Chloroethane
Chloroethane, chemically designated as CH₃CH₂Cl and commonly referred to as ethyl chloride, is a halogenated aliphatic hydrocarbon that appears as a colorless, flammable gas or volatile liquid with a mildly sweet odor under standard conditions.[1] It possesses a boiling point of 12.3 °C and a melting point of −139 °C, rendering it gaseous at room temperature but easily liquefied for handling.[2] Produced industrially via the chlorination of ethane or the reaction of ethanol with hydrochloric acid, chloroethane serves primarily as a chemical intermediate in the synthesis of compounds such as tetraethyllead (formerly used as an antiknock additive in gasoline), ethyl cellulose, and certain pharmaceuticals and dyes.[3] It also finds application as a solvent, refrigerant, and, historically, as a general anesthetic following its introduction in surgical practice in 1847, though contemporary medical use is largely confined to topical anesthesia for minor skin procedures due to its rapid evaporation and local freezing effect.[4] Chloroethane exhibits significant hazards, including high flammability—forming explosive mixtures with air—and acute toxicity upon inhalation, which can induce central nervous system depression, intoxication-like symptoms, tremors, unconsciousness, or even death in high concentrations, alongside potential cardiac sensitization and organ damage with repeated exposure.[5][6][7] Its environmental persistence and contribution to atmospheric chlorine loading have prompted regulatory scrutiny in certain applications, though it lacks the ozone-depleting potency of chlorofluorocarbons.[8]Chemical Properties
Molecular Structure and Formula
Chloroethane has the molecular formula C₂H₅Cl, corresponding to a molecular weight of 64.514 g/mol.[9] [1] The compound's IUPAC name is chloroethane, reflecting its systematic nomenclature as a substituted ethane.[9] [1] The structural formula is CH₃CH₂Cl, depicting an ethyl group (C₂H₅) bonded to a chlorine atom via a single covalent bond on the primary carbon.[1] [10] This configuration classifies chloroethane as a primary alkyl halide, with the chlorine substituting one terminal hydrogen in ethane (C₂H₆).[1] The molecule's InChI representation is InChI=1S/C2H5Cl/c1-2-3/h2H2,1H3, and its SMILES notation is CCCl, standardizing its depiction in chemical databases.[9] [1] Both carbon atoms in chloroethane exhibit sp³ hybridization, leading to tetrahedral geometry with approximate bond angles of 109.5° around each carbon center.[1] The carbon-chlorine bond is polar covalent, with the electronegative chlorine drawing electron density from the less electronegative carbon, contributing to the molecule's overall dipole moment.[1] Chloroethane lacks chiral centers and stereoisomers due to its symmetric substitution on an achiral carbon framework.[1]Physical Characteristics
Chloroethane exists as a colorless gas under standard temperature and pressure conditions, exhibiting a pungent, ether-like odor detectable at low concentrations. When cooled below its boiling point or subjected to pressure, it forms a colorless, mobile liquid that is highly volatile.[10][11][12] Its melting point is -138.7 °C, and the boiling point is 12.3 °C at 760 mmHg, rendering it gaseous at ambient temperatures above this threshold.[10][7] The liquid density is 0.918 g/cm³ relative to water at approximately 12 °C, while vapor density is 2.22 relative to air, causing vapors to sink and accumulate in low-lying areas.[13][11] Chloroethane demonstrates limited solubility in water, at 0.574 g/100 mL at 20 °C, but is miscible with many organic solvents such as ethanol and diethyl ether.[13][11] Vapor pressure is notably high, reaching 1000 mmHg at 20 °C, contributing to its rapid evaporation and flammability, with a flash point of -50 °C.[14][15]| Property | Value | Conditions |
|---|---|---|
| Molecular weight | 64.51 g/mol | - |
| Appearance | Colorless gas/liquid | RTP / pressurized |
| Odor threshold | Pungent, ether-like | Detectable low ppm |