By Lan Luo | Updated Aug 30, 2022
Anhydrous diethyl ether (C4H10O) is a distilled, water‑free form of diethyl ether, a simple ether with the general structure R-O-R’. It is widely used as a laboratory solvent due to its low boiling point and high polarity for many organic reactions.
Diethyl ether is a colorless liquid with a characteristic sweet, hot odor. Its boiling point is 34.6 °C and its melting point is –116.3 °C. The molecule, CH3‑CH2‑O‑CH2‑CH3, is highly flammable and volatile. While ethers are chemically stable, diethyl ether can form peroxides when exposed to air and light, and it is a moderate Lewis and Brønsted base—making it an essential solvent for Grignard reagents.
Industrial production typically employs acid‑catalyzed dehydration of ethanol at 130–140 °C, yielding ether and water. The reaction is catalyzed by sulfuric acid:
2 CH3CH2OH → CH3CH2OCH2CH3 + H2O
At temperatures above 150 °C, ethanol can dehydrate to ethylene, so the ether route is preferred for large‑scale synthesis. For laboratory use, the crude ether is dried over sodium or with molecular sieves (4 Å pore size) before distillation to obtain anhydrous product.
Historically, diethyl ether served as a surgical anesthetic, providing a larger safety margin than chloroform. Modern medicine has largely replaced it with safer agents. Today, it remains a staple solvent for organic synthesis, liquid‑liquid extraction, and the production of cellulose‑based plastics. Its low flash point also makes it useful as a starting fluid in cold‑climate engines.
Inhalation can cause nausea, vomiting, and loss of consciousness; direct contact may irritate or burn skin and eyes. Diethyl ether is extremely flammable and can ignite with flame, heat, or static discharge. Exposure to air and light promotes explosive peroxide formation—particularly problematic when the solvent is evaporated to dryness. Commercial ether is often stabilized with butylated hydroxytoluene (BHT) to suppress peroxide generation, and peroxide test strips are recommended for routine checks.
