Anisole

Anisole

Names
IUPAC name Methoxybenzene
Other names Phenoxymethane Phenyl methyl ether
Identifiers
CAS Number	100-66-3
ChEBI	CHEBI:16579
ChEMBL	ChEMBL278024
ChemSpider	7238
Jmol interactive 3D	Image Image
KEGG	C01403
UNII	B3W693GAZH
InChI InChI=1S/C7H8O/c1-8-7-5-3-2-4-6-7/h2-6H,1H3 Key: RDOXTESZEPMUJZ-UHFFFAOYSA-N InChI=1/C7H8O/c1-8-7-5-3-2-4-6-7/h2-6H,1H3 Key: RDOXTESZEPMUJZ-UHFFFAOYAP
SMILES O(c1ccccc1)C COc1ccccc1
Properties
Chemical formula	C7H8O
Molar mass	108.14 g·mol^−1
Appearance	Colorless liquid
Density	0.995 g/cm^3
Melting point	−37 °C (−35 °F; 236 K)
Boiling point	154 °C (309 °F; 427 K)
Solubility	Insoluble
Hazards
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	3700 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Anisole, or methoxybenzene, is an organic compound with the formula CH₃OC₆H₅. It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is mainly made synthetically and is a precursor to other synthetic compounds. It is an ether.

Reactivity

Anisole undergoes electrophilic aromatic substitution reaction more quickly than does benzene, which in turn reacts more quickly than nitrobenzene. The methoxy group is an ortho/para directing group, which means that electrophilic substitution preferentially occurs at these three sites. The enhanced nucleophilicity of anisole vs benzene reflects the influence of the methoxy group, which renders the ring more electron-rich. The methoxy group strongly affects the pi cloud of the ring as a mesomeric electron donor, more so than as an inductive electron withdrawing group despite the electronegativity of the oxygen.

Illustrative of its nucleophilicity, anisole reacts with acetic anhydride to give 4-methoxyacetophenone:

CH₃OC₆H₅ + (CH₃CO)₂O → CH₃OC₆H₄C(O)CH₃ + CH₃CO₂H

Unlike most acetophenones, but reflecting the influence of the methoxy group, methoxyacetophenone undergoes a second acetylation. Many related reactions have been demonstrated. For example, P₄S₁₀ converts anisole to Lawesson's reagent, [(CH₃OC₆H₄)PS₂]₂.

The ether linkage is highly stable, but the methyl group can be removed with hydroiodic acid:

CH₃OC₆H₅ + HI → HOC₆H₅ + CH₃I

Preparation

Anisole is prepared by the Williamson ether synthesis, reacting sodium phenoxide with methyl bromide and related methylating reagents:^[1]

C₆H₅O⁻Na⁺ + CH₃Br → CH₃OC₆H₅ + NaBr

Applications

Anisole is a precursor to perfumes, insect pheromones, and pharmaceuticals.^[2] For example, synthetic anethole is prepared from anisole.

Safety

Anisole is relatively nontoxic with an LD₅₀ of 3700 mg/kg in rats.^[3] Its main hazard is its flammability.^[3]

See also

• Anethole
• Bromoanisole
• Butylated hydroxyanisole
• Ether
• Ethyl phenyl ether
• Phenol
• 2,4,6-Trichloroanisole (cork taint)

References

1. G. S. Hiers and F. D. Hager (1941). "Anisole". Org. Synth.; Coll. Vol. 1, p. 58
2. Helmut Fiege, Heinz-Werner Voges, Toshikazu Hamamoto, Sumio Umemura, Tadao Iwata, Hisaya Miki, Yasuhiro Fujita, Hans-Josef Buysch, Dorothea Garbe, Wilfried Paulus “Phenol Derivatives“ in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_313
3. MSDS

External links

• International Chemical Safety Card 1014
• Pherobase pheromone database entry