What Is Anisol?
Anisol, with the chemical formula C7H8O, is also known as methyl phenyl ether or anisole. This organic compound is recognized for its role as an insect pheromone and is characterized by its sweet aniseed scent.
For safe storage, anisol should be kept tightly sealed in a cool, well-ventilated area, away from direct sunlight, high temperatures, sparks, flames, and static electricity. It is advisable to avoid mixing with strong oxidizing agents. Anisol is classified as a hazardous and flammable substance.
Uses of Anisol
Anisol serves multiple purposes, including as an organic solvent, synthetic intermediate, anthelmintic, soap, industrial fragrance, and raw material for economical fragrances. Its ortho- and para-directive reactivity with acetic anhydride to produce p-methoxyacetophenone, a compound used for its floral fragrance or flavor, is particularly notable.
Furthermore, anisol can react with disulfuric dirine pentasulfide to produce Lawson’s reagent, a sulfidizing agent capable of replacing oxygen atoms with sulfur atoms in organic compounds, with the chemical formula [(CH3OC6H4)PS2]2.
Properties of Anisol
Anisol, a colorless liquid with a pleasant aroma, has a melting point of -37.5°C and boils at 155.5°C. It mixes well with ethanol and diethyl ether but is nearly insoluble in water. Its relatively low toxicity, with an LD50 in rats of 3,700 mg/kg, contrasts with its main hazard of flammability, highlighted by a low flash point of 52°C.
Due to the electron-donating methoxy group’s resonance effect, anisol exhibits a high electron density on the benzene ring, favoring ortho-para orientation in electrophilic reactions. The Hammett constants are -0.268 for the para effect and +0.115 for the meta effect.
Structure of Anisol
Anisol’s structure features a benzene ring with one hydrogen atom replaced by a methoxy group (–OCH3), combining a methyl group (-CH3) and a phenyl group (-C6H5) through an ether bond (-O-). Its molar mass is 108.14 g/mol, with a density of 0.995 g/mL.
Other Information on Anisol
1. Synthesis of Anisol
Anisol can be synthesized through the reaction of dimethyl sulfate with phenol in an alkaline solution, or via the Williamson synthesis involving sodium phenoxide and a methyl halide.
2. Reactions Involving Anisol
Besides forming p-methoxyacetophenone when reacted with acetic anhydride, anisol can engage in various chemical reactions, including the formation of π-complexes with metal carbonyls and the production of Lawson reagent through the reaction with diphosphorus pentasulfide (P4S10). The stability of anisol’s ether bond contrasts with the methyl group’s susceptibility to removal by hydroiodic acid, and its Birch reduction yields 1-methoxycyclohexa-1,4-dienes.