Aminophenols

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Aminophenols (also hydroxyanilines ; empirical formula C 6 H 7 NO) are aromatic compounds and are derived from both aniline and phenol . The different arrangement of the substituents results in three constitutional isomers . They serve u. a. for the manufacture of drugs, dyes and photographic developers . The methyl ethers form the group of anisidines , the ethyl ethers that of the phenetidines .

Representative

Aminophenols
Surname 2-aminophenol 3-aminophenol 4-aminophenol
other names o -aminophenol,
2-hydroxyaniline 		m -aminophenol,
3-hydroxyaniline 		p -aminophenol,
4-hydroxyaniline
Structural formula O-aminophenol.svg M-Aminophenol.svg P-aminophenol.svg
CAS number 95-55-6 591-27-5 123-30-8
27598-85-2 (mixture of isomers)
ECHA InfoCard 100.002.211 100.008.830 100.004.198
PubChem 5801 11568 403
Molecular formula C 6 H 7 NO
Molar mass 109.13 g mol −1
Physical state firmly
Brief description colorless solid
Melting point 172-174 ° C 122 ° C 190 ° C
boiling point 150 ° C (15 mbar ) 164 ° C (15 mbar) 284 ° C (dec.)
pK s value 9.71 9.87 10.30
solubility 17 g l −1 (20 ° C) 26 g l −1 (20 ° C) 6.5 g l −1 (24 ° C)
Slightly soluble in water, soluble in ethanol, ethers, acids and bases
GHS
labeling
from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
07 - Warning 08 - Dangerous to health
Caution 		from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
07 - Warning 09 - Dangerous for the environment
Caution 		from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
08 - Dangerous to health 07 - Warning 09 - Dangerous for the environment
Caution
H and P phrases 341-332-302 332-302-411 302-332-317-341-373-410
no EUH phrases no EUH phrases no EUH phrases
281 273 273-280-302 + 352-314
Tox data 951 mg kg −1 ( LD 50 ,  rat ,  oral ) 924 mg kg −1 ( LD 50 ,  rat ,  oral ) 375 mg kg −1 ( LD 50 ,  rat ,  oral )

Naming

In contrast to numerous disubstituted benzenes, aminophenols have not developed their own common name .

Just as the anise idine from ordinary registered anise oil or Tolu idine of Tolu ol derived (nitrogen-containing derivatives of anisole or toluene), would be the basis of the registered common Phen analogously ol naming Phen idine can be derived. This did not happen, however, the name phenidine is used for N- (4-ethoxyphenyl) acetamide (=  phenacetin ).

properties

The aminophenols are solid, colorless substances. They turn gray to dark gray when exposed to air. They are sparingly soluble in water, soluble in ethanol and ether . Since they have both a hydroxyl group and an amino group , they are soluble in acids and bases . In basic medium 2- and 4-aminophenol can of strong oxidizing agents reversibly to the corresponding quinone be implemented (see. Indophenol , see also quinones ).

presentation

4-aminophenol is produced by the electrolytic reduction of 4-nitrophenol in a strong sulfuric acid solution.

use

The dye indophenol can be produced by the oxidative coupling of 4-aminophenol with phenol in an alkaline solution with sodium hypochlorite as the oxidizing agent. The aminophenols are also used to represent numerous azo dyes .

Momme Andresen discovered in 1888 that 4-aminophenol can be used as a developer for black and white photography . It is known by the trade name Rodinal .

From 4-aminophenol derive u. a. Phenacetin and paracetamol . They both serve as drugs to treat pain and lower fever.

Reaction of 4-aminophenol with acetic anhydride leads to paracetamol with elimination of acetic acid .

The polycondensation of aminophenols with formaldehyde gives synthetic resins which have become important as anion exchangers .

Individual evidence

  1. ↑ Entry on aminophenol, isomers in the GESTIS substance database of the IFA , accessed on August 11, 2016(JavaScript required) .
  2. ↑ a b c d e f g Entry on 2-aminophenol in the GESTIS substance database of the IFA , accessed on December 27, 2019(JavaScript required) .
  3. ↑ a b c d e f g Entry on 3-aminophenol in the GESTIS substance database of the IFA , accessed on December 27, 2019(JavaScript required) .
  4. ↑ a b c d e f g Entry on 4-aminophenol in the GESTIS substance database of the IFA , accessed on December 27, 2019(JavaScript required) .
  5. ↑ a b CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 .
  6. ↑ chem.wisc.edu: pKa Data , Compiled by R. Williams (PDF, 78 kB).
  7. ↑ Entry on 2-aminophenol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 11, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  8. ↑ Entry on 3-aminophenol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 11, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  9. ↑ Entry on 4-aminophenol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 11, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  10. ↑ a b Beyer / Walter: Textbook of Organic Chemistry , 19th edition, S. Hirzel Verlag, Stuttgart 1981, ISBN 3-7776-0356-2 , p. 527.

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