1. Chemical Structure and Properties
Molecular Formula: C₄H₈O₂
Structural Formula:
CH₃COOCH₂CH₃
A carboxylic acid ester formed by the esterification of acetic acid with ethanol.
Physical Properties:
Appearance: Clear, colorless liquid with a fruity, pleasant odor.
Boiling Point: 77.1°C
Density: 0.894–0.898 g/cm³
Vapor Pressure: 73 mmHg at 20°C
Solubility: Partially soluble in water (3% w/w at 25°C); fully miscible with alcohols, ethers, and hydrocarbons.
Chemical Properties:
Hydrolysis Stability: Hydrolyzes slowly in acidic/alkaline conditions to acetic acid and ethanol.
Thermal Stability: Decomposes above 350°C, releasing CO₂ and hydrocarbons.
Flammability: Highly flammable (flash point: -4°C; autoignition temperature: 427°C).
2. Industrial Applications
Solvents:
Coatings & Inks: Primary solvent for nitrocellulose lacquers, acrylics, and flexographic inks.
Adhesives: Dissolves resins in rubber-based adhesives and nail polish.
Pharmaceuticals:
Extraction & Purification: Isolates antibiotics, vitamins, and natural products.
Food & Flavors:
Food Additive: Imparts fruity notes in confectionery and beverages (GRAS status: FDA 21 CFR 172.515).
Chemical Synthesis:
Intermediate: Produces acetoacetate esters, pharmaceuticals, and fragrances.
3. Safety and Toxicology
Acute Exposure:
Inhalation (≥400 ppm): Irritates respiratory tract; causes dizziness (TLV-TWA: 400 ppm).
Skin Contact: Mild irritation (rabbit skin LD₅₀: >5,000 mg/kg); negligible absorption.
Ingestion: Low toxicity (oral LD₅₀ rat: 5,600 mg/kg); gastrointestinal discomfort.
Chronic Effects:
Carcinogenicity: Not classified by IARC or NTP; no mutagenicity (Ames test negative).
Reproductive Toxicity: No teratogenicity observed in OECD 414 studies.
Protection Measures:
PPE: Nitrile gloves, vapor respirators, and explosion-proof ventilation.
Storage: Store in flame-resistant containers away from oxidizers and heat sources.
4. Environmental and Regulatory Compliance
Environmental Impact:
Biodegradability: Rapid (OECD 301F: >90% degradation in 28 days).
Aquatic Toxicity: LC₅₀ (fish, 96h): 100–200 mg/L; EC₅₀ (daphnia, 48h): 50–100 mg/L.
VOC Status: Classified as a volatile organic compound (VOC) in the EU and USA.
Regulatory Frameworks:
EU:
REACH: Registered (EC 205-500-4); CLP classified as Flam. Liq. 2 (H225).
USA:
EPA: Regulated under TSCA; listed as a VOC under Clean Air Act.
FDA: Approved as a food additive (21 CFR 172.515).
China:
GB 2760-2014: Permitted as a food flavoring agent.
Waste Management:
Incinerate in approved facilities with VOC abatement; landfill disposal prohibited.
5. Case Studies and Application Insights
Case 1: Low-VOC Automotive Coatings (BASF, 2023):
Challenge: Reduce VOC emissions in automotive spray paints.
Solution: Replaced 30% of toluene with ethyl acetate.
Result: Achieved 25% lower VOC emissions (ASTM D6886) and maintained drying time (ASTM D5895).
Case 2: Sustainable Food Packaging (Nestlé, 2022):
Process: Used ethyl acetate to extract natural flavors for biodegradable packaging coatings.
Impact: Reduced synthetic solvent use by 40% and met EU Ecolabel standards.
Comparative Analysis:
Ethyl Acetate vs. Acetone:
Pros: Lower toxicity (higher LD₅₀); pleasant odor; GRAS status for food use.
Cons: Higher flammability (flash point -4°C vs. -20°C).
Ethyl Acetate vs. Methyl Ethyl Ketone (MEK):
Pros: Better biodegradability; lower neurotoxicity risk.
Cons: MEK offers faster evaporation for industrial coatings.
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula CH3COOH (also written as CH3CO2H, C2H4O2, or HC2H3O2). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. It has been used, as a component of vinegar, throughout history from at least the third century BC.
Acetic acid is the second simplest carboxylic acid (after formic acid). It is an important chemical reagent and industrial chemical across various fields, used primarily in the production of cellulose acetate for photographic film, polyvinyl acetate for wood glue, and synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is controlled by the food additive code E260 as an acidity regulator and as a condiment. In biochemistry, the acetyl group, derived from acetic acid, is fundamental to all forms of life. When bound to coenzyme A, it is central to the metabolism of carbohydrates and fats.
The global demand for acetic acid is about 6.5 million metric tonnes per year (t/a), manufactured from methanol. Its production and subsequent industrial use poses health hazards to workers, including incidental skin damage and chronic respiratory injuries from inhalation.