Dioctyl sebacate
[CAS# 122-62-3]

Identification

• Classification: Catalysts and additives >> Plastic rubber additive
• Name: Dioctyl sebacate
• Synonyms: Bis(2-ethylhexyl)sebacate; Di(2-ethylhexyl)sebacate; DEHS
• Molecular Formula: C₂₆H₅₀O₄
• Molecular Weight: 426.68
• CAS Registry Number: 122-62-3
• EC Number: 204-558-8
• SMILES: CCCCCCCCOC(=O)CCCCCCCCC(=O)OCCCCCCCC

Properties

• Density: 0.9±0.1 g/cm³ Calc.^*, 0.914 g/mL (Expl.)
• Boiling point: 435.5 °C 760 mmHg (Calc.)^*, 503.1 °C (Expl.)
• Flash point: 189.7±18.2 °C (Calc.)^*
• Index of refraction: 1.454 (Calc.)^*, 1.45 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS09 Warning
• Risk Statements: H410
• Safety Statements: P273

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413

Discovery and Applications

Dioctyl sebacate, also known as di(2-ethylhexyl) sebacate or DOS, is a diester compound derived from sebacic acid and 2-ethylhexanol. It has been widely studied and utilized for its excellent plasticizing properties, thermal stability, and low volatility. The substance is a clear, oily liquid at room temperature, and it exhibits good compatibility with a wide range of polymers, especially polyvinyl chloride (PVC), which has made it a valuable plasticizer in industrial applications. Its molecular formula is C₂₆H₅₀O₄, and it has a relatively high molecular weight, which contributes to its performance in demanding environments.

The discovery and initial use of dioctyl sebacate can be traced to efforts in the mid-20th century to develop plasticizers with improved flexibility and resistance to cold temperatures. Unlike traditional phthalate plasticizers, which tend to become brittle under low-temperature conditions, dioctyl sebacate maintains flexibility and plasticity even at sub-zero temperatures. This unique property led to its adoption in military and aerospace-grade materials, where environmental extremes are common.

Dioctyl sebacate has been extensively applied as a plasticizer in the production of flexible PVC and other polymers. Its superior low-temperature characteristics have made it particularly useful in applications such as aircraft hydraulic fluid seals, automotive interiors, and flexible cables. In these environments, materials must retain their mechanical properties across wide temperature ranges. DOS has shown excellent performance in maintaining elasticity and preventing cracking under such conditions. Additionally, due to its high lubricity, it has also been incorporated into synthetic lubricants and hydraulic fluids, particularly for aviation applications. These formulations rely on the ester structure of dioctyl sebacate, which provides both lubricating properties and oxidative stability.

In the field of medical materials, dioctyl sebacate has been investigated for its potential use in medical-grade polymers, though concerns over the long-term migration and biocompatibility of plasticizers have limited its use in some applications. Nevertheless, its low toxicity profile compared to some other plasticizers has made it a candidate for controlled environments. It has also been used in the formulation of adhesives and sealants, especially those requiring flexibility and resistance to environmental degradation.

In analytical chemistry, dioctyl sebacate has been used as a matrix or internal standard in various chromatographic methods, particularly gas chromatography. Its chemical stability and non-polar nature make it suitable for use in the analysis of other esters or hydrophobic compounds. Furthermore, DOS has found niche roles in the field of nuclear technology, where it has been evaluated as a solvent or additive in extractant systems for metal ion separation due to its hydrophobic ester chains.

Due to increasing regulatory scrutiny over the use of certain plasticizers, dioctyl sebacate has also been considered a safer alternative in some jurisdictions. Its non-phthalate structure aligns with efforts to reduce dependence on phthalate-based additives, particularly in products intended for children or for food contact. Although it is not completely inert and can migrate under certain conditions, its relatively low environmental persistence and low bioaccumulation potential have contributed to its favorable environmental profile.

Despite its long history of use, research into dioctyl sebacate continues. New studies have explored its performance in biopolymer systems and its interactions with novel materials such as biodegradable plastics. These investigations aim to broaden its applicability while maintaining its well-documented performance advantages. As industries seek sustainable and high-performance materials, dioctyl sebacate remains a valuable component in the plasticizer and lubricant sectors, demonstrating how a well-characterized chemical can continue to play an essential role in evolving technological contexts.

References

2023. All-solid-state potentiometric salicylic acid sensor for in-situ measurement of plant. Analytical and Bioanalytical Chemistry, 415(7).
DOI: 10.1007/s00216-023-04616-8

2020. Ionic Liquids as Plasticizers for Optodes. Moscow University Chemistry Bulletin, 75(2).
DOI: 10.3103/s002713142002011x

2019. Replacement of Toxic Feedstocks in Chemical Synthesis. Green Chemistry and Chemical Engineering.
DOI: 10.1007/978-1-4939-9060-3_1002