1-Butanol
Properties
| State | Liquid at room temperature |
| Color | Colorless |
| Solubility | Slightly soluble in water (7.7 g/100 mL at 25 °C) |
| Melting Point | -89.8 °C |
| Boiling Point | 117.7 °C |
About 1-Butanol
1-Butanol is the four-carbon primary alcohol where the homologous series finally breaks with water. Methanol, ethanol, and 1-propanol are all infinitely miscible — the OH hydrogen-bonds well enough to keep the small alkyl tails dissolved — but at four carbons the hydrophobic chain wins, and butanol drops to 7.7 g/100 mL solubility at 25 °C. That single fact is why butanol is the standard textbook example of the polarity-versus-chain-length trade-off in organic chemistry. Molar mass is 74.121 g/mol, boiling point 117.7 °C, and the smell is the rancid, fruity-fusel note that gives unrefined spirits their off-character: butanol is one of the major fusel oils produced as a yeast byproduct during ethanol fermentation, separated out during distillation. In coatings and inks, butanol's combination of moderate volatility (slow enough to give good film formation, fast enough not to linger) and high solvent power for resins makes it the workhorse alcohol in nitrocellulose lacquers, alkyd enamels, and automotive refinish. The biofuel push of the 2010s revisited butanol seriously: the ABE (acetone-butanol-ethanol) fermentation by Clostridium acetobutylicum predates ethanol fuels by decades, and butanol's higher energy density (~30% more than ethanol per gallon) and gasoline-like miscibility let it run in unmodified spark-ignition engines, though fermentation yields lag ethanol enough that the economics still don't fully close.
Where you'll encounter it
If you've ever opened a can of nitrocellulose lacquer or thinned an alkyd enamel, the slightly sweet alcohol smell is mostly butanol. In an organic teaching lab, butanol shows up as the upper phase in liquid-liquid extractions where ethyl acetate would be too lipophilic and ethanol would just dissolve in the aqueous layer — useful for pulling moderately polar natural products. In a process plant, butanol is also the precursor for butyl acrylate (the soft monomer in nearly every pressure-sensitive adhesive and exterior latex paint) and butyl acetate (the smell of fingernail polish), so a few of these molecules pass through butanol on their way to your front door.
Common Uses
- Solvent for nitrocellulose lacquers, alkyd enamels, and automotive coatings
- Precursor for butyl acrylate (latex paint and PSA adhesives) and butyl acetate
- Drop-in biofuel candidate compatible with spark-ignition engines
- Plasticizer feedstock for dibutyl phthalate and dibutyl sebacate
- Extraction solvent in pharmaceutical and natural-product chemistry
Safety Information
Flammable liquid (flash point 35 °C). OSHA PEL 100 ppm (300 mg/m³) as an 8-hr TWA, ACGIH TLV 20 ppm as a ceiling value because of the eye and upper-respiratory irritation. Causes mild eye irritation and CNS depression at high vapor concentrations; less acutely toxic than methanol and not a metabolic poison. Use with adequate ventilation, splash goggles, and nitrile or butyl rubber gloves; bond and ground containers when transferring.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.