What Is Hexanal?
Hexanal, an organic compound, is a chained aliphatic aldehyde with the chemical formula C6H12O and CAS number 66-25-1.
It has a molecular weight of 100.16, a melting point of -56 °C, and a boiling point of 131 °C. At room temperature, hexanal is a clear, colorless liquid with a distinct odor reminiscent of green leaves and manure. It is the source of the characteristic foul odor in soybeans and grass. Soluble in ethanol and acetone, hexanal is insoluble in water, with a density of 0.8335 g/cm³.
Uses of Hexanal
Hexanal has several applications, including the following:
- Flavoring agent in alcoholic beverages, butter, and cosmetics
- Component in dyes
- Raw material for plasticizers and synthetic resins
- Used in pesticide production
It is also utilized to produce 1-hexanol, a plasticizer raw material, via hydrogenation. Despite its foul odor, hexanal is an ingredient in fragrances, imparting green flavors to fruit flavors and fresh notes to dairy and rum flavors.
Principle of Hexanal
Hexanal’s synthesis and chemical properties are explained as follows:
1. Synthesis of Hexanal
In living organisms, hexanal is produced by the oxidation of fatty acids. In soybeans, for example, linoleic acid is converted to hexanal via lipoxygenase and hydroperoxide lyase. Industrially, it’s obtained through the hydroformylation of 1-pentene.
2. Chemical Properties of Hexanal
Hexanal is prone to oxidation and polymerization, especially in acidic conditions, due to its formyl group (-CHO). In soybeans, it oxidizes to caproic acid, and in synthetic chemistry, it is used in Wittig and Aldol reactions. Despite its reactivity, hexanal is stable under proper storage and handling.
3. Hexanal in the Real World
Hexanal forms in foods during cooking due to lipid peroxidation, contributing to the deteriorating odor in products like instant noodles and coffee milk. It also appears in juices and olive oil. With a low flash point of 32 °C, it is highly flammable and must be stored away from ignition sources. It is subject to various safety regulations due to its hazardous nature.
Types of Hexanal
Hexanal is available in forms for industrial use and as research reagents. Industrial products are typically sold in large capacities, such as drums and oil cans, for use in organic synthesis and fragrance production. Research reagents are available in various smaller volumes for laboratory use. Some are stored at room temperature, while others require refrigeration. Given its high flammability, caution is advised during storage and transportation.