monohaloethanes

Monohaloethanes are a class of organic compounds derived from ethane (C₂H₆) where one or more hydrogen atoms are replaced by a halogen atom—fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). They belong to the broader category of haloalkanes and are among the simplest halogenated hydrocarbons. The general formula for monohaloethanes is C₂H₅X, where X represents the halogen substituent.

The four monohaloethanes are chloroethane (ethyl chloride), bromoethane (ethyl bromide), iodoethane (ethyl iodide), and fluoroethane (ethyl fluoride). These compounds are colorless, volatile liquids with distinct odors, though some, like chloroethane, have a sweet, ether-like scent. They are highly flammable and exhibit varying degrees of reactivity due to the polar nature of the carbon-halogen bond, which influences their chemical behavior.

Monohaloethanes are primarily used as intermediates in organic synthesis. Chloroethane, for instance, serves as a precursor in the production of ethylenediamine and other chemicals. Bromoethane is often employed in the synthesis of pharmaceuticals and agrochemicals, while iodoethane is less common due to its higher cost and reactivity. Fluoroethane, though less common industrially, is studied for its potential as a refrigerant or propellant.

Environmentally, monohaloethanes are of concern due to their potential to contribute to ozone depletion and atmospheric pollution. Chloroethane, for example, can release chlorine radicals when photolyzed, which deplete stratospheric ozone. Their production and use are therefore subject to regulatory oversight under agreements like the Montreal Protocol.

Laboratory handling of monohaloethanes requires caution due to their toxicity and flammability. Prolonged exposure to vapors can irritate the respiratory system, and skin contact may cause dermatitis. Proper ventilation and protective equipment are essential when working with these compounds.