Undecane is a saturated straight‑chain hydrocarbon belonging to the alkane series, with the molecular formula C₁₁H₂₄. It consists of eleven carbon atoms linked exclusively by single bonds, terminated by hydrogen atoms, and is thus a member of the homologous series of alkanes.
Physical properties
| Property | Value |
|---|---|
| Appearance | Colorless liquid |
| Density (20 °C) | ~0.766 g cm⁻³ |
| Boiling point | 196 °C (384 °F) |
| Melting point | –30 °C (–22 °F) |
| Vapor pressure (20 °C) | ~0.12 kPa |
| Solubility | Practically insoluble in water; miscible with most organic solvents |
Isomerism
While the term “undecane” most commonly refers to the n‑undecane (linear) isomer, the chemical formula C₁₁H₂₄ permits a large number of branched isomers (over 150, depending on classification criteria). These structural isomers differ in the arrangement of the carbon skeleton but share the same molecular formula and general properties typical of alkanes.
Chemical behavior
Undecane is chemically inert under standard conditions, characteristic of alkanes. It undergoes combustion in the presence of oxygen to yield carbon dioxide, water, and heat:
C₁₁H₂₄ + 17 O₂ → 11 CO₂ + 12 H₂O + heat
Under catalytic conditions, undecane can be cracked to produce shorter‑chain alkanes and alkenes, a process employed in petroleum refining.
Applications
Undecane is used primarily as a reference standard in analytical chemistry (e.g., gas chromatography) due to its well‑characterized physical properties. It also serves as a model compound in studies of hydrocarbon behavior, phase equilibria, and fuel properties.
Safety
Undecane is flammable and should be handled with appropriate fire‑prevention measures. It may cause irritation to skin and eyes upon contact; inhalation of vapors in high concentrations can lead to respiratory irritation. Standard laboratory safety protocols, including use of gloves, goggles, and adequate ventilation, are recommended.
Occurrence
Undecane is not commonly found in significant quantities in nature but can be produced as a component of petroleum distillates and as a minor constituent of certain essential oils and plant extracts in trace amounts.
