Cinnamic acid is a white crystalline organic compound found widely in nature and frequently synthesized for industrial purposes. Chemically known as 3-phenylpropenoic acid, this unsaturated carboxylic acid features a faint, honey-like odor. It is a precursor for many other compounds, making it valuable in various manufacturing processes. Understanding its safety profile, especially its flammability, is important for handling and storage.
Flammability and Hazard Classification
Cinnamic acid is a solid powder at room temperature, which significantly reduces its flammability risk compared to liquids. Solid organic acids generally require more energy to ignite. The substance has a flash point of 100°C (212°F), which is the temperature at which it produces enough vapor to ignite temporarily when an ignition source is applied. This relatively high flash point indicates it is not considered a highly flammable material under standard conditions.
Its official classification under the National Fire Protection Association (NFPA) 704 system is low, with a flammability rating of 1. This rating signifies that the material requires considerable preheating before ignition can occur. The primary fire concern is not the solid bulk material itself, but the risk associated with fine organic powders. When cinnamic acid is processed into a fine dust and dispersed in the air, it can form an explosive mixture. This potential for a dust explosion is a common hazard for many finely divided organic solids.
Essential Safety and Storage Practices
The primary safety measure when handling cinnamic acid involves strict dust control to mitigate the potential for a dust explosion. Personnel should avoid generating dust clouds, especially in confined spaces, and utilize appropriate exhaust ventilation during processing. Even empty containers may harbor residual dust that could pose an explosion risk if disturbed near an ignition source. Personal protective equipment, including safety glasses and gloves, should be worn to prevent irritation, as the compound is classified as an irritant.
Proper storage conditions help maintain the compound’s stability and prevent accidental reactions. Cinnamic acid should be kept in a cool, dry, and well-ventilated location, with the container tightly sealed when not in use. It is incompatible with strong oxidizing agents, and contact must be avoided to prevent violent reactions. In the event of a fire, standard extinguishing media such as water spray, alcohol-resistant foam, dry chemical, or carbon dioxide are effective.
Where Cinnamic Acid is Found
Cinnamic acid occurs naturally in various plants, serving as a central intermediate in the biosynthesis of many natural products. It is a component of spices such as cinnamon and can be found in balsams like storax. Natural sources also include shea butter, certain fruits, vegetables, and beverages. The compound and its derivatives are present in citrus fruits, grapes, tea, cocoa, and spinach.
Commercially, cinnamic acid is utilized across several industries due to its aromatic and chemical properties. It is a common ingredient in the flavor and fragrance sectors, often used as a precursor to create esters for perfumes. The cosmetic industry incorporates it as a UV absorber and antioxidant. It also serves as a precursor in pharmaceutical synthesis and is a building block for producing the artificial sweetener aspartame.