1. Chemical Structure and Properties

Molecular Formula: C₁₄H₂₆O₄

Structural Formula: CH₂CH₂COO(CH₂)₃CH₃ — A diester compound formed by the reaction of adipic acid with butanol.

Physical Properties:
     Appearance: Clear, colorless to pale yellow oily liquid with a faint ester-like odor.
     Boiling Point: 305°C; Density: 0.96 g/cm³; Vapor Pressure: 0.001 mmHg at 25°C.
     Solubility: Insoluble in water; miscible with most organic solvents (ethanol, acetone, ether).

Chemical Properties:
     Stability: Hydrolyzes slowly under strong acidic/alkaline conditions; stable under normal storage.
     Flammability: Combustible liquid (flash point: 148°C).
     Viscosity: ~10 mPa·s at 20°C.

2. Industrial Applications

Plasticizers:
     Primary Use: Secondary plasticizer for PVC, improving flexibility and cold resistance in cables, flooring, and films.
     Synergy: Often blended with primary phthalate-free plasticizers (e.g., DINCH) to enhance performance.

Cosmetics:
     Emollient: Used in lotions, creams, and hair conditioners for its non-greasy texture.

Lubricants:
     Synthetic Base Oil: Reduces friction in industrial machinery and food-grade applications.

Coatings:
     Solvent: Carrier for resins in automotive and wood coatings.

3. Safety and Toxicology

Health Hazards:
     Acute Exposure:
     Oral LD₅₀ (Rat): >5,000 mg/kg (practically non-toxic).
     Skin Irritation: Mild irritation (rabbit skin LD₅₀: >2,000 mg/kg).
     Eye Exposure: Transient discomfort (OECD 405 compliant).

Chronic Effects:
     No evidence of carcinogenicity (IARC: Not listed); low reproductive toxicity (OECD 421/422).

Handling Precautions:
     PPE: Nitrile gloves and safety goggles for bulk handling.
     Storage: Inert containers away from strong acids/bases.

4. Environmental and Regulatory Compliance

Environmental Impact:
     Aquatic Toxicity: LC₅₀ (fish, 96h): >100 mg/L; EC₅₀ (daphnia): >50 mg/L.
     Biodegradability: Readily biodegradable (OECD 301F: >70% in 28 days).
     Persistence: Low bioaccumulation potential (log Kow: 4.5).

Regulatory Frameworks:
     EU: REACH-registered; exempt from SVHC listing.
     USA: FDA 21 CFR 175.300 compliant for indirect food contact; EPA TSCA-listed.
     China: GB 9685-2016 approved for food packaging materials.

Transport:
     UN Number: Non-hazardous; general chemical transport.

5. Case Studies and Application Insights

Case 1: Eco-Friendly PVC Flooring:
     Application: Replaced 30% of DINCH with dibutyl adipate in PVC flooring to meet EU REACH low-VOC standards.
     Result: 15% improvement in low-temperature flexibility (-20°C).

Case 2: Food-Grade Lubricant Formulation:
     Process: Blended with polyalkylene glycol (PAG) for NSF H1-certified lubricants in bottling plants.
     Performance: Reduced wear by 40% vs. mineral oil-based lubricants.

Comparative Analysis:
     Dibutyl Adipate vs. Dioctyl Adipate (DOA):
     Pros: Lower viscosity, better compatibility with polar polymers.
     Cons: Higher volatility limits use in high-temperature applications.