12 H 12 N 2
Brief description	yellow prisms
External identifiers / databases
EC number	202-199-1
ECHA InfoCard	100,002,000
PubChem	7111
Wikidata	Q410066
properties
Molar mass	184.24 g · mol -1
Physical state	firmly
density	1.25 g cm −3
Melting point	127.5-128.7 ° C
boiling point	401.7 ° C (987 h Pa )
solubility	very poor in water (400 mg l −1 at 12 ° C), ethanol , acetone and diethyl ether ; soluble in alkalis and glacial acetic acid ;
safety instructions
H and P phrases	H: 302-350-410
	P: 201-273-308 + 313-501
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Benzidine bottle, around 1910

Benzidine is a derivative of biphenyl . It is a safe carcinogen for humans . After contact with this substance, bladder tumors often develop after a latency period of several years . Benzidine can easily be absorbed through the skin , but also by inhalation of vapor or dust . Benzidine has a blood-damaging and weakening effect on the bone marrow . Long-term exposure can lead to methaemoglobin formation and anemia. Bladder and urothelial carcinomas occur more frequently .

presentation

Benzidine can be made from hydrazobenzene through the benzidine rearrangement .

use

Benzidine sample

In the past, the so-called benzidine probe (developed by O. and R. Alder around 1900) was used in medicine to detect blood , for example in stool . Together with hydrogen peroxide, this leads to oxidation and a blue coloration due to benzidine blue . This examination was also common in forensic medicine . In the meantime, blood is detected using less dangerous and specific methods, for example the modified guaiacol test according to Greegor (Haemoccult).

Benzidine dyes

Benzidine and compounds derived from benzidine, such as 3,3'-dimethylbenzidine , 3,3'-dimethoxybenzidine or 3,3'-dichlorobenzidine , are used as diazo components in the production of azo dyes . In the past, these dyes played an important role as direct dyes for dyeing cotton. Since benzidine can be released again from these dyes under reductive conditions, they belong, like benzidine itself, to the forbidden substances according to the Consumer Goods Ordinance (BedGgstV) and may not be used for textile and leather products that have been in contact with human skin for a long time Oral cavity (e.g. clothing, bed linen, towels, shoes, gloves, yarns and fabrics intended for end users).

toxicology

The carcinogenic potential of benzidine has been proven experimentally. In test animals it (like many aromatic amines ) mainly induces bladder cancer . Benzidine is mainly acetylated and / or hydroxylated on nitrogen in the body . A direct formation of two imine groups is also possible . All metabolic end products are ultimate carcinogens and mainly form DNA adducts with guanine .

Web links

International Chemical Safety Card (ICSC) for Benzidines at the National Institute for Occupational Safety and Health (NIOSH).

Individual evidence

↑ ^a ^b ^c Entry on benzidine. In: Römpp Online . Georg Thieme Verlag, accessed on July 5, 2014.
↑ ^a ^b ^c ^d ^e ^f Entry on benzidine in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ Entry on Benzidines in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Jürgen Thorwald : The hour of the detectives. Becomes and worlds of criminology. Droemer Knaur, Zurich and Munich 1966, p. 51.
↑ Consumer Goods Ordinance, Appendix 1 (to Section 3). Substances that may not be used in the manufacture or treatment of certain commodities. Federal Ministry of Justice and Consumer Protection, accessed on October 29, 2019 .
^ Entry on benzidine-based azo dyes in the GESTIS substance database of the IFA , accessed on November 1, 2008(JavaScript required) .
↑ G. Eisenbrand, M. Metzler: Toxicology for Chemists. Georg Thieme Verlag, Stuttgart 1994, ISBN 3-13-127001-2 , p. 181.

[roempp-1] Entry on benzidine. In: Römpp Online . Georg Thieme Verlag, accessed on July 5, 2014.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f Entry on benzidine in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[CLP_100.002.000-3] Entry on Benzidines in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[4] Jürgen Thorwald : The hour of the detectives. Becomes and worlds of criminology. Droemer Knaur, Zurich and Munich 1966, p. 51.

[5] Consumer Goods Ordinance, Appendix 1 (to Section 3). Substances that may not be used in the manufacture or treatment of certain commodities. Federal Ministry of Justice and Consumer Protection, accessed on October 29, 2019 .

[GESTIS_2-6] Entry on benzidine-based azo dyes in the GESTIS substance database of the IFA , accessed on November 1, 2008(JavaScript required) .

[7] G. Eisenbrand, M. Metzler: Toxicology for Chemists. Georg Thieme Verlag, Stuttgart 1994, ISBN 3-13-127001-2 , p. 181.