In organic chemistry, an ethyl group (abbr. Et) is an alkyl

substituent A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as ''side ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

, derived from ethane (). ''Ethyl'' is used in the International Union of Pure and Applied Chemistry's nomenclature of organic chemistry for a saturated two-carbon

moiety Moiety may refer to: Chemistry * Moiety (chemistry), a part or functional group of a molecule ** Moiety conservation, conservation of a subgroup in a chemical species Anthropology * Moiety (kinship), either of two groups into which a society is ...

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 Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

to yield ethylbenzene, a precursor to styrene, which is a precursor to

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...

. Approximately 24.7 million tons of ethylbenzene were produced in 1999. :: EtC6H5route

Many ethyl-containing compounds are generated by

electrophilic In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carri ...

ethylation, i.e. treatment of

nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

s with sources of Et⁺. Triethyloxonium tetrafluoroborate t₃OF₄ is such a reagent. For good nucleophiles, less electrophilic reagents are employed, such as ethyl

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...

Stereochemistry

In unsymmetrical ethylated compounds, the methylene protons in the ethyl substituent are

diastereotopic In stereochemistry, topicity is the stereochemical relationship between substituents and the structure to which they are attached. Depending on the relationship, such groups can be ''heterotopic'', ''homotopic'', ''enantiotopic'', or ''diastereotopi ...

. 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 In philosophy, hyle (; from grc, ὕλη) refers to matter or stuff. It can also be the material cause underlying a change in Aristotelian philosophy. The Greeks originally had no word for matter in general, as opposed to raw material suitable ...

", referring to "stuff". The name "ethyl" was coined in 1835 by the Swedish chemist

Jöns Jacob Berzelius Baron Jöns Jacob Berzelius (; by himself and his contemporaries named only Jacob Berzelius, 20 August 1779 – 7 August 1848) was a Swedish chemist. Berzelius is considered, along with Robert Boyle, John Dalton, and Antoine Lavoisier, to be on ...

.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'' nnual report on progress in physics and chemistry(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 neC₄H₁₀, ''ethyl'', the newer neC₂H₆, ''methyl'', … ote: At that time, chemists used the wrong atomic masses (e.g., 6 for carbon instead of 12); hence the coefficients shown here must be divided by two. In his translation into German of Berzelius' report, the German chemist

Friedrich Wöhler Friedrich Wöhler () FRS(For) HonFRSE (31 July 180023 September 1882) was a German chemist known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the firs ...

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.

References

{{Functional group Alkyl groups

Ethylation

Stereochemistry

Etymology

See also

References