Cyclooctane
Cyclooctane is a cycloalkane and saturated cyclic hydrocarbon with the molecular formula C₈H₁₆, consisting of eight carbon atoms arranged in a ring, each bonded to two hydrogen atoms. It appears as a colorless liquid at room temperature, with a melting point of 14.8 °C, a boiling point of 151 °C, a density of 0.834 g/mL at 25 °C, and limited solubility in water (approximately 0.008 g/L).[1][2][3] In terms of molecular structure, cyclooctane exhibits multiple conformations due to its medium-sized ring, with the boat-chair (BC) form identified as the lowest-energy and most stable configuration in the gas phase, featuring average C–C bond lengths of 1.540 Å and C–C–C bond angles of 116.8°. This conformational flexibility distinguishes it from smaller cycloalkanes like cyclohexane, which prefer a chair form, and contributes to its unique physical properties compared to linear alkanes of similar molecular weight, such as n-octane.[4] Cyclooctane finds applications primarily as a chemically inert solvent in organic synthesis and as a synthetic intermediate for producing derivatives like cyclooctanone, which is used in further chemical manufacturing. It is also employed in homogeneous catalysis precursors and pharmaceutical synthesis, leveraging its stability and nonpolar nature. Safety considerations include its flammability, with a flash point of 28 °C, necessitating proper handling in laboratory and industrial settings.[5][2][6]Properties
Physical properties
Cyclooctane has the molecular formula C₈H₁₆ and a molar mass of 112.21 g/mol.[7] It appears as a colorless liquid at room temperature with a camphoraceous odor.[8][9] The compound exhibits a melting point of 14.7 °C and a boiling point of 151 °C at standard pressure.[10] Its density is 0.834 g/cm³ at 25 °C, while the refractive index is 1.458 (n²⁰/D).[8] Cyclooctane is insoluble in water, with a solubility of 7.9 mg/L at 25 °C, but it is miscible with common organic solvents such as ethanol and diethyl ether.[11][3] Additional bulk properties include a kinematic viscosity of 1.996 mm²/s at 40 °C and a surface tension of 30 mN/m at 20 °C.[12][13] Compared to smaller cycloalkanes like cyclohexane, the larger ring size of cyclooctane contributes to its liquidity at ambient conditions despite a slightly higher melting point.[10]| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 14.7 °C | - | PubChem |
| Boiling point | 151 °C | 987 hPa | Sigma-Aldrich |
| Density | 0.834 g/cm³ | 25 °C | Sigma-Aldrich |
| Refractive index | 1.458 | 20 °C (D line) | Sigma-Aldrich |
| Water solubility | 7.9 mg/L | 25 °C | Good Scents Co. |
| Kinematic viscosity | 1.996 mm²/s | 40 °C | Sigma-Aldrich |
| Surface tension | 30 mN/m | 20 °C | Cheméo |