Chemical Properties and Structure
Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound with the chemical formula C₂H₆O₂. It consists of two hydroxyl (-OH) groups attached to adjacent carbon atoms in a two-carbon chain, forming a diol structure. This arrangement imparts high polarity and hydrogen bonding capability, resulting in elevated boiling and melting points compared to simpler alcohols. Ethylene glycol is a colorless, odorless, viscous liquid with a sweet taste, though it is highly toxic. It is miscible with water in all proportions and soluble in polar organic solvents like ethanol and acetone. Key physical properties include a melting point of -12.9 °C, a boiling point of 197.3 °C, and a density of 1.11 g/cm³ at 20 °C. Its hygroscopic nature makes it useful as a desiccant in industrial applications.
Production and Industrial Synthesis
The primary industrial method for producing ethylene glycol is the hydrolysis of ethylene oxide, a process that accounts for over 90% of global production. Ethylene oxide reacts with water under acidic or basic conditions, typically catalyzed by sulfuric acid or potassium hydroxide, to form ethylene glycol. This reaction is exothermic and occurs at moderate temperatures (50–100 °C) and pressures (1–5 bar). A smaller portion is synthesized via the traditional chlorohydrin process, which involves ethylene dichloride and calcium hydroxide, though this method has declined due to environmental and economic inefficiencies