Dimethylaniline

This article is about N,N-dimethylaniline. For other constitutional isomers, see xylidine.

N,N-Dimethylaniline (DMA) is an organic chemical compound, a substituted derivative of aniline. It is a tertiary amine, featuring a 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.

N,N-Dimethylaniline

Names
Preferred IUPAC name N,N-Dimethylaniline
Other names DMA Dimethylaminobenzene N,N-Dimethylbenzeneamine N,N-Dimethylphenylamine
Identifiers
CAS Number	121-69-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:16269 Y
ChEMBL	ChEMBL371654 Y
ChemSpider	924 Y
ECHA InfoCard	100.004.085
KEGG	C02846 Y
PubChem CID	949
UNII	7426719369 Y
CompTox Dashboard (EPA)	DTXSID2020507
InChI InChI=1S/C8H11N/c1-9(2)8-6-4-3-5-7-8/h3-7H,1-2H3 Y Key: JLTDJTHDQAWBAV-UHFFFAOYSA-N Y
SMILES CN(C)c1ccccc1
Properties
Chemical formula	C8H11N
Molar mass	121.183 g·mol−1
Appearance	Colorless liquid
Odor	amine-like
Density	0.956 g/mL
Melting point	2 °C (36 °F; 275 K)
Boiling point	194 °C (381 °F; 467 K)
Solubility in water	2% (20°C)[1]
Vapor pressure	1 mmHg (20°C)[1]
Magnetic susceptibility (χ)	−89.66·10−6 cm3/mol
Hazards
Flash point	63 °C (145 °F; 336 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1410 mg/kg (rat, oral)[2]
LCLo (lowest published)	50 ppm (rat, 4 hr)[2]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 5 ppm (25 mg/m3) [skin][1]
REL (Recommended)	TWA 5 ppm (25 mg/m3) ST 10 ppm (50 mg/m3) [skin][1]
IDLH (Immediate danger)	100 ppm[1]
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation

DMA was first reported in 1850 by the German chemist A. W. Hofmann, who prepared it by heating aniline and iodomethane:^[3][4]

C₆H₅NH₂ + 2 CH₃I → C₆H₅N(CH₃)₂ + 2 HI

DMA is produced industrially by alkylation of aniline with methanol in the presence of an acid catalyst:^[5]

C₆H₅NH₂ + 2 CH₃OH → C₆H₅N(CH₃)₂ + 2 H₂O

Similarly, it is also prepared using dimethyl ether as the methylating agent.

Reactions

Dimethylaniline undergoes many of the reactions expected for an aniline, being weakly basic and reactive toward electrophiles.^[6]

It is nitrated to produce tetryl, a derivative with four nitro groups which was once used as explosive. In acidic solution, the initial nitration gives 3-nitrodimethylaniline.^[7] It reacts with butyllithium to give the 2-lithio derivative. Electrophilic methylating agents like dimethyl sulfate attack the amine to give the quaternary ammonium salt:^[8]

C₆H₅N(CH₃)₂ +(CH₃O)₂SO₂ → C₆H₅N(CH₃)₃CH₃OSO₃

Diethylaniline and dimethylaniline are both used as acid-absorbing bases.

Applications

DMA is a key precursor to commercially important triarylmethane dyes such as malachite green and crystal violet.^[9] DMA serves as a promoter in the curing of polyester and vinyl ester resins.^[10] 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.^[11]