Difference between revisions of "Methyl acetate"

Latest revision as of 11:29, 5 May 2018

Methyl acetate (or MeOAc) is an organic compound which is liquid at room temperature and widely used as a solvent. It has the chemical formula CH₃COOCH₃. Methyl acetate is the ester of acetic acid and methanol.

Properties

Chemical

Methyl acetate is carbonylated under high pressure (50 atm) and temperature (190 °C) to yield acetic anhydride:

CH₃CO₂CH₃ + CO → (CH₃CO)₂O

This reaction takes place in the presence of various catalysts.

Physical

Methyl acetate is a volatile colorless liquid, somewhat soluble in water (25%) and miscible with other organic solvents such as alcohols and ethers. Methyl acetate has a melting point of −98 °C. Its boiling point of 56.9 °C is very close to that of acetone (56.05 °C), making the separation of a mixture of the two compounds via fractional distillation complicated.

Availability

Methyl acetate is found in various paint thinners and sometimes in nail polishers. Fractional distillation is required to separate it.

Methyl acetate is sometimes found mixed with ethyl acetate, in certain (poly)urethane strippers.

Preparation

Methyl acetate can be made via Fischer esterification, between anhydrous methanol and glacial acetic acid. A catalyst such as sulfuric acid is used, though iron(III) sulfate can also be used. The process takes place under reflux. After the reaction has ended, leftover acetic acid is neutralized using sodium bicarbonate. The crude methyl acetate is extracted using a separatory funnel and dried using calcium chloride. If required, the methyl acetate can be further purified via fractionated distillation.

For better yield, acetic anhydride can be used instead of acetic acid.

Projects

• Organic extractions
• Acetic anhydride synthesis

Handling

Safety

Methyl acetate is flammable. While it is considered a mild skin irritant, methyl acetate poses little toxicity.

Storage

Methyl acetate should be stored in closed bottles, and kept away from moisture, acidic vapors and bases. Due to its relative low boiling point, it's best to keep it in a cool place, especially during summer.

Disposal

Methyl acetate can be safely burned, preferably outside. Hydrolysis yields acetic acid and methanol which can either be recovered or destroyed.

References

Relevant Sciencemadness threads

• methyl acetate
• methyl acetate from AgOOCH3