p -toluidine
Structural formula | |||||||||||||||||||
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General | |||||||||||||||||||
Surname | p -toluidine | ||||||||||||||||||
other names |
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Molecular formula | C 7 H 9 N | ||||||||||||||||||
Brief description |
colorless to red-brown solid with a wine-like odor |
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External identifiers / databases | |||||||||||||||||||
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properties | |||||||||||||||||||
Molar mass | 107.16 g mol −1 | ||||||||||||||||||
Physical state |
firmly |
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density |
1.05 g cm −3 |
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Melting point |
45 ° C |
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boiling point |
200 ° C |
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Vapor pressure |
2.1 mbar (50 ° C) |
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pK s value |
5.08 (the conjugate acid BH + ) |
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solubility |
poorly soluble in water (7.5 g l −1 at 20 ° C) |
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Refractive index |
1.5534 |
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safety instructions | |||||||||||||||||||
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MAK |
Switzerland: 0.2 ml 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 |
p -Toluidine is a chemical compound from the group of aromatic, singly methylated anilines and is isomeric to o -toluidine and m -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 . The solvents used here are often lower, aliphatic alcohols ( methanol , ethanol , n-propanol or iso-propanol ). 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
p -Toluidine is a flammable, colorless to yellowish solid, which turns reddish-brown when exposed to light and air, has a wine-like odor and is sparingly soluble in water. It has a conductivity of 6.2 × 10 −6 S / m at 100 ° C.
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 . 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 ”) .
p -Toluidine is used as a reagent for lignin, nitrite, phloroglucinol and is used in the production of dyes , textile auxiliaries and vulcanization accelerators.
Important azo dyes based on p -toluidine are the cationic dye C.I. Basic Red 9 ( CI 42500) and the acid dye CI Acid Green 25 (CI 61570).
Via diazotization and subsequent reduction of the p -toluidine, p -tolylhydrazine (cf. hydrazine ) can be obtained, which is used as a precursor for 3-methyl-1- [ p -tolyl] -5-pyrazolone (important intermediate dye; cf. also : Pyrazolone ) is used.
For the production of triphenylmethane dyes and for 2,9-dimethylquinacridone (cf. quinacridone pigments ), p -toluidine is also used in large quantities.
Furthermore, it is also used for the production of some pesticides such as Oxythiochinox , tolylfluanid or safeners daimuron and many pharmaceuticals.
Chemical structure | Surname | use |
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3-chloro-4-methylaniline | for the production of 3-chloro-4-methyl-6-nitroaniline in order to obtain the herbicide chlorotoluron from it; in the USA as an avicide against starlings and gulls | |
4-aminotoluene-2-sulfonic acid | as an intermediate for azo dyes and optical brighteners | |
4-aminotoluene-3-sulfonic acid | serves (after diazotization and reduction to the corresponding hydrazine) for the production of important pyrazolones | |
4-aminotoluene-2-sulfonic acid anilide | as a diazo component for azo dyes | |
4-amino-6-chlorotoluene-3-sulfonic acid | as a diazo component for azo dyes and precursor for pyrazolones |
safety instructions
The vapors of p -toluidine can form an explosive mixture with air ( flash point 87 ° C, ignition temperature 482 ° C).
Individual evidence
- ↑ a b c d e f g h i j k l m entry on p-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
- ↑ a b J.S. 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 p-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 .
- ↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 106-49-0 or p-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 .
- ↑ James F. Glahn: Use Of Starlicide To Reduce Starling Damage At Livestock Feeding Operations , University of Nebraska - Lincoln, 1981.