o -Toluidine
Structural formula | |||||||||||||||||||
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General | |||||||||||||||||||
Surname | o -Toluidine | ||||||||||||||||||
other names |
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Molecular formula | C 7 H 9 N | ||||||||||||||||||
Brief description |
colorless to red-brown liquid with a characteristic odor |
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External identifiers / databases | |||||||||||||||||||
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properties | |||||||||||||||||||
Molar mass | 107.16 g mol −1 | ||||||||||||||||||
Physical state |
liquid |
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density |
1.00 g cm −3 |
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Melting point | |||||||||||||||||||
boiling point |
200 ° C |
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Vapor pressure |
0.18 mbar (20 ° C) |
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pK s value |
4.44 (the conjugate acid BH + ) |
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solubility |
slightly soluble in water (15 g l −1 at 20 ° C) |
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Refractive index |
1.5728 |
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safety instructions | |||||||||||||||||||
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Authorization procedure under REACH |
particularly worrying : carcinogenic ( CMR ) |
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MAK |
Switzerland: 0.1 ml m −3 or 0.5 mg m −3 |
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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:
Type | T in K | A. | B. | C. |
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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 |
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6-chloro-2-methylaniline | for pharmaceuticals | |
3-chloro-2-methylaniline | as a diazo component for Naphtol-AS developing dyes,
Starting material for 2,6-dichlorotoluene |
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4-chloro-2-methylaniline | Diazo component for Naphtol-AS developing dyes,
Pre- product for indigo and thioindigo dyes , starting material for 2,5-dichlorotoluene |
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5-chloro-2-methylaniline | Diazo component for Naphtol AS developing dyes | |
2-aminotoluene-4-sulfonic acid | as a diazo component for azo dyes | |
2- (ethylamino) toluene-4-sulfonic acid | for the production of dyes | |
2-aminotoluene-5-sulfonic acid | as a diazo component for azo dyes | |
2-amino-3-chlorotoluene-5-sulfonic acid | Intermediate for the production of pyrazolone dyes ,
z. B. Acid Yellow 18 , CI 19020 |
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2-amino-6-chlorotoluene-3-sulfonic acid | Intermediate product for azo dyes | |
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
- ↑ 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) .
- ↑ 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
- ↑ 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 .
- ↑ 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 .
- ↑ Entry in the SVHC list of the European Chemicals Agency , accessed on July 15, 2014.
- ↑ 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.
- ↑ 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 .
- ^ 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 .