o-Anisidine (2-anisidine) is an organic compound with the formula CH3OC6H4NH2. A colorless liquid, commercial samples can appear yellow owing to air oxidation. It is one of three isomers of the methoxy-containing aniline derivative.
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| Names | |||
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| Preferred IUPAC name
2-Methoxyaniline[1] | |||
| Other names
ortho-Anisidine | |||
| Identifiers | |||
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3D model (JSmol) |
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| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.001.785 
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| EC Number |
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| KEGG |
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PubChem CID |
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| RTECS number |
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| UNII | |||
| UN number | 2431 | ||
CompTox Dashboard (EPA) |
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| Properties[2] | |||
| C7H9NO | |||
| Molar mass | 123.155 g·mol−1 | ||
| Appearance | Yellow liquid, turns brown upon exposure to air | ||
| Density | 1.0923 g/cm3 | ||
| Melting point | 6.2 °C (43.2 °F; 279.3 K) | ||
| Boiling point | 224 °C (435 °F; 497 K) | ||
| 1.5 g/100 ml | |||
| Solubility | soluble in ethanol, diethyl ether, acetone, benzene | ||
| -80.44·10−6cm3/mol | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards |
potential occupational carcinogen[3] | ||
| GHS labelling: | |||
 
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| Danger | |||
| H301, H311, H331, H341, H350 | |||
| P201, P202, P261, P264, P270, P271, P280, P281, P301+P310, P302+P352, P304+P340, P308+P313, P311, P312, P321, P322, P330, P361, P363, P403+P233, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 118 °C (244 °F; 391 K) (open cup) | ||
| 415 °C (779 °F; 688 K) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
2000 mg/kg (rat, oral) 1400 mg/kg (mouse, oral) 870 mg/kg (rabbit, oral)[4] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) |
TWA 0.5 mg/m3 [skin][3] | ||
REL (Recommended) |
: Ca TWA 0.5 mg/m3 [skin][3] | ||
IDLH (Immediate danger) |
50 mg/m3[3] | ||
| Related compounds | |||
Related compounds |
m-Anisidine p-Anisidine | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
It is prepared via methanolysis of 2-chloronitrobenzene:[5]
The resulting o-nitroanisole is reduced to o-anisidine.
o-Anisidine is used in the manufacture of dyes. It is nitrated to give 4-nitroanisidine. It is also a precursor to o-dianisidine.
One special use is as a heartwood indicator. An acid solution of o-anisidine is diazotized by adding a sodium nitrite solution. This mixture is applied to the wood and by reaction with polyphenols in the heartwood a reddish brown azo dye is formed.
o-Anisidine is a dangerous pollutant from the production of dyes. It is listed as RCRA hazardous waste, with the code K181.[6] The International Agency for Research on Cancer (IARC) has classified o-anisidine as a Group 2B, possible human carcinogen.[7]
The names 'toluidine', 'anisidine', and 'phenetidine' for which o-, m-, and p- have been used to distinguish isomers, and 'xylidine' for which numerical locants, such as 2,3-, have been used, are no longer recommended, nor are the corresponding prefixes 'toluidine', 'anisidino', 'phenetidine', and 'xylidino'.
