Dimethylaniline
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.
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| Names | |||
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| Preferred IUPAC name
N,N-Dimethylaniline | |||
| Other names
DMA
Dimethylaminobenzene N,N-Dimethylbenzeneamine N,N-Dimethylphenylamine | |||
| Identifiers | |||
3D model (JSmol)
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| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.004.085 | ||
| KEGG | |||
PubChem CID
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| UNII | |||
CompTox Dashboard (EPA)
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| 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): | |||
LD50 (median dose)
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1410 mg/kg (rat, oral)[2] | ||
LCLo (lowest published)
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50 ppm (rat, 4 hr)[2] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 5 ppm (25 mg/m3) [skin][1] | ||
REL (Recommended)
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TWA 5 ppm (25 mg/m3) ST 10 ppm (50 mg/m3) [skin][1] | ||
IDLH (Immediate danger)
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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]- ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0223". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b "N,N-Dimethylaniline". Immediately Dangerous to Life or Health Concentrations. National Institute for Occupational Safety and Health.
- ^ 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
- ^ In 1850, August Hofmann announced his synthesis of methylaniline:
- Hofmann, A. W. (1850) "Researches regarding the molecular constitution of the volatile organic bases," Philosophical Transactions of the Royal Society of London, 140 : 93–131 ; see especially pp. 113-114.
- Kern, A. (1877) "Ueber die Darstellung von Monomethylanilin" (On the preparation of monomethylaniline), Berichte der deutschen chemischen Gesellschaft, 10 : 195–199.
- Hofmann, A. W. (1877) "Versuche über die Einwirkung des Chlor-, Brom- und Jodmethyls auf Anilin" (Experiments on the reaction of methyl chloride, bromide and iodide with aniline), Berichte der deutschen chemischen Gesellschaft, 10 : 591–601.
- ^ Kahl, Thomas et al. (2007) "Aniline" in Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons: New York. doi:10.1002/14356007.a02_303
- ^ Brewster, R. Q.; Schroeder, Wesley (1939). "P-Thiocyanatodimethylaniline". Organic Syntheses. 19: 79. doi:10.15227/orgsyn.019.0079.
- ^ Howard M. Fitch (1947). "m-Nitrodimethylaniline". Organic Syntheses. 27: 62. doi:10.15227/orgsyn.027.0062..
- ^ 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). - ^ 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
- ^ General Info on DMA (N,N-Dimethylaniline), Composites Australia
- ^ 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.