How Dioctyl Adipate (DOA) Is Made – BASTONE Plasticizer Manufacturer in China

Dioctyl Adipate (Plasticizer DOA) is a highly efficient, low-temperature-resistant plasticizer widely used in flexible PVC, cables, synthetic leather, and film applications.

1. Introduction

The chemical synthesis of DOA is an esterification reaction between adipic acid and 2-ethylhexanol (isooctyl alcohol). The reaction is equilibrium-controlled and requires the removal of water to drive completion.

Raw Materials: High-purity adipic acid and 2-ethylhexanol (octanol)

Molar Ratio: Adipic acid : Octanol = 1 : 2.3–2.5

Catalyst: for example, Composite system of tetrabutyl titanate and p-toluenesulfonic acid (PTSA)

Catalyst Ratio: 3 : 1 (mass ratio)

Catalyst Dosage: 0.8%–1.2% of total reactant mas

2. Produciton process

2.1 Step 1 Esterification Process (Two-Stage Reaction)

Stage 1 – Low-Temperature Dehydration

• Temperature: 120–130 °C
• Time: ~1.5 hours
• Purpose: Remove ~85% of reaction-generated water to drive the reaction forward

Stage 2 – High-Temperature Esterification

• Temperature: 160–170 °C
• Time: Maintain for ~3 hours
• Procedure: Continuously remove water through the separator
• Reaction Endpoint: When acid value < 2 mg KOH/g, esterification is considered complete

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2.2. Post-Treatment and Purification

The crude ester undergoes three purification steps to ensure clarity and high purity:

1. Alkali Washing:
   Wash twice with 5% sodium carbonate solution to neutralize residual acidic catalysts.
2. Water Washing:
   Rinse with deionized water until neutral pH to remove salts.
3. Vacuum Distillation:
   Conducted under 0.095 MPa vacuum, collecting fractions at 240–250 °C to obtain high-purity DOA.

BASTONE continues to deliver world-class plasticizers like DOP, DOTP, DINP, DOA, and DPHP that enhance PVC flexibility, stability, and performance.
To learn more about our plasticizer solutions, visit: https://bastone-plastics.com/product-category/plasticizer/