CH3COCOCH3

CH3COCOCH3 is the chemical diacetyl, also known as butane-2,3-dione. Its molecular formula is C4H6O2. It is a symmetric diketone in which two acetyl groups are joined by a single bond between their carbonyl carbons (structure: CH3–CO–CO–CH3). It is a colorless to pale yellow liquid with a characteristic buttery odor.

Diacetyl occurs naturally in dairy products and is produced by certain lactic acid bacteria during fermentation. It is also formed during the roasting of coffee and in some beer fermentations. Industrially, diacetyl is produced and supplied as a flavoring agent for use in foods and beverages.

Uses of diacetyl are primarily culinary. It provides butter-like flavors in products such as popcorn, baked goods, and dairy items. It is widely used as a food flavoring agent and is also employed in some fragrance applications. In the United States, diacetyl is approved as a flavoring agent and is generally recognized as safe (GRAS) when used in accordance with good manufacturing practice.

Safety and regulatory aspects: Inhalation exposure to diacetyl has been linked to serious respiratory effects, including bronchiolitis obliterans, particularly in occupational settings such as flavoring manufacture and popcorn production. Consequently, workplace exposure controls and safety practices are advised to minimize inhalation risk. By contrast, consumer exposure through food is typically governed by established flavoring use guidelines and regulatory oversight, and diacetyl is used at levels consistent with flavor industry standards.