1,5-Hexadiene (CAS 592-42-7) is a fundamental organic compound with a distinct set of properties that make it relevant across various chemical industries. This article provides an in-depth look at its physical characteristics, common synthesis pathways, and crucial safety considerations for its handling and storage. Understanding these aspects is vital for anyone working with this versatile chemical intermediate.

Physically, 1,5-Hexadiene is described as a colorless, volatile liquid. Its chemical formula, C6H10, indicates a hydrocarbon structure featuring two double bonds. Key physical properties include a melting point of -141 °C and a boiling point of approximately 60 °C. Its density is around 0.692 g/mL at 25 °C, and it has a refractive index of 1.404 at 20 °C. The compound is reported to be soluble in water, though to a limited extent (0.17 g/L). Its powerful, diffusive odor is noted, though it is of poor tenacity.

The 1,5-Hexadiene synthesis is primarily achieved through two main routes. Commercially, it is often produced via the ethenolysis of 1,5-cyclooctadiene, a process that employs a catalyst based on Re2O7 on alumina. For laboratory-scale preparations, the reductive coupling of allyl chloride using magnesium serves as an effective method. The availability of reliable 1,5-Hexadiene synthesis methods ensures its accessibility for research and industrial applications.

Safety is a paramount concern when dealing with any chemical substance, and 1,5-Hexadiene is no exception. It is classified as highly flammable, with a low flash point of -17 °F. Hazard statements associated with it include H225 (Highly flammable liquid and vapour), H302 (Harmful if swallowed), H305 (May be harmful if swallowed and enters airways), H315 (Causes skin irritation), H319 (Causes serious eye irritation), and H335 (May cause respiratory irritation). Precautionary measures such as keeping it away from heat, sparks, and open flames, ensuring proper ventilation, and using appropriate personal protective equipment are essential. Store it in a cool, dry place in well-sealed containers, ideally under nitrogen to maintain its quality and prevent degradation.

The consistent demand for high-purity 1,5-Hexadiene stems from its utility as a chemical intermediate and its role in polymerization. Its applications in organic synthesis are diverse, serving as a building block for more complex molecules. The ability to understand and manage its properties and hazards is key to its safe and effective use in the chemical industry.