Cyclooctyne is the
cycloalkyne
In organic chemistry, a cycloalkyne is the cyclic analog (chemistry), analog of an alkyne (). A cycloalkyne consists of a closed Ring (chemistry), ring of carbon atoms containing one or more triple bonds. Cycloalkynes have a general formula Becau ...
with a formula . Its molecule has a ring of 8
carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...
atoms, connected by seven
single bond
In chemistry, a single bond is a chemical bond between two atoms involving two valence electrons. That is, the atoms share one pair of electrons where the bond forms. Therefore, a single bond is a type of covalent bond. When shared, each of th ...
s and one
triple bond
A triple bond in chemistry is a chemical bond between two atoms involving six Electron pair bond, bonding electrons instead of the usual two in a covalent bond, covalent single bond. Triple bonds are stronger than the equivalent covalent bond, sin ...
.
Cyclooctyne is the smallest cycloalkyne that is stable enough to be isolated, although the chemical is still highly reactive. The alkyne region of the structure attempts to adopt a
linear molecular geometry
The linear molecular geometry describes the geometry around a central atom bonded to two other atoms (or ''ligands'') placed at a bond angle of 180°. Linear organic molecules, such as acetylene (), are often described by invoking sp orbital ...
, but the nature of the ring creates substantial
ring strain
In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles ar ...
. As a result, cyclooctyne and other compounds containing this ring structure readily react in ways that reduce the
ring strain
In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles ar ...
by converting the alkyne to a functional group that does not require linear geometry. An important application of this reactivity is in
click chemistry
Click chemistry is an approach to chemical synthesis that emphasizes efficiency, simplicity, selectivity, and modularity in chemical processes used to join molecular building blocks. It includes both the development and use of "click reactions", a ...
, where cyclooctynes undergo
cycloaddition
In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of th ...
reactions with
azide
In chemistry, azide (, ) is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant ...
s
or
nitrone
In organic chemistry, a nitrone is a functional group consisting of an Amine oxide, ''N''-oxide of an imine. The general structure is , where R3 is not a hydrogen. Their primary application is Chemical Intermediate, intermediates in chemical syn ...
s,
forming
triazole
A triazole is a heterocyclic compound featuring a five-membered ring of two carbon atoms and three nitrogen atoms with molecular formula C2H3N3. Triazoles exhibit substantial Isomer, isomerism, depending on the positioning of the nitrogen atoms w ...
s or
isoxazolines, respectively.
References
External links
*{{Commons category-inline
8
Eight-membered rings