Cyclobutanone is an

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

molecular formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

(CH₂)₃CO. It is a four-membered cyclic ketone (cycloalkanone). It is a colorless volatile liquid at room temperature. Since

cyclopropanone Cyclopropanone is an organic compound with molecular formula (CH2)2CO consisting of a cyclopropane carbon framework with a ketone functional group. The parent compound is labile, being highly sensitive toward even weak nucleophiles. Surrogates ...

is highly sensitive, cyclobutanone is the smallest, easily handled cyclic ketone.

Preparation

The Russian chemist Nikolai Kischner first prepared cyclobutanone in 1905. He synthesized cyclobutanone in a low yield from cyclobutanecarboxylic acid in several reaction steps. This process is cumbersome and inefficient by today's standards. : Cyclobutanone Formation1 V

More efficient, high-yielding syntheses have since been developed. One strategy involves degradation of five-carbon building blocks. For example, the oxidative decarboxylation of cyclobutanecarboxylic acid was improved by the use of other reagents and methods. A newer, more efficient preparation of cyclobutanone was found by P. Lipp and R. Köster in which a solution of

diazomethane Diazomethane is the chemical compound CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost ...

diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...

is reacted with

ketene In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary monovalent chemical groups (or two separate substitution sites in the same molecule). The name may also refer to the specific compound ethen ...

. This reaction is based on a ring expansion of the

intermediate initially formed, wherein molecular nitrogen is split off. The reaction mechanism was confirmed by a reaction using ¹⁴C-labeled diazomethane. : Cyclobutane Synthesis V

Another synthesis of cyclobutanone involves lithium-catalyzed rearrangement of oxaspiropentane, which is formed by

epoxidation In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale ...

of the easily accessible

methylenecyclopropane Methylenecyclopropane is an organic compound with the formula (CH2)2CCH2. It is a colourless easily condensed gas that is used as a reagent in organic synthesis. Synthesis Methylenecyclopropane can be synthesised via an intramolecular cyclisatio ...

. :

Cyclobutanone can also be prepared in a two step procedure by dialkylation of

1,3-dithiane A dithiane is a heterocyclic compound composed of a cyclohexane core structure wherein two methylene bridges (-- units) are replaced by sulfur centres. The three isomeric parent heterocycles are 1,2-dithiane, 1,3-dithiane and 1,4-dithiane. 1 ...

with 1-bromo-3-chloropropane followed by deprotection to the ketone with

mercuric chloride Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is a ...

(HgCl₂) and cadmium carbonate (CdCO₃).

Reactions

At about 350 °C, cyclobutanone decomposes into ethylene and

. The

activation energy In chemistry and physics, activation energy is the minimum amount of energy that must be provided for compounds to result in a chemical reaction. The activation energy (''E''a) of a reaction is measured in joules per mole (J/mol), kilojoules p ...

for this +2cycloelimination is 52 kcal/mol. The reverse reaction, the +2

cycloaddition In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity". T ...

of ketene and ethylene, has never been observed. : Cyclobutanone Decomposition V

References

{{reflist 4 Cyclobutanes Substances discovered in the 1900s

Preparation

Reactions

See also

References