C2H5I

C2H5I, known as ethyl iodide, is an organoiodine compound and one of the simple alkyl iodides. Its formula is C2H5I and its molecular weight is about 156 g/mol. It is a colorless, volatile liquid with a boiling point near 72 °C and limited miscibility with water; it is more soluble in organic solvents. In water, it slowly undergoes hydrolysis to ethanol and hydroiodic acid: C2H5I + H2O → C2H5OH + HI.

Preparation and handling methods reflect its reactivity. Ethyl iodide is typically prepared from ethanol using hydroiodic acid or via red phosphorus and iodine, among other routes. Due to its high reactivity, it readily undergoes nucleophilic substitution (SN2) with a wide range of nucleophiles. As such, it is used as a versatile ethylating reagent in organic synthesis, enabling the introduction of an ethyl group into amines, thiols, alcohols, and other nucleophiles, as well as for converting alcohols into alkyl iodides.

Safety and hazards are significant considerations. Ethyl iodide is corrosive and a strong lachrymator; exposure through inhalation or skin contact can be harmful. It reacts with water and air; it should be handled in a well-ventilated fume hood, with appropriate protective equipment, and stored in a tightly closed container away from moisture and heat sources.

See also: alkyl halides, organoiodine reagents, SN2 reactions.