1. Chemical Structure and Properties
Molecular Formula: C₄H₉OH
Structural Formula: CH₃CH₂CH₂CH₂OH
A primary aliphatic alcohol with a four-carbon chain and a hydroxyl (-OH) group at the terminal carbon.
Physical Properties:
Appearance: Clear, colorless liquid with a characteristic alcoholic odor.
Boiling Point: 117.7°C; Density: 0.81 g/cm³; Vapor Pressure: 6.7 mmHg at 25°C.
Solubility: Partially soluble in water (7.7 g/100 mL at 20°C); fully miscible with ethanol, ether, and most organic solvents.
Chemical Properties:
Reactivity:
Oxidizes to butyraldehyde and further to butyric acid under strong conditions.
Forms esters (e.g., n-butyl acetate) and ethers via hydroxyl group reactions.
Flammability: Combustible (flash point: 35°C; autoignition temperature: 343°C).
2. Industrial Applications
Solvent Industry:
Coatings & Inks: Key solvent for resins, lacquers, and printing inks due to moderate evaporation rate.
Cleaning Agents: Effective in degreasing metals and electronics.
Chemical Synthesis:
Intermediate: Produces plasticizers (e.g., dioctyl phthalate), pharmaceuticals, and agrochemicals.
Ester Production: n-Butyl acetate (widely used in paints) is synthesized via esterification with acetic acid.
Fuel Additives:
Biofuel Blending: Enhances octane ratings and reduces emissions in gasoline blends.
Personal Care:
Cosmetic Formulations: Solvent for fragrances and stabilizer in lotions.
3. Safety and Toxicology
Health Hazards:
Acute Exposure:
Inhalation (≥50 ppm): Irritates eyes, nose, and throat; CNS depression at high concentrations (TLV-TWA: 20 ppm).
Skin Contact: Causes defatting and dermatitis (rabbit skin LD₅₀: >2,000 mg/kg).
Ingestion: Moderately toxic (oral LD₅₀ rat: 790 mg/kg); induces gastrointestinal distress.
Chronic Effects:
Liver/Kidney Toxicity: Observed in animal studies with prolonged high-dose exposure.
Reproductive Toxicity: Limited evidence of developmental risks (EU CLP: Not classified).
Protection Measures:
PPE: Nitrile gloves, vapor respirators, and explosion-proof equipment.
Storage: Fireproof containers in cool, ventilated areas away from oxidizers.
4. Environmental and Regulatory Compliance
Environmental Impact:
Biodegradability: Readily biodegradable (OECD 301F: >80% in 28 days).
Aquatic Toxicity: LC₅₀ (fish, 96h): ~1,000 mg/L; low bioaccumulation (log Kow: 0.88).
VOC Emissions: Classified as a volatile organic compound (VOC) in coatings and adhesives.
Regulatory Frameworks:
EU:
CLP Regulation: Classified as Flam. Liq. 3 (H226), Eye Irrit. 2 (H319).
REACH: Registered with no SVHC listing.
USA:
EPA: Regulated under Clean Air Act for VOC emissions; listed on TSCA Inventory.
China:
GB 13690-2009: Classified as Hazardous Chemical (Class 3.3).
Waste Management:
Incinerate with VOC abatement; wastewater treatment via biodegradation.
5. Case Studies and Application Insights
Case 1: Sustainable Paint Formulation (AkzoNobel, 2022):
Challenge: Replace VOC content in architectural paints.
Solution: Replaced 30% of n-butyl alcohol with bio-based 2-butanol derived from corn starch.
Result: Achieved 25% lower VOC emissions while maintaining drying performance (ASTM D5895).
Case 2: Pharmaceutical Synthesis (Pfizer, 2021):
Process: Used n-butyl alcohol as a reaction medium for synthesizing antiviral drug intermediates.
Efficiency: Improved yield by 15% vs. ethanol-based systems due to higher boiling point.
Comparative Analysis:
n-Butanol vs. Ethanol:
Pros: Higher solvency for non-polar compounds; slower evaporation for better film formation.
Cons: Higher toxicity and flammability risk.
n-Butanol vs. Isobutanol:
Pros: Lower cost and broader industrial adoption.
Cons: Isobutanol offers better water tolerance in fuel blends.