Anisole

Anisole
Names
	IUPAC name methoxybenzene
	Other names anisole; phenoxymethane; phenyl methyl ether
Identifiers
CAS Number	100-66-3 ;
3D model (JSmol)	Interactive image; Interactive image;
ChemSpider	7238 ;
ECHA InfoCard	100.002.615
UNII	B3W693GAZH ;
CompTox Dashboard (EPA)	DTXSID4041608 ;
	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
Density	0.995 g/cm³
Melting point	−37 °C
Boiling point	154 °C
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Anisole is the 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.

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, more so than the inductive effect of the electronegative 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, [(CH₃O₆H₄)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 a methyl bromide and related methylating reagents:^[1]

2 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]

References

^ G. S. Hiers and F. D. Hager (1941). "Anisole". Organic Syntheses; Collected Volumes, vol. 1, p. 58.
^ 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
^ MSDS; its main hazard is its flammabiliy.[1]

External links

International Chemical Safety Card 1014
Pherobase pheromone database entry

[1] G. S. Hiers and F. D. Hager (1941). "Anisole". Organic Syntheses; Collected Volumes, vol. 1, p. 58.

[Ullmann-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; its main hazard is its flammabiliy.[1]

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