''N'',''N''-Dimethylaniline (DMA) is an
organic chemical compound, a substituted derivative of
aniline. It consists of a
tertiary amine, featuring dimethylamino group attached to a
phenyl group. This oily liquid is colourless when pure, but commercial samples are often yellow. It is an important precursor to dyes such as
crystal violet
Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antif ...
.
Preparation and reactions
DMA was first reported in 1850 by the German chemist
A. W. Hofmann, who prepared it by heating aniline and
iodomethane:
:C
6H
5NH
2 + 2 CH
3I → C
6H
5N(CH
3)
2 + 2
HI
DMA is produced industrially by
alkylation of
aniline with
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
in the presence of an acid catalyst:
[Kahl, Thomas ''et al.'' (2007) "Aniline" in ''Ullmann's Encyclopedia of Industrial Chemistry''. John Wiley & Sons: New York. ]
:C
6H
5NH
2 + 2
CH3OH → C
6H
5N(CH
3)
2 + 2 H
2O
Similarly, it is also prepared using
dimethyl ether
Dimethyl ether (DME; also known as methoxymethane) is the organic compound with the formula CH3OCH3,
(sometimes ambiguously simplified to C2H6O as it is an isomer of ethanol). The simplest ether, it is a colorless gas that is a useful precursor ...
as the methylating agent.
Dimethylaniline undergoes many of the reactions expected for an aniline, being weakly basic and reactive toward electrophiles. For example, it is
nitrated
In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols and ...
to produce
tetryl, a derivative with four
nitro
Nitro may refer to:
Chemistry
*Nitrogen, a chemical element and a gas except at very low temperatures, with which many compounds are formed:
**Nitro compound, an organic compound containing one or more nitro functional groups, -NO2
**Nitroalkene, ...
groups which was once used as explosive. It is lithiated with
butyllithium. Methylating agents attack the amine to give the quaternary ammonium salt:
:C
6H
5N(CH
3)
2 +
(CH3O)2SO2 → C
6H
5N(CH
3)
3CH
3OSO
3
Applications
DMA is a key precursor to commercially important
triarylmethane dyes such as
malachite green and
crystal violet
Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antif ...
. DMA serves as a promoter in the curing of polyester and vinyl ester resins. DMA is also used as a precursor to other organic compounds. A study of the in vitro metabolism of ''N,N''-dimethylaniline using guinea pig and rabbit preparations and GLC techniques has confirmed ''N''-demethylation and ''N''-oxidation as metabolic pathways, and has also established ring hydroxylation as a metabolic route. Its derivative 2,4-dimethylaniline is a recalcitrant degradant of the pesticide amitraz and is also an industrial pollutant which is genotoxic, teratogenic and carcinogenic.
References
{{reflist
Anilines
Dimethylamino compounds