4-Methoxybutan-2-one

This compound is typically encountered as a clear, colorless liquid with a characteristic sweet, ethereal odor reminiscent of ketones and ethers. Its molecular formula is C5H10O2, corresponding to a molecular weight of 102.13. The boiling point is approximately 135–138 °C at atmospheric pressure, with a calculated density near 0.96 g/cm³ at 20 °C. It is miscible with common organic solvents including ethanol, acetone, and diethyl ether, and shows moderate solubility in water due to the polar ether and ketone functionalities. The molecule contains both a ketone carbonyl and an ether linkage, making it susceptible to nucleophilic addition at the carbonyl and potentially prone to enolization under basic conditions. Storage in tightly sealed containers protected from light and moisture at ambient temperature is generally adequate, though cool storage is recommended for prolonged periods. Contact with strong oxidizing agents and strong bases should be avoided.

4-Methoxybutan-2-one is a linear aliphatic compound combining a ketone carbonyl at the 2-position with a methoxy ether at the 4-position, separated by a two-carbon methylene chain. This structure creates a β-alkoxy ketone, where the ether oxygen can influence the reactivity of the carbonyl through inductive effects and potential chelation interactions. The ketone functionality provides an electrophilic site for nucleophilic addition and condensation reactions, while the α-methylene protons exhibit enhanced acidity due to conjugation with the carbonyl. The methoxy group contributes hydrophilicity and can participate in hydrogen bonding as an acceptor. This compact, bifunctional architecture makes the compound a versatile intermediate in organic synthesis, where the ketone can undergo transformations typical of carbonyl compounds while the ether remains stable under most conditions or can be cleaved when desired.

Organic Synthesis Intermediate
This β-alkoxy ketone is employed as a building block in the synthesis of more complex molecules, including heterocycles and natural product analogs. The ketone can undergo aldol condensations, Michael additions, and alkylation reactions at the αposition to introduce additional carbon chains and functional groups. The methoxy group can serve as a protecting group for a hydroxyl or be converted to other functionalities through ether cleavage.

Pharmaceutical Intermediate
In medicinal chemistry, 4-methoxybutan-2-one is used as a precursor for synthesizing compounds with potential activity against metabolic disorders and inflammation. The ketone can be transformed into amines via reductive amination or into alcohols via reduction, providing access to diverse pharmacophores. The ether oxygen can influence solubility and pharmacokinetic properties of the final drug candidates.

Flavor and Fragrance Ingredient
Ketones with ether functionalities are known for their contribution to fruity and buttery aroma profiles. This compound and its derivatives are investigated as flavoring agents, imparting sweet, creamy notes to food products and beverages. Its volatility and stability under processing conditions make it suitable for use in baked goods and confectionery applications.

Building Block for Fine Chemicals
As a versatile synthetic intermediate, 4-methoxybutan-2-one participates in diverse transformations including Grignard additions, Wittig olefinations, and condensation with amines to form enamines. The resulting products find applications in the synthesis of agrochemicals, specialty chemicals, and functional materials where the combination of ketone and ether functionalities provides opportunities for controlled molecular elaboration.