Diethyl phthalate
[CAS# 84-66-2]

Identification

• Classification: Flavors and spices >> Synthetic spice >> Carboxylic acid and ester perfume >> Aromatic carboxylic acid ester
• Name: Diethyl phthalate
• Synonyms: 1,2-Benzenedicarboxylic acid diethyl ester
• Molecular Formula: C₁₂H₁₄O₄
• Molecular Weight: 222.24
• CAS Registry Number: 84-66-2
• EC Number: 201-550-6
• SMILES: CCOC(=O)C1=CC=CC=C1C(=O)OCC

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*, 1.12 g/mL (Expl.)
• Melting point: -3 °C (Expl.)
• Boiling point: 294.0 °C 760 mmHg (Calc.)^*, 298 - 299 °C (Expl.)
• Flash point: 160.0 °C (Calc.)^*, 156 °C (Expl.)
• Solubility: 0.1 g/100g (Expl.)
• Index of refraction: 1.508 (Calc.)^*, 1.502 (Expl.)

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

Safety Data

• Hazard Symbols: GHS08 Warning
• Risk Statements: H361
• Safety Statements: P281-P201-P202-P308+P313-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	3	H331
Reproductive toxicity	Repr.	2	H361
Acute toxicity	Acute Tox.	4	H332
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	1	H332
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute toxicity	Acute Tox.	1	H312
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	1	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412

Discovery and Applications

Diethyl phthalate is a colorless, oily liquid belonging to the class of chemical compounds known as phthalate esters. It is produced by the esterification of phthalic anhydride with ethanol. This compound is one of the simpler phthalate esters and has been widely studied and utilized due to its favorable properties such as low volatility, good plasticizing effect, and relatively low toxicity compared to other phthalates.

The discovery and use of diethyl phthalate date back to the early 20th century, coinciding with the development of phthalate esters as plasticizers. Plasticizers are substances added to polymers to increase flexibility, softness, and workability. Diethyl phthalate was initially employed as a plasticizer for cellulose acetate, cellulose nitrate, and other polymers, improving their mechanical properties and processing behavior.

Apart from its role as a plasticizer, diethyl phthalate has found extensive applications in various industries. It is used as a solvent and fixative in the formulation of perfumes and cosmetics, where it helps to stabilize fragrances and prolong their evaporation time. This property made it popular in personal care products such as deodorants, hairsprays, and aftershaves.

In addition to cosmetics, diethyl phthalate serves as a carrier solvent for insecticides, fungicides, and other agricultural chemicals. Its ability to dissolve a wide range of active ingredients while being relatively non-volatile enhances the stability and application efficiency of these products.

Diethyl phthalate has also been used as a plasticizer in the production of lacquers, inks, adhesives, and coatings. Its compatibility with different resin systems and its resistance to migration contribute to improved durability and flexibility of coated materials.

The chemical properties of diethyl phthalate, including its solubility in organic solvents and limited water solubility, influence its behavior in applications and environmental fate. It is biodegradable under aerobic conditions, and its toxicity profile has been extensively evaluated. Although considered less hazardous than some other phthalates, regulatory scrutiny regarding its use has increased due to concerns over endocrine disruption associated with phthalate esters in general.

Manufacturing of diethyl phthalate involves the catalytic esterification of phthalic anhydride with ethanol, typically using acid catalysts under controlled conditions to optimize yield and purity. The product is then purified to remove unreacted materials and by-products.

In summary, diethyl phthalate is a widely used phthalate ester produced by esterification of phthalic anhydride and ethanol. Its primary applications include functioning as a plasticizer in polymers, solvent and fixative in cosmetics and perfumes, and carrier solvent in agricultural formulations. Its chemical stability, plasticizing effect, and solvent properties have established it as an important industrial chemical, although its use is subject to ongoing evaluation concerning safety and environmental impact.

References

2005. Evidence of Interaction between Polychlorinated Biphenyls and Phthalates in Relation to Human Sperm Motility. Environmental Health Perspectives, 113(4).
DOI: 10.1289/ehp.7305

2021. Effects of bisphenol A or diethyl phthalate on cartilage development and the swimming behavior of zebrafish (Danio rerio) through maternal exposure. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 247.
DOI: 10.1016/j.cbpc.2021.109057

2024. Distribution of Phthalic Acid Esters (PAEs) in Personal Care Products and Untreated Municipal Wastewater Samples: Implications for Source Apportionment and Ecological Risk Assessment. Water, Air, & Soil Pollution, 235(12).
DOI: 10.1007/s11270-024-07679-0