2-Methyl-1-pentanol, also known as isohexanol, is a branched-chain primary alcohol with the molecular formula C₆H₁₄O. Its systematic IUPAC name is 2-methylpentan-1-ol. The compound is a colorless liquid at room temperature and exhibits a characteristic alcoholic odor.
Chemical and Physical Properties
| Property | Value |
|---|---|
| Molecular formula | C₆H₁₄O |
| Molar mass | 102.18 g·mol⁻¹ |
| CAS Registry Number | 111-17-7 |
| Density | ≈ 0.822 g·cm⁻³ (20 °C) |
| Boiling point | ≈ 138 °C (at 1 atm) |
| Melting point | ≈ –73 °C |
| Refractive index (20 °C) | n_D ≈ 1.428 |
| Solubility | Miscible with water to a limited extent; soluble in most organic solvents (e.g., ethanol, ether, chloroform). |
| Flash point | ≈ 44 °C (closed cup) |
Structural Characteristics
- The carbon skeleton consists of a five‑carbon chain (pentane) bearing a methyl substituent at the second carbon atom and a hydroxyl group attached to the terminal (first) carbon.
- The structural formula can be represented as CH₃CH(CH₃)CH₂CH₂CH₂OH.
Synthesis
Industrial and laboratory preparations of 2‑methyl‑1‑pentanol typically involve:
- Hydration of 2‑methyl‑1‑pentene – catalytic addition of water (often using a phosphoric acid or sulfuric acid catalyst) to the corresponding alkene.
- Reduction of the corresponding aldehyde or ketone – for example, reduction of 2‑methyl‑pentanal with sodium borohydride (NaBH₄) or catalytic hydrogenation.
Applications
- Solvent: Utilized as a moderate‑polarity solvent in organic synthesis and in the formulation of coatings and inks.
- Intermediate: Serves as a building block for the synthesis of plasticizers, surfactants, and fragrance compounds.
- Research reagent: Employed in laboratory studies investigating the physicochemical behavior of branched alcohols.
Safety and Handling
- Flammability: Classified as a flammable liquid; appropriate fire‑safety measures (e.g., grounding, spark‑free environment) are required.
- Health hazards: Can cause irritation to skin, eyes, and respiratory tract upon contact or inhalation. Use of personal protective equipment (gloves, goggles, lab coat) and adequate ventilation is recommended.
- Environmental impact: Classified as hazardous to aquatic life with long‑term effects; dispose of waste according to local regulations.
Regulatory Information
- Listed under various chemical safety databases (e.g., OSHA, ECHA) with assigned hazard statements such as H225 (Highly flammable liquid) and H319 (Causes serious eye irritation).
Related Compounds
- 1‑Methyl‑1‑pentanol (iso‑amyl alcohol) – a structural isomer with the hydroxyl group on the same carbon as the methyl branch.
- 2‑Methyl‑2‑pentanol – a secondary alcohol isomer differing in the position of the hydroxyl group.
References
- CRC Handbook of Chemistry and Physics, 103rd Edition.
- National Center for Biotechnology Information (NCBI) PubChem Compound Summary for CID 2509.
- International Programme on Chemical Safety (IPCS) – Safety Data Sheets for 2‑Methyl‑1‑pentanol.
