Cyclobutane is a
cycloalkane and
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
with the formula (CH
2)
4. Cyclobutane is a colourless gas and commercially available as a
liquefied gas Liquefied gas (sometimes referred to as liquid gas) is a gas that has been turned into a liquid by cooling or compressing it. Examples of liquefied gases include liquid air, liquefied natural gas, and liquefied petroleum gas.
Liquid air
At the ...
. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commercial or biological significance, but more complex derivatives are important in biology and biotechnology.
Structure
The bond angles between
carbon atoms are significantly
strained and as such have lower
bond energies than related linear or unstrained hydrocarbons, e.g.
butane or
cyclohexane. As such, cyclobutane is unstable above about 500 °C.
The four carbon atoms in cyclobutane are not coplanar; instead the ring typically adopts a folded or "puckered"
conformation.
This implies that the C-C-C angle is less than 90°. One of the carbon atoms makes a 25° angle with the plane formed by the other three carbons. In this way some of the
eclipsing interactions are reduced. The conformation is also known as a "butterfly". Equivalent puckered conformations interconvert:
:
Cyclobutanes in biology and biotechnology
:
Despite inherent strain the cyclobutane motif is indeed found in nature. One unusual example is ''pentacycloanammoxic acid'', which is a
ladderane
In chemistry, a ladderane is an organic molecule containing two or more fused cyclobutane rings. The name arises from the resemblance of a series of fused cyclobutane rings to a ladder. Numerous synthetic approaches have been developed for the synt ...
composed of 5 fused cyclobutane units. The estimated strain in this compound is 3 times that of cyclobutane. The compound is found in bacteria performing the
anammox process where it forms part of a tight and very dense membrane believed to protect the organism from toxic
hydroxylamine
Hydroxylamine is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound.Greenwood and Earnshaw. ''Chemistry of the Elements.'' 2nd Edition. Reed Educational and Professional Publishing Ltd. pp. 431–43 ...
and
hydrazine involved in the production of nitrogen and water from
nitrite ions and
ammonia. Some related
fenestranes are also found in nature.
Cyclobutane photodimers (CPD) are formed by
photochemical reactions that result in the coupling of the C=C double bonds of
pyrimidines
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The other ...
.
Thymine dimers
Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA via photochemical reactions, commonly associated with direct DNA damage. Ultraviolet light (UV; particularly UVB) induces the formation of covalent linkages bet ...
(T-T dimers) formed in between two thymines are the most abundant of the CPDs. CPDs are readily repaired by
nucleotide excision repair enzymes. In most organisms they can also be repaired by photolyases, a light-dependent family of enzymes.
Xeroderma pigmentosum is a genetic disease where this damage can not be repaired, resulting in skin discolouration and tumours induced by exposure to
UV light.
:
Carboplatin is a popular
anticancer drug
Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...
that is derived from cyclobutane-1,1-dicarboxylic acid.
Preparation
Many methods exist for the preparation of cyclobutanes. Alkenes dimerize upon irradiation with UV-light. 1,4-Dihalobutanes convert to cyclobutanes upon dehalogenation with reducing metals.
Cyclobutane was first synthesized in 1907 by James Bruce and
Richard Willstätter
Richard Martin Willstätter FRS(For) HFRSE (, 13 August 1872 – 3 August 1942) was a German organic chemist whose study of the structure of plant pigments, chlorophyll included, won him the 1915 Nobel Prize for Chemistry. Willstätter invente ...
by hydrogenating cyclobutene in the presence of nickel.
See also
*
Butane
*
Octafluorocyclobutane
References
External links
* Datashee
Link
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Cycloalkanes
Cyclobutanes