In organic chemistry, an ethyl group (abbreviated as ET, Et or et)
Ethyl is used in the International Union of Pure and Applied Chemistry's nomenclature of organic chemistry for a saturated two-carbon moiety in a molecule, while the prefix " eth-" is used to indicate the presence of two carbon atoms in the molecule.
Ethylation
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 with
ethylene to yield
ethylbenzene, a precursor to
styrene, which is a precursor to
polystyrene. Approximately 24.7 million tons of ethylbenzene were produced in 1999.
- :
Many ethyl-containing compounds are generated by electrophilic ethylation, i.e. treatment of with sources of Et+. Triethyloxonium tetrafluoroborate Et3OBF4 is such a reagent. For good nucleophiles, less electrophilic reagents are employed, such as ethyl .
Stereochemistry
In unsymmetrical ethylated compounds, the methylene protons in the ethyl substituent are
diastereotopic. Chiral reagents are known to stereoselectively modify such substituents.
Etymology
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.
[In 1834, the German chemist Justus Liebig had argued that the group C2H5 constituted a "radical" (a cluster of atoms that did not undergo changes during chemical reactions). (See: Justus Liebig (1834) "Ueber die Constitution des Aethers und seiner Verbindungen" (On the composition of ethers and their compounds), Annalen der Pharmacie, 9 : 1–39.) In reporting on Liebig's findings (and related work by others), Berzelius coined the names "methyl" and "ethyl" for the "radicals" CH3 and C2H5, respectively. From Jacob Berzelius, Årsberättelsen om framsteg i fysik och kemi Annual (Stockholm, Sweden: P.A. Norstedt & Söner, 1835), p. 376: "Man får då ge namn åt etherradikalerna; man kan kalla den äldre C4H10, ethyl , den nyare C2H6, methyl , … " (One may then give names to ether radicals; one can call the older one C4H10, ethyl, the newer one C2H6, methyl, … Note:) In his translation into German of Berzelius' report, the German chemist Friedrich Wöhler transliterated "ethyl" as "Aethyl". (See: Jöns Jacob Berzelius with Friedrich Wöhler, trans., Jahresbericht über die Fortschritte der physischen Wissenschaften (Annual report on the progress of the physical sciences), 15 : 381.)]
See also
