By Michael Judge
Updated August 30, 2022
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In many laboratories, the names petroleum ether and diethyl ether can lead to confusion. Though both are solvents, they are chemically distinct, have different physical properties, and are not interchangeable. Understanding their differences is essential for safe handling and proper application.
Diethyl ether (C₂H₅OCH₂CH₃) is a single, well‑defined organic compound. Its structure contains an oxygen atom bonded to two carbon chains, fitting the classic ether definition.
Petroleum ether is not an ether at all. It is a commercial blend of alkanes, primarily pentane (C₅H₁₂) and hexane (C₆H₁₄), produced by fractional distillation of petroleum. The exact composition varies by supplier.
Diethyl ether is a clear, colorless liquid that freezes at –116 °C and boils at 35 °C. Its vapors are sweet‑smelling, heavier than air, and highly flammable even at sub‑zero temperatures.
Petroleum ether is also colorless but has a boiling point of about 38 °C and a gasoline‑like odor. Its vapors can ignite at temperatures as low as –18 °C, posing a fire risk in poorly ventilated areas.
Both solvents are irritants. Inhalation of high concentrations can cause eye, skin, and respiratory irritation, loss of consciousness, and even coma. Chronic exposure to diethyl ether may lead to liver damage. Petroleum ether ingestion or inhalation can also induce coma and has been classified as an animal carcinogen.
NIOSH sets an immediately dangerous to life or health (IDLH) limit of 1,900 ppm for diethyl ether. For petroleum ether, the acceptable airborne concentration is about 350 ppm over an 8‑hour workday. Animal studies have shown fatality thresholds of 3,400 ppm (4 h) for petroleum ether in rats and 31,000 ppm (30 min) for diethyl ether in mice.
Always use appropriate personal protective equipment and adequate ventilation when handling either solvent. When in doubt, consult the Material Safety Data Sheet (MSDS) for the specific product you are using.
