Dioctyl phthalate
[CAS# 117-81-7]

Identification

• Classification: Chemical reagent >> Organic reagent >> Ester >> Other ester compounds
• Name: Dioctyl phthalate
• Synonyms: Bis(2-ethylhexyl) phthalate; Di-2-ethylhexyl phthalate; DOP
• Molecular Formula: C₂₄H₃₈O₄
• Molecular Weight: 390.56
• CAS Registry Number: 117-81-7
• EC Number: 204-211-0
• SMILES: CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 0.985 g/mL (Expl.)
• Melting point: -50 °C (Expl.)
• Boiling point: 384.9±10.0 °C 760 mmHg (Calc.)^*, 386 °C (Expl.)
• Flash point: 207.2 °C (Calc.)^*, 215 - 216.1 °C (Expl.)
• Solubility: water: negligible (3.0E-5 g/100g) (Expl.)
• Index of refraction: 1.489 (Calc.)^*, 1.486 (Expl.)

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

Safety Data

• Hazard Symbols: GHS08 Danger
• Risk Statements: H360FD:
• Safety Statements: P203-P280-P318-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Reproductive toxicity	Repr.	1B	H360
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	1B	H360FD
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Eye irritation	Eye Irrit.	2	H319
Reproductive toxicity	Repr.	1A	H360
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Reproductive toxicity	Repr.	1B	H360FD

Discovery and Applications

Dioctyl phthalate is a persistent plasticizer historically used to impart flexibility and durability to polyvinyl chloride (PVC) and other polymers Its chemical name is bis(2-ethylhexyl) phthalate and its molecular formula is C₂₄H₃₈O₄ comprising a phthalic acid core esterified with two branched 2-ethylhexanol groups This structure confers hydrophobicity low volatility and excellent compatibility with polymer matrices

Industrial production of dioctyl phthalate began in the 1930s following commercialization of PVC It is synthesized via acid-catalyzed esterification of phthalic anhydride with 2-ethylhexanol using catalysts such as sulfuric or p-toluenesulfonic acid with water removal to drive the reaction forward and purification to remove excess reagents The scalable process supported its widespread adoption in manufacturing

Dioctyl phthalate became prevalent in flexible PVC products such as cable insulation flooring wall coverings roofing membranes medical tubing and inflatable goods It absorbs mechanical stress prevents brittleness and enhances cold-weather performance Its favorable plasticizing efficiency and low cost contributed to its dominance until health and environmental concerns prompted regulatory review

Starting in the 1990s dioctyl phthalate was shown to leach from consumer products leading to human exposure through ingestion inhalation or dermal contact It is metabolized into mono(2-ethylhexyl) phthalate (MEHP) which exhibits endocrine-disrupting and reproductive toxicity in animal studies Consequently authorities such as the European Chemicals Agency and U S Consumer Product Safety Commission have restricted or banned its use in toys childcare articles and medical devices

Alternatives including diisononyl phthalate (DINP) di(2-ethylhexyl) terephthalate (DOTP) trimellitate and citrate esters have been developed However dioctyl phthalate remains used in certain industrial and specialty applications where alternatives fail to match performance or cost criteria

Recent research continues to explore dioctyl phthalate’s role and impact Molecular dynamics simulations investigate its plasticizing effects in PVC while greener synthesis and reactive extraction methods aim to boost production efficiency and reduce waste Review work surveys its prevalence in food-contact materials and regulations drive continued monitoring

In summary dioctyl phthalate is a chemically and industrially significant plasticizer with a well-documented history and synthesis whose extensive use has been curtailed by health and environmental concerns yet persists in specialized applications driven by its efficacy

References


Lei Q Yi X Yu W Cheng J Ou S Xue Q Jiang H (2025) Molecular dynamics simulation of plasticizing effect of mixed dioctyl phthalate and isosorbide diheptanoate on polyvinyl chloride material Polymers 17 1655 DOI: 10.3390/polym17121655


Qin H Zeng Q Cheng H Y Chen L F Qi Z W Wang R Z (2020) Reactive extraction strategy for synthesizing dioctyl phthalate intensified by bifunctional deep eutectic solvent Chem Eng Process 157 108060 DOI: 10.1016/j.cep.2020.108060


Tumu K Brown R J C von der Goltz L Tumu K et al (2023) Endocrine modulating chemicals in food packaging A review of phthalates and bisphenols Compr Rev Food Sci Food Saf 22 278–322 DOI: 10.1111/1541-4337.13113