o -Toluidine

Structural formula
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
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
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	670 mg kg −1 ( LD 50 , rat , oral ) ; 3260 mg kg −1 ( LD 50 , rabbit , transdermal ) ;
	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
	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
	4-chloro-2-methylaniline	Diazo component for Naphtol-AS developing dyes, Pre- product for indigo and thioindigo dyes , starting material for 2,5-dichlorotoluene
	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
	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 .

[GESTIS-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) .

[CRC_O-2] 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

[Ullmann-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 .

[CLP_100.002.209-4] 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 .

[SVHC-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.

[Dreisbach-7] 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 .

[Stull-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 .