Metol

from Wikipedia, the free encyclopedia
Structural formula
Structure of Metol
General
Surname Metol
other names
  • 4- (methylamino) phenol sulfate
  • N -methyl- p -aminophenol sulfate
  • Temal
  • Photo rex
Molecular formula C 14 H 20 N 2 O 6 S
Brief description

colorless odorless solid

External identifiers / databases
CAS number 55-55-0
EC number 200-237-1
ECHA InfoCard 100,000,216
PubChem 5930
Wikidata Q424581
properties
Molar mass 344.39 g mol −1
Physical state

firmly

Melting point

260 ° C ( decomposition )

solubility

moderate in water (47.9 g l −1 at 15 ° C)

safety instructions
GHS hazard labeling 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 H: 302-317-373-410
P: 260-280-301 + 312 + 330
Toxicological data

237 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 .

Metol , called 4- (methylamino) phenol sulfate according to IUPAC or also Temal or Photo-Rex , is a harmful salt of methylamino phenol . On the benzene ring , counting from the phenolic hydroxyl group in the para or 4 position, it has a singly methylated , protonated amino group . A sulfate ion acts as a counter ion . Due to the stoichiometric ratio, two 4- (methylamino) phenol cations are present per sulfate anion.

use

Metol is in black and white photography as a developer for black and white films and black and white photographic paper and in combination with other developing substances such as hydroquinone , catechol or phenidone used. A standard formulation with Metol and hydroquinone is the film developer Ilford ID-11 or Kodak D-76 , which makes use of the superaddition effect of the two developer substances .

safety instructions

Metol is irritating to eyes, skin and respiratory tract. It is harmful to health and sensitizing in contact with the skin and if swallowed. Metol is very hazardous to water and is therefore classified as dangerous for the environment.

Individual evidence

  1. ↑ a b c d e Entry on bis (4-hydroxy-N-methylanilinium) sulfate in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
  2. ↑ Entry on Bis (4-hydroxy-N-methylanilinium) sulphate 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 .
  3. ↑ Metol data sheet (PDF) from Merck , accessed on January 19, 2011.