Ethyl group
In chemistry, an ethyl group is an alkyl substituent derived from ethane (C2H6). It has the formula –CH2CH3 and is very often abbreviated Et. Ethyl is used in the IUPAC nomenclature of organic chemistry for a saturated two-carbon moiety in a molecule, whilst the prefix "eth-" is used to indicate the presence of two carbon atoms in the molecule.
Ethylation is the formation of a compound by introduction of the ethyl group. The most widely practiced example of this reaction is the ethylation of benzene. The ethylating agent is ethylene.
Approximately 24.7 million tons were produced in 1999. Ethylbenzene is the precursor to styrene, the precursor to polystyrene.
Many ethyl-containing compounds are generated by electrophilic ethylation, i.e. treatment of nucleophiles with sources of Et+. Triethyloxonium tetrafluoroborate [Et3O]BF4 is such a reagent. For good nucleophiles, less electrophilic reagents are employed, such as ethyl halides.
In unsymmetrical ethylated compounds, the methylene protons in the ethyl substituent are diastereotopic. Chiral reagents are known to stereoselectively modify such substituents.
The name of the group is derived from the Aether, the first-born Greek elemental god of air (and at that time a general term for any highly volatile compound) and "hyle", referring to "stuff". The name "ethyl" was coined in 1835 by the Swedish chemist Jöns Jacob Berzelius.
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