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Dimethylaniline

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N,N-Dimethylaniline
Skeletal formula of dimethylaniline
Ball-and-stick model of the dimethylaniline molecule
Names
Preferred IUPAC name
N,N-Dimethylaniline
Other names
DMA
Dimethylaminobenzene
N,N-Dimethylbenzeneamine
N,N-Dimethylphenylamine
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.085 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C8H11N/c1-9(2)8-6-4-3-5-7-8/h3-7H,1-2H3 checkY
    Key: JLTDJTHDQAWBAV-UHFFFAOYSA-N checkY
  • CN(C)c1ccccc1
Properties
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)
2% (20°C)[1]
Vapor pressure 1 mmHg (20°C)[1]
-89.66·10−6 cm3/mol
Hazards
Flash point 63 °C (145 °F; 336 K)
Lethal dose or concentration (LD, LC):
1410 mg/kg (rat, oral)[2]
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).
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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.

Preparation

[edit]

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

[edit]

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

[edit]

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]

References

[edit]
  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0223". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b "N,N-Dimethylaniline". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ Watts, Henry, A Dictionary of Chemistry and the Allied Branches of Other Sciences, Part 2, (London, England: Longmans, Green, and Co., 1881), Methylanilines, p. 1306
  4. ^ In 1850, August Hofmann announced his synthesis of methylaniline: However, in 1877, the Swiss chemist Alfred Kern (1850–1893) contended that Hofmann's reaction produced only dimethylaniline, not methylaniline: Hofmann found that acetic anhydride reacted only with methylaniline, not with dimethylaniline, and was thus able to show that his reaction produced both the mono- and di-methylated forms of aniline:
  5. ^ Kahl, Thomas et al. (2007) "Aniline" in Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons: New York. doi:10.1002/14356007.a02_303
  6. ^ Brewster, R. Q.; Schroeder, Wesley (1939). "P-Thiocyanatodimethylaniline". Organic Syntheses. 19: 79. doi:10.15227/orgsyn.019.0079.
  7. ^ Howard M. Fitch (1947). "m-Nitrodimethylaniline". Organic Syntheses. 27: 62. doi:10.15227/orgsyn.027.0062..
  8. ^ Jacques, J. and Marquet, A. (1973). "Selective α-Bromination of an Aralkyl Ketone with Phenyltrimethylammonium Tribromide: 2-Bromoacetyl-6-methoxynaphthalene and 2,2-Dibromoacetyl-6-Methoxynaphthalene". Organic Syntheses. 53: 111. doi:10.15227/orgsyn.053.0111{{cite journal}}: CS1 maint: multiple names: authors list (link).
  9. ^ Gessner, Thomas and Mayer, Udo (2002) "Triarylmethane and Diarylmethane Dyes" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim.doi:10.1002/14356007.a27_179
  10. ^ General Info on DMA (N,N-Dimethylaniline), Composites Australia
  11. ^ Gorrod, J. W.; Gooderham, N. J. (1981). "The in vitro metabolism of N,N-dimethylaniline by guinea pig and rabbit tissue preparations". European Journal of Drug Metabolism and Pharmacokinetics. 6 (3): 195–206. doi:10.1007/BF03189489. PMID 7308239. S2CID 7221074.