o -Toluidine

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Structural formula
Structural formula of o-toluidine
General
Surname o -Toluidine
other names
  • ortho- toluidine
  • o- aminotoluene
  • ortho- aminotoluene
  • o -methylaniline
  • ortho methylaniline
  • 2-methylaniline
  • 2-aminotoluene
  • 1-amino-2-methylbenzene
  • o -Tolylamine
  • ortho- tolylamine
Molecular formula C 7 H 9 N
Brief description

colorless to red-brown liquid with a characteristic odor

External identifiers / databases
CAS number 95-53-4
EC number 202-429-0
ECHA InfoCard 100.002.209
PubChem 7242
ChemSpider 13854136
Wikidata Q311695
properties
Molar mass 107.16 g mol −1
Physical state

liquid

density

1.00 g cm −3

Melting point
  • −24.4 ° C (alpha form)
  • −16.3 ° C (beta form)
boiling point

200 ° C

Vapor pressure

0.18 mbar (20 ° C)

pK s value

4.44 (the conjugate acid BH + )

solubility

slightly soluble in water (15 g l −1 at 20 ° C)

Refractive index

1.5728

safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 08 - Dangerous to health 09 - Dangerous for the environment

danger

H and P phrases H: 301 + 331-319-350-400
P: 201-273-304 + 340-305 + 351 + 338-309 + 310
Authorization procedure under REACH

particularly worrying : carcinogenic ( CMR )

MAK

Switzerland: 0.1 ml m −3 or 0.5 mg m −3

Toxicological data
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

o -Toluidine is a chemical compound from the group of aromatic, simply methylated anilines and is isomeric to m -toluidine and p -toluidine .

Extraction and presentation

All three isomeric toluidines are produced from nitrotoluenes ( accessible from toluene by nitration ) by reduction. The reduction can be carried out on the one hand with iron, acetic acid and hydrochloric acid ( Béchamp reduction ). Today, catalytic hydrogenation with Raney nickel predominates . Lower, aliphatic alcohols ( methanol , ethanol , n- propanol or iso- propanol ) are often used here as solvents . The hydrogenation generally takes place at pressures between 3 bar and 20 bar H 2 pressure (so-called low-pressure hydrogenation) or at 20 to 50 bar (so-called medium-pressure hydrogenation ).

properties

o-Toluidine is a colorless liquid that gradually turns reddish brown in air and light, is difficult to ignite, has a characteristic odor and is sparingly soluble in water. It has a conductivity of 3.792 × 10 −5 –S / m at 25 ° C and a pH value of 7.4 at 20 ° C and a concentration of 1.4% by mass.

All Toluidine are weak bases , their (pK s values) are in the same order of magnitude as aniline (4,603).

According to Antoine, the vapor pressure functions result according to log 10 ( p ) = A− (B / ( T + C)) ( p in bar, T in K) as follows:

Vapor pressure functions of the toluidines
Type T in K A. B. C.
o -Toluidine 391.6-473.4 4.19168 1617.232 -87.126
m -toluidine 394.9-476.5 4.19983 1618.386 −90.631
p -toluidine 315-473.5 4.71884 1961,716 −57.0

use

The toluidines used to be of great importance almost exclusively as intermediate products for the production of dyes and pigments . Some herbicides are now also produced on the basis of these compounds. o - and p -Toluidin are important starting materials for the production of Chlortoluidinen and nitrided toluidines. In addition to toluidinesulfonic acids , these are used to manufacture pharmaceuticals , dyes and pigments.

The cresols can be obtained from the toluidines via diazotization (and subsequent “ boiling ”) .

o -Toluidine is the starting material for the production of the coupling component Naphtol AS -D. Important azo dyes based on o -toluidine are Acid Red 24 ( CI 16140), Solvent Red 26 (CI 26120) and Solvent Yellow 3 (CI 11160). It is also important as a precursor for the herbicides phenmedipham and chlordimeform .

Chemical structure Surname use
Toluidine1 6-chloro-2-methylaniline.svg
6-chloro-2-methylaniline for pharmaceuticals
Toluidine2 3-chloro-2-methylaniline.svg
3-chloro-2-methylaniline as a diazo component for Naphtol-AS developing dyes,

Starting material for 2,6-dichlorotoluene

Toluidine3 4-chloro-2-methylaniline.svg
4-chloro-2-methylaniline Diazo component for Naphtol-AS developing dyes,

Pre- product for indigo and thioindigo dyes , starting material for 2,5-dichlorotoluene

Toluidine4 5-chloro-2-methylaniline.svg
5-chloro-2-methylaniline Diazo component for Naphtol AS developing dyes
Toluidine5 2-aminotoluene-4-sulfonic acid.svg
2-aminotoluene-4-sulfonic acid as a diazo component for azo dyes
Toluidine6 2- (ethylamino) -toluene-4-sulfonic acid.svg
2- (ethylamino) toluene-4-sulfonic acid for the production of dyes
Toluidine7 2-aminotoluene-5-sulfonic acid.svg
2-aminotoluene-5-sulfonic acid as a diazo component for azo dyes
Toluidine8 2-amino-3-chlorotoluene-5-sulfonic acid.svg
2-amino-3-chlorotoluene-5-sulfonic acid Intermediate for the production of pyrazolone dyes ,

z. B. Acid Yellow 18 , CI 19020

Toluidine19-2-amino-6-chlorotoluene-3-sulfonic acid.svg
2-amino-6-chlorotoluene-3-sulfonic acid Intermediate product for azo dyes
Toluidine9 2-amino-6-chlorotoluene-4-sulfonic acid.svg
2-amino-6-chlorotoluene-4-sulfonic acid Intermediate for azo dyes,

z. B. Acid Brown 105 , CI 13530

safety instructions

The vapors of o -toluidine can form an explosive mixture with air ( flash point 85 ° C, ignition temperature 480 ° C). It attacks various plastics. After reductive cleavage of azo groups, it must not be released from textiles or leather products that come into direct contact with human skin for a longer period of time (Appendix 1 of the Consumer Goods Ordinance ).

Individual evidence

  1. a b c d e f g h i j k l m n Entry on o-toluidine in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  2. a b Zvi Rappoport (Ed.): CRC Handbook of Tables for Organic Compound Identification . 3 rd Edition, CRC Press / Taylor and Francis, Boca Raton, FL, 1967, ISBN 0-8493-0303-6 , Acid Dissociation Constants of Organic Bases in Aqueous Solution, S. 437th
  3. JS Bowers, Jr .: Toluidines in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, doi : 10.1002 / 14356007.a27_159 .
  4. Entry on o-toluidine 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 .
  5. Entry in the SVHC list of the European Chemicals Agency , accessed on July 15, 2014.
  6. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 95-53-4 or O-toluidine ), accessed on November 2, 2015.
  7. a b R. R. Dreisbach, SA Shrader: Vapor Pressure Temperature Data on Some Organic Compounds . In: Ind. Eng. Chem. Band 41 , no. 12 , 1949, pp. 2879-2880 , doi : 10.1021 / ie50480a054 .
  8. ^ Daniel R. Stull: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds . In: Ind. Eng. Chem. Band 39 , no. 4 , 1947, pp. 517-540 , doi : 10.1021 / ie50448a022 .