Dibutyl adipate (DBA) is a low-molecular-weight adipate ester used as a plasticizer for PVC and other polymers. It’s the chemical result of combining adipic acid with butanol, creating a clear, oily liquid that lowers a polymer’s glass-transition temperature and keeps it flexible at low temperatures.
Its molecular formula is C₁₄H₂₆O₄, and it appears as a colorless liquid with a mild, ester-like smell that’s barely noticeable in finished compounds. For flexible PVC that needs cold-flex performance, higher-molecular-weight adipates such as DOA (dioctyl adipate) are the mainstream choice, with DBA serving faster-fusing, lower-viscosity roles.
Chemical Identity and Structure of Dibutyl Adipate
| Property | Value |
|---|---|
| Chemical Name | Dibutyl adipate (di-n-butyl ester of adipic acid) |
| CAS Number | 105-99-7 |
| Molecular Formula | C₁₄H₂₆O₄ |
| Molecular Weight | 258.36 g/mol |
| Physical State | Clear, colorless oily liquid |
| Odor | Mild ester-like smell |
| Melting Point | -10°C |
| Boiling Point | 300-305°C at 760 mmHg |
| Density | 0.96 g/mL at 25°C |
| Water Solubility | 4-6 mg/L at 25°C (practically insoluble) |
| Vapor Pressure | 0.001-0.002 mmHg at 25°C (very low volatility) |
| Partition Coefficient (log Kow) | 4.3-4.4 |
| Other Names | Hexanedioic acid dibutyl ester, Adipic acid dibutyl ester, Cetiol B, Adimoll DB |
Common Applications of Dibutyl Adipate
- Plasticizer in PVC and other polymers: Makes PVC flexible by lowering its glass-transition temperature. It’s especially useful in films, coatings, and adhesives where fast fusion and low-temperature flexibility matter.
- Food-contact films: FDA-approved for use in materials that contact food, including packaging films and adhesives where it helps maintain flexibility.
- Printing ink plasticizer: Serves as a plasticizing solvent that improves ink flow and adhesion properties.
- Floor polish component: Makes up about 10% of certain floor waxes and polishes, creating a smooth protective film that adds gloss without quick evaporation.
Is Dibutyl Adipate Toxic
Dibutyl adipate has low acute toxicity and is generally safe for humans at normal exposure levels. The oral LD50 in rats is 12-13 g/kg body weight, which means you’d need to consume massive amounts to experience harmful effects.
The compound can cause mild skin irritation when applied undiluted, producing slight redness and swelling that goes away quickly. However, it’s not a skin sensitizer and doesn’t cause allergic reactions in most people.
Long-term studies show no significant organ damage or health problems at doses up to 1000 mg/kg per day. The substance isn’t carcinogenic, mutagenic, or genotoxic according to multiple safety assessments by regulatory agencies.
FAQs
How does dibutyl adipate differ from phthalates?
Dibutyl adipate is an adipate ester that’s readily biodegradable and has lower toxicity than many phthalate plasticizers, making it a safer alternative for cosmetics and consumer products.
What happens if dibutyl adipate gets in water?
It biodegrades quickly in water, with 86-95% breaking down within 28 days, though it can harm aquatic life at concentrations above 3 mg/L.
Is dibutyl adipate natural or synthetic?
It’s a synthetic compound made by combining adipic acid with butanol through an esterification process.
How does DBA compare to DOA and DINA for flexible PVC?
DBA is a lower-molecular-weight adipate, so it fuses faster and has lower viscosity but migrates more readily than DOA or DINA. For durable cold-flex PVC (wire, film, tubing), higher-MW adipates like DOA are usually specified; DBA suits fast-processing or low-viscosity roles.