p-Anisidine (orpara-anisidine) is an organic compound with the formula CH3OC6H4NH2. A white solid, commercial samples can appear grey-brown owing to air oxidation. It is one of three isomers of anisidine, methoxy-containing anilines. It is prepared by reduction of 4-nitroanisole.[8]
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| Names | |||
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| Preferred IUPAC name
4-Methoxyaniline[1] | |||
| Other names
para-Anisidine; 4-Aminoanisole; p-Aminoanisole | |||
| Identifiers | |||
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3D model (JSmol) |
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| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.002.959 
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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[4] | |||
| C7H9NO | |||
| Molar mass | 123.155 g·mol−1 | ||
| Appearance | Light reddish brown solid[2] | ||
| Odor | Fishy[2] | ||
| Density | 1.071 (at 57 °C) | ||
| Melting point | 56 to 59 °C (133 to 138 °F; 329 to 332 K) | ||
| Boiling point | 243 °C (469 °F; 516 K) | ||
| Sparingly soluble[2] | |||
| Solubility in other solvents | Soluble in ethanol, diethyl ether, acetone, benzene | ||
| Vapor pressure | 0.006 mmHg (25 °C)[3] | ||
| -80.56·10−6cm3/mol | |||
Refractive index (nD) |
1.5559 | ||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards |
Carcinogen | ||
| GHS labelling: | |||
  
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| Warning | |||
| H300, H310, H330, H350, H373, H400[5] | |||
| P201, P202, P260, P262, P264, P270, P271, P273, P280, P281, P284, P301+P310, P302+P350, P304+P340, P308+P313, P310, P314, P320, P321, P322, P330, P361, P363, P391, P403+P233, P405, P501 | |||
| Flash point | 122 °C (252 °F; 395 K) | ||
| 515 °C (959 °F; 788 K) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
145 mg/kg (rabbit, oral)[6] 130 mg/kg (mouse, oral) 140 mg/kg (rat, oral)[7] | ||
LDLo (lowest published) |
100 mg/kg (mouse, oral)[7] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) |
TWA 0.5 mg/m3 [skin][3] | ||
REL (Recommended) |
TWA 0.5 mg/m3 [skin][3] | ||
IDLH (Immediate danger) |
50 mg/m3[3] | ||
| Related compounds | |||
Related compounds |
o-Anisidine m-Anisidine | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
p-Anisidine condenses readily with aldehydes and ketones to form Schiff bases, which absorb at 350 nm. This colorimetric reaction is used to test for the presence of oxidation products in fats and oils, an official method for detecting them by the American Oil Chemists' Society.[9] It is particularly good at detecting unsaturated aldehydes, which are the ones that are most likely to generate unacceptable flavors, making it particularly useful in food quality testing.[10][11]
p-Anisidine is a relatively toxic compound with a permissible exposure limit of 0.5 mg/m3.[2]
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'.
