1-Octanol
1-Octanol, also known as n-octanol or octan-1-ol, is a straight-chain primary alcohol with the molecular formula C₈H₁₇OH. It consists of an eight-carbon unbranched alkyl chain terminated by a hydroxyl group and appears as a clear, colorless, oily liquid with a mild, characteristic odor. This fatty alcohol is sparingly soluble in water (0.54 g/L at 20°C) but miscible with organic solvents such as ethanol and ether.[1] Key physical properties of 1-octanol include a boiling point of 194–195°C, a melting point of −15.5°C, and a density of 0.826 g/cm³ at 25°C. It is combustible with a flash point of 81°C and exhibits low vapor pressure, making it relatively stable under normal conditions. Industrially, 1-octanol is primarily produced by the hydrogenation of octanal, which is obtained through the hydroformylation (oxo process) of 1-heptene derived from petrochemical sources; it can also be sourced from the reduction of octanoic acid in natural fats like coconut oil.[1][2] 1-Octanol finds wide application as a chemical intermediate and solvent in various industries. It is used in the production of esters, such as octyl acetate for fragrances and flavors, and serves as a component in perfumes, cosmetics, inks, paints, and plasticizers. Additionally, it acts as a defoaming agent, a flavoring agent in food (e.g., imparting orange-like notes), and a precursor in pesticide formulations. In research, it models hydrophobic environments in biological systems, such as in the octanol-water partition coefficient (log P ≈ 3.0) for assessing drug solubility.[1] Regarding safety, 1-octanol is irritating to the skin and eyes, and may cause respiratory tract irritation upon direct contact or inhalation of vapors, but it poses low acute toxicity with an oral LD₅₀ in rats exceeding 5 g/kg. It is not classified as a specific target organ toxicant or aspiration hazard under normal use, though proper ventilation and protective equipment are recommended during handling. Environmentally, it is biodegradable but can be harmful to aquatic life (LC₅₀ for fish ≈ 11–14 mg/L, 96 h).[1][3][4]Chemical Identity
Structure and Formula
1-Octanol is an organic compound classified as a straight-chain primary alcohol, featuring a hydroxyl group (-OH) attached to the first carbon of an eight-carbon alkane chain. Its molecular formula is C₈H₁₈O, reflecting the composition of eight carbon atoms, eighteen hydrogen atoms, and one oxygen atom.[1] This formula can also be represented as C₈H₁₇OH to emphasize the alcohol functional group.[5] The structural formula of 1-octanol is CH₃(CH₂)₆CH₂OH, depicting a linear hydrocarbon chain where the terminal methyl group (CH₃-) is connected through six methylene groups (-CH₂-) to the hydroxymethyl group (-CH₂OH).[1] This unbranched configuration contributes to its role as a fatty alcohol, commonly found in natural lipid sources.[1] The IUPAC name for this compound is octan-1-ol, systematically indicating the position of the hydroxyl group on the octane parent chain.[5] Key identifiers for 1-octanol include a molecular weight of 130.23 g/mol, calculated from its atomic composition.[1] The Chemical Abstracts Service (CAS) registry number is 111-87-5, a unique identifier used in chemical databases and regulatory contexts.[5] In computational chemistry, it is represented by the SMILES notation CCCCCCCCO, which linearly encodes the carbon chain and terminal hydroxyl group for structure generation and analysis.[1]Nomenclature and Synonyms
1-Octanol, systematically named octan-1-ol according to IUPAC nomenclature, is a straight-chain primary alcohol with the hydroxy group attached to the terminal carbon of an eight-carbon saturated hydrocarbon chain.[1] Common synonyms include n-octanol, octyl alcohol, and capryl alcohol (also known as caprylic alcohol), which reflect its historical and industrial designations.[1][6] In early 20th-century chemical literature, it was frequently referred to as primary octyl alcohol to distinguish it from branched isomers like 2-ethylhexanol, which shared the generic "octyl alcohol" name.[1] As a saturated fatty alcohol, 1-octanol belongs to the class of primary alcohols derived from natural fats and oils, characterized by a linear alkyl chain and a single hydroxyl group at the end.[1][7] It is assigned the European Community (EC) number 203-917-6 in the EC Inventory for regulatory purposes.[1]Physical Properties
Appearance and Sensory Characteristics
1-Octanol appears as a clear, colorless liquid at standard room temperature conditions, exhibiting an oily texture due to its long hydrocarbon chain attached to the alcohol functional group. This viscous quality contributes to its tactile sensation as a slippery, non-greasy fluid that remains stable and non-volatile under ambient conditions.[1] The compound possesses a distinctive pungent, aromatic odor, commonly characterized as waxy and fatty with undertones of citrus, green, and floral notes such as orange rose or lemon-like scents. Sensory evaluations in fragrance contexts further describe it as sharp, aldehydic, and occasionally mushroom-like, reflecting its role in perfumery and essential oils.[1][8] In terms of taste, 1-octanol imparts an oily, waxy profile with fruity and herbaceous nuances, including mild bitterness akin to bitter almond in certain flavor applications.[1][8]Thermodynamic Properties
1-Octanol, a primary alcohol with an eight-carbon chain, displays thermodynamic properties that govern its phase transitions, thermal stability, and rheological behavior under standard conditions. These characteristics are influenced by its molecular structure, including the polar hydroxyl group and nonpolar alkyl chain, which contribute to intermolecular forces such as hydrogen bonding and London dispersion forces. Understanding these properties is essential for predicting its performance in processes involving heating, evaporation, or fluid dynamics. Key thermodynamic properties of 1-octanol include its density, which is 0.824 g/cm³ at 20°C, indicating a relatively low mass per unit volume typical for liquid alcohols of this chain length.[9] The melting point is −16 °C, allowing it to remain liquid at ambient temperatures above this threshold.[10] Its boiling point is 195 °C at 1 atm, reflecting strong intermolecular attractions that require significant energy input for vaporization.[1]| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 81 °C | Closed cup | https://www.fishersci.com/shop/products/1-octanol-certified-acs-fisher-chemical/A402500 |
| Autoignition temperature | 245 °C | - | http://mubychem.com/octanol-manufacturers-octylalcohol.html |
| Viscosity | 7.36 mPa·s | 20 °C | https://www.chemeo.com/cid/49-458-0/1-Octanol |
| Refractive index | 1.429 | 20 °C | https://www.sigmaaldrich.com/US/en/product/mm/820931 |
| Heat of vaporization | Approximately 52 kJ/mol | Near boiling point | https://webbook.nist.gov/cgi/cbook.cgi?ID=C111875 |