There are three
isomers of toluidine, which are
organic compounds. These isomers are
''o''-toluidine, ''m''-toluidine, and ''p''-toluidine, with the prefixed letter abbreviating, respectively,
''ortho''; ''meta''; and ''para''. All three are
aryl amines whose
chemical structures are similar to
aniline except that a
methyl group is substituted onto the benzene ring. The difference between these three isomers is the position where the methyl group (–CH
3) is bonded to the ring relative to the
amino functional group (–NH
2); see illustration of the chemical structures below.
The chemical properties of the toluidines are quite similar to those of
aniline, and toluidines have properties in common with other
aromatic amines. Due to the amino group bonded to the aromatic ring, the toluidines are
weakly basic. The toluidines are poorly
soluble in pure
water but dissolve well in
acidic water due to formation of
ammonium
The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...
salts, as usual for organic amines. ''ortho''- and ''meta''-toluidines are viscous
liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
s, but ''para''-toluidine is a flaky
solid. This difference is related to the fact that the ''p''-toluidine
molecules are more symmetrical. ''p''-Toluidine can be obtained from
reduction of
''p''-nitrotoluene. ''p''-Toluidine reacts with
formaldehyde to form
Tröger's base
Tröger's base is a white solid tetracyclic organic compound. structure and formula of (CH3C6H3NCH2)2CH2. Tröger's base and its analogs are soluble in various organic solvents and strong acidic aqueous solutions due to their protonation.
History ...
.
Uses and occurrence
The ''ortho'' isomer is produced on the largest scale. Its primary application is as a precursor to the pesticides
metolachlor and
acetochlor.
[ The other toluidine isomers are used in the production of ]dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
s. They are a component of accelerators for cyanoacrylate
Cyanoacrylates are a family of strong fast-acting adhesives with industrial, medical, and household uses. They are derived from ethyl cyanoacrylate and related esters. The cyanoacrylate group in the monomer rapidly polymerizes in the presence ...
glues (for example sold as the brand name Zip Kicker).
In some patients ''o''-toluidine is a metabolite of prilocaine, which may cause methemoglobinemia
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications m ...
. This is then treated with methylene blue
Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. Methylene blue is a thiazine dye. As a medication, it is mainly used to treat methemoglobinemia by converting the ferric iron in hemoglobin ...
.
References
External links
MSDS
CDC – NIOSH Pocket to Chemical Hazards
{{Authority control
Anilines
Alkyl-substituted benzenes