Diethyl phthalate (DEP) is a versatile organic compound with its primary applications spanning the following areas:

I. Plasticizer (Core Application)

1. Cellulose Resin Plasticization: As the preferred plasticizer for nitrocellulose, cellulose acetate, and ethyl cellulose, it significantly enhances the elasticity, wear resistance, and low-temperature flexibility of plastic films, outperforming dimethyl phthalate (DMP);
2. Specialized Applications:
   • Non-toxic plasticizer for food packaging films (approved in multiple countries);
   • Plasticizing component in cosmetics (e.g., nail polish), improving film adhesion;
3. Compatibility with Other Resins: Compatible with resins such as polyvinyl acetate, polystyrene, and vinyl chloride-vinyl acetate copolymers, used in adhesives, coatings, and packaging materials.

II. Solvent and Chemical Intermediate

1. Organic Solvent: Dissolves cellulose, resins, and esters, used in formulations for paints, inks, and adhesives;
2. Gas Chromatography: Serves as a stationary phase (maximum operating temperature 95°C) for separating aromatic compounds, alcohols, ketones, and other oxygen-containing compounds;
3. Synthetic Intermediate:
   • Raw material for producing rodenticides (diphacinone, chlorophacinone);
   • Fixative in the fragrance industry, extending scent longevity.

III. Industrial Additives

1. Foaming Agent: Used in flotation processes for colored or rare metal ores, enhancing bubble stability;
2. Lubricant: Applied in mechanical lubrication or polymer processing;
3. Other Auxiliary Functions: Denaturant for alcohol, solvent for spray insecticides, and stabilizer for propellants.

IV. Emerging Biomedical Applications (Research Frontier)

1. Antibacterial Effect: Inhibits biofilm formation by blocking bacterial quorum-sensing signal proteins (LasR), potentially serving as a novel anti-infective agent;

?? Precautions

• Volatility Limitation: Its use as a plasticizer is limited due to high volatility;
• Safety: Low toxicity (oral LD?? in rabbits is 1000 mg/kg), but potential endocrine-disrupting properties warrant attention to compliance risks in contact products like cosmetics;
• Physical Properties: Density approximately 1.118–1.122 g/cm3 (20°C), boiling point 298°C, insoluble in water, soluble in ethanol and other organic solvents.