What are the azo dyes?

Dyes "azo" are the most important chemical class of dyes and colorants in the textile industry, while 70% of organic dyes on the market. Are used to color natural and synthetic fibers, food, candy, cosmetics and beverages

Dyes "azo" dyes are divided into soluble and insoluble pigments, soluble in turn water-soluble and fat soluble. Water-soluble dyes used in textile dyeing and fat-soluble dyes and pigments in printing.

Manufacture of dyes "azo"
The manufacture of dyes "azo" is called diazotization process by which an aromatic amine (also called diazo component) is transformed into a diazonium component which in turn reacts with a coupling component, which can be phenol, or Naphtol an amine to form the dye.

Providing a wide variety of diazo components and coupling components possible, the range of variation of the "Azo-dyes is very large. The number of combinations increases since the dye "azo" can have more of an azo compound.

The color-index of German textile industry includes more than 800 colors and 600 auxiliaries and finishing agents.
The dyes 'azo' can be: acidic, basic, mordant, reactive, disperse, direct, solvents or food dyes. Not all acid dyes are dyes' azo.

Production moving south
The dyes 'azo' are still increasing and it is very difficult to know their exact wording, as companies consider them trade secrets. Production also has been decentralized and "facilities" provided by emerging countries in terms of deregulation promotes the migration of industries from the center to the periphery, and the chemical industry is more comfortable in Bangalore and Chennai (India) in Basel ( Switzerland).

Many dirty production away from the restrictions in the EU or the U.S. but still continues to produce and distribute their products to the world. The customs regulations on dyes and dye is incredibly loose and generic.

  

No.

Sustancia

Código
CAS

1

4-aminodiphenyl 

92-67-1

2

benzidine  

92-87-5

3

4-chloro-o-toluidine 

95-69-2

4

2-naphthylamine   

91-59-8

5*

4-amino-2',3-dimethylazobenzene  

97-56-3

6*

2-amino-4-nitrotoluene 

99-55-8

7

4-chloroaniline

106-47-8

8

2,4-diaminoanisole

615-05-4

9

4,4'-diaminodiphenylmethane

101-77-9

10

3,3'-dichlorobenzidine

91-94-1

11

3,3'-dimethoxybenzidine

119-90-4

12

3,3'-dimethylbenzidine

119-93-7

13

3,3'-dimethyl-4,4'diaminodiphenylmethane

838-88-0

14

4-cresidine

120-71-8

15

4,4'-methylene-bis-(2-chloroaniline)

101-14-4

16

4,4'-oxydianiline

101-80-4

17

4,4'-thiodianiline

139-65-1

18

2-aminotoluene

95-53-4

19

2,4-diaminotoluene

95-80-7

20

2,4,5-trimethylaniline

137-17-7

21

2-methoxyaniline

90-04-0

22**

4-aminoazobenzene

60-09-3

* las aminas 5 y 6 son analizadas indirectamente via reducción a aminas 18 y 19 respectivamente

** no esta disponible un análisis para  4-aminoazobenzene