Methyl Acetate IUPAC Name
Methyl acetate is an ester known as MeOAc or methyl ester of acetic acid. The IUPAC name of methyl acetate is methyl ethanoate. This organic compound remains as a colorless liquid or vapor. However, the compound is toxic and only used as a solvent occasionally. It is weakly polar and does not readily dissolve in water. When heated its solubility in water increases, considerably. Methyl acetate is lipophilic and dissolves with fats. Methyl ethanoate is unstable in the presence of strong aqueous acids, or bases. The compound hydrolyzes in presence of strong acids and bases to give methanol and acetic acid. The conversion to its components is a first-order reaction of an ester concerning acid.
Methyl Acetate Structure
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Methyl Acetate Formula
Methyl acetate molecular weight: 74.08 g/mol
Methyl acetate chemical formula: C3H6O2
It appears as a clear colorless liquid with a pleasant fruity fragrance. It is volatile.
Methyl acetate boiling point: 56.80C
Methyl acetate melting point: -98.0oC
It is soluble in water. Solubility: 250C
It is also miscible with alcohol and ether, especially in ethyl ether and ethanol.
Methyl acetate density: 0.9342 g/cu cm at 200C
Methyl acetate vapor pressure: 216.2 mm Hg at 250C
Refractive index: 1.3614 at 200C
It decomposes upon heating or contact with air, bases, strong oxidizers, UV light and emits acrid smoke and toxic fumes when heated.
Methyl Acetate Uses
Methyl acetate is used as a flavoring agent in the form of a food additive. It is also used as a flavoring agent in various alcoholic beverages.
In the food industry, it is used in baking goods, gelatins, puddings, frozen dairy, and baked goods.
It is used as a solvent for many resins and oils such as nitrocellulose, acetyl cellulose, etc.
In industries, it is used as an adhesive, lubricants and lubricant additives, pigments, paint and coating additives, etc.
It is also used in electrical and electronic products, furnishing and cleaning products, floor coverings, ink, toner, and colorant products, etc.
It is used as a solvent for cleaning and degreasing purposes.
Production of Methyl Acetate
Methyl acetate can be prepared by the esterification reaction acetic acid with methanol at elevated temperature in presence of an esterification catalyst which can be strong acids like sulfuric acid.
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This reaction is done by the process of reactive distillation, where the separation of products of reaction does not need a separate distillation step.
The process includes constant feeding of methanol, acetic acid, and entrainer to the reaction kettle.
Here, reaction products are constantly removed from the reactive zone to increase the conversion. This production process was made popular by Eastman kodak.
For industrial purposes, methyl acetate is produced by the carbonylation of methanol as a byproduct of the acetic acid synthesis.
Hydrolysis of Methyl Acetate
Acid Hydrolysis of Methyl Acetate:
Methyl ethanoate or ethyl acetate, being an ester, hydrolysis to produce acetic acid and methyl alcohol when it is heated in the presence of an acid. The acid acts as a catalyst. The water molecule provides the -OH group to convert the carbonyl group present to a carboxyl group.
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Basic Hydrolysis of Methyl Acetate:
The basic hydrolysis of methyl acetate is also known as the saponification reaction of esters. In the reaction, when methyl acetate is heated in presence of a strong base such as NaOH it breaks down to give sodium salt of acetate ion and methyl alcohol.
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FAQs on Methyl Acetate
1. What is methyl acetate and what are its chemical formula and structure?
Methyl acetate, also known by its IUPAC name methyl ethanoate, is an ester. Its chemical formula is C₃H₆O₂. The structure consists of an acetate group (CH₃COO-) bonded to a methyl group (-CH₃), featuring an ester (-COO-) as its functional group.
2. What are the main physical properties of methyl acetate?
Methyl acetate is a clear, colourless, and highly flammable liquid known for its pleasant, fruity fragrance. Its key physical properties include:
- Boiling Point: 56.8°C
- Melting Point: -98.0°C
- Solubility: It is slightly soluble in water but is miscible with most organic solvents like alcohol and ether.
- Volatility: It is a highly volatile compound.
3. What are some important real-world uses of methyl acetate?
Methyl acetate is a versatile compound with several industrial and commercial applications. It is commonly used as:
- A solvent for various resins, oils, paints, and lacquers.
- A flavouring agent in the food industry for items like baked goods, puddings, and gelatins.
- An ingredient in adhesives, cleaning products, and lubricants.
- A chemical intermediate for synthesizing other organic compounds.
4. How is methyl acetate typically prepared in a laboratory?
The most common laboratory method for preparing methyl acetate is the Fischer esterification reaction. This process involves heating a mixture of acetic acid (CH₃COOH) and methanol (CH₃OH) in the presence of a strong acid catalyst, such as concentrated sulfuric acid (H₂SO₄). The reaction is reversible and produces methyl acetate and water.
5. Is methyl acetate harmful to humans?
Yes, methyl acetate poses health hazards. It is highly flammable in both liquid and vapour forms. Inhaling its vapours can cause headaches, dizziness, and irritation to the respiratory tract. Direct contact with the liquid can irritate the skin and eyes. Therefore, it must be handled with appropriate safety precautions in a well-ventilated area.
6. How does the hydrolysis of methyl acetate differ in acidic versus basic conditions?
The hydrolysis of methyl acetate breaks it down into acetic acid and methanol, but the mechanism and final products depend on the pH:
- Acidic Hydrolysis: In the presence of an acid catalyst and water, the reaction is reversible. It breaks the ester down into its constituent parts: acetic acid and methanol.
- Basic Hydrolysis (Saponification): In the presence of a strong base like NaOH, the reaction is irreversible. It produces methanol and the salt of the carboxylic acid, which is sodium acetate (CH₃COONa), not acetic acid.
7. How can one distinguish between methyl acetate and the similar compound ethyl acetate?
While methyl acetate and ethyl acetate are both colourless esters with fruity smells, they can be distinguished using the iodoform test. First, each ester is hydrolysed with a base (like NaOH) to produce its corresponding alcohol (methanol from methyl acetate, ethanol from ethyl acetate). When the hydrolysed solution containing ethanol is treated with iodine, it forms a distinctive yellow precipitate of iodoform (CHI₃). The solution from hydrolysed methyl acetate, containing methanol, will not produce this precipitate.
8. Is methyl acetate considered an acid or a base?
Methyl acetate is functionally neutral; it is neither an acid nor a base. As an ester, it does not typically donate or accept protons like Brønsted-Lowry acids and bases do. Although it reacts in the presence of strong acids or bases during hydrolysis, the molecule itself does not have inherent acidic or basic properties in an aqueous solution.
9. Why is methyl acetate sometimes confused with acetone, and what is the key difference?
Methyl acetate and acetone are often confused because both are common, volatile organic solvents. However, they are chemically distinct. The primary difference lies in their functional groups:
- Methyl Acetate is an ester (CH₃COOCH₃), containing two oxygen atoms in its core structure.
- Acetone is a ketone (CH₃COCH₃), containing only one oxygen atom double-bonded to a central carbon.
