Propylene carbonate, Propylenecarbonate, 108-32-7 

Propylene Carbonate, Propylenecarbonate, 108-32-7

• Chemical Name: Propylene Carbonate

• CAS Number: 108-32-7

• Molecular Formula: C4H6O3

• Molar Mass: 102.09 g/mol

• Structure: Cyclic carbonate (five-membered ring)

• Synonyms: 1,2-Propanediol carbonate, 4-Methyl-1,3-dioxol-2-one, 1-Methylethylene carbonate

Physical and Chemical Properties

• Density: 1.204 g/mL at 25 °C

• Melting Point: -49 to -55 °C

• Boiling Point: 238–240 °C

• Flash Point: 128 °C

• Refractive Index: 1.421

• Vapor Pressure: 0.13 mmHg at 20 °C

• Water Solubility: 240 g/L at 20 °C

• Appearance: Colorless, odorless, flammable liquid

• pKa: 3.92 at 20 °C

• pH: 6.0–7.5 (200 g/L aqueous solution)

• Miscibility: Soluble in water, benzene, chloroform, ethyl acetate, carbon tetrachloride

Production Methods

1. Phosgene Method:

   • Reaction of propylene glycol with phosgene → hydroxyisopropyl chloroformate

   • Neutralization with sodium hydroxide → propylene carbonate

   • Purification by vacuum distillation

   • Drawback: High toxicity risk due to phosgene

2. Transesterification Method:

   • Reaction of propylene glycol with dialkyl carbonates

3. Chloropropanol Method:

   • Conversion of chloropropanol derivatives

4. Propylene Oxide + CO₂ Method (Green Synthesis):

   • Reaction at 150–160 °C and 5 MPa

   • Fractionation under reduced pressure

   • Advantage: Utilizes CO₂ as raw material, contributing to greenhouse gas reduction

   • Catalysts: Potassium carbonate, tin-organic compounds, heterogeneous catalysts

Industrial Applications

• Solvent: For synthetic fibers, polymers, dyes, pigments

• Plasticizer: In polymer processing

• Extractant: For olefins and aromatic hydrocarbons

• Energy Storage: Electrolyte in lithium-ion batteries, stabilizes graphite anodes

• Chemical Industry: Raw material for dimethyl carbonate synthesis

• Gas Purification: Removal of CO₂ and H₂S from natural gas and petroleum cracking gas

• Adhesives: Substitute for phenolic resin in wood adhesives

• Analytical Chemistry: Stationary phase in gas chromatography, mineral beneficiation

• Coatings and Inks: Used in UV-curable formulations

Toxicity and Safety

• Hazard Classification: Xi – Irritant

• Risk Code: R36 – Irritating to eyes

• Oral LD50 (rat): 34,900 mg/kg

• Oral LD50 (mouse): 20,700 mg/kg

• Dermal LD50 (rabbit): > 20,000 mg/kg

• Irritation Data:

  • Skin (rabbit, 500 mg): Moderate irritation

  • Eye (rabbit, 60 mg): Moderate irritation

• Fire Hazard: Flammable under open flame, high temperature, or oxidizing conditions

• Fire Extinguishing Agent: Alcohol foam recommended

• Storage: Sealed containers, below 30 °C, well-ventilated, away from fire and oxidants

Environmental and Strategic Importance

• Green Chemistry: CO₂ fixation into chemicals via synthesis route contributes to sustainability.

• Energy Sector: Critical role in lithium-ion battery electrolytes and high-energy capacitors.

• Versatility: Functions as both solvent and raw material, making it valuable across multiple industries.