Cyclopropanone 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. The ...

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)₂CO consisting of a

cyclopropane Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself ...

carbon framework with a

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

. The parent compound is labile, being highly sensitive toward even weak nucleophiles. Surrogates of cyclopropanone include the

ketal In organic chemistry, an acetal is a functional group with the connectivity . Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments no ...

Preparation

Cyclopropanone has been prepared by reaction of

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 etheno ...

with

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 u ...

. These solutions are stable at −78 °C. In the presence of protic reagents such as carboxylic acids, primary and secondary amines, and alcohols, cyclopropanone converts to adducts, which are often isolatable at room temperature: :(CH₂)₂CO + X-H → (CH₂)₂C(X)(OH) (X-H = R₂N-H, HO-H, RO-H)

Structure and bonding

The C₃O atoms are coplanar. As deduced from the microwave spectrum, the H₂C-CH₂ bond length of 157.5 pm is unusually long. By contrast, the C-C bond lengths in

are 151 pm. The C=O bond length of 119 pm is short compared to the 123 pm bond length in

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

. The value of ν_C=O in the

infrared spectrum Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

is near 1815 cm⁻¹, ca. 70 cm⁻¹ higher than values for a typical ketone.

Derivatives

Cyclopropanones are intermediates in the

Favorskii rearrangement The Favorskii rearrangement is principally a rearrangement of cyclopropanones and α-halo ketones that leads to carboxylic acid derivatives. In the case of cyclic α-halo ketones, the Favorskii rearrangement constitutes a ring contraction. This ...

with cyclic ketones where

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

formation is accompanied by ring-contraction. Cyclopropanones react as 1,3-dipoles in

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 ...

s for instance with cyclic dienes such as

furan Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans. Furan is a colorless, flammable, highly ...

. An oxyallyl intermediate or valence tautomer (formed by cleavage of the C2-C3 bond) is suggested as the active intermediate or even a biradical structure (compare to the related

trimethylenemethane Trimethylenemethane (often abbreviated TMM) is a chemical compound with formula . It is a neutral free molecule with two unsatisfied valence bonds, and is therefore a highly reactive free radical. Formally, it can be viewed as an isobutylene mo ...

). : Other reactions of cyclopropanones take place through this intermediate. For instance

enantiopure In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical anti ...

(+)-''trans''-2,3-di-tert-butylcyclopropanone racemizes when heated to 80 °C. An oxyallyl intermediate is also proposed in the

photochemical Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400–7 ...

conversion of a 3,5-dihydro-4H-pyrazole-4-one with expulsion of nitrogen to an

indane Indane or indan is an organic compound with the formula C6H4(CH2)3. It is a colorless liquid hydrocarbon. It is a petrochemical, a bicyclic compound. It occurs at the level of about 0.1% in coal tar. It is usually produced by hydrogenation of ...

: : In this reaction oxyallyl intermediate A, in

chemical equilibrium In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the sy ...

with cyclopropanone B attacks the

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...

ring through its

carbocation A carbocation is an ion with a positively charged carbon atom. Among the simplest examples are the methenium , methanium and vinyl cations. Occasionally, carbocations that bear more than one positively charged carbon atom are also encountere ...

forming a transient 1,3-cyclohexadiene C (with UV trace similar to

isotoluene The isotoluenes in organic chemistry are the non-aromatic toluene isomers with an exocyclic double bond. They are of some academic interest in relation to aromaticity and isomerisation mechanisms. The three basic isotoluenes are ''ortho''-isoto ...

) followed by rearomatization. The energy difference between A and B is 5 to 7

kcal The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of o ...

/ mol (21 to 29 kJ/mol).

Coprine

The cyclopropanone derivative 1-aminocyclopropanol occurs naturally by

hydrolyzes Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

coprine Coprine is a mycotoxin. It was first isolated from Coprinopsis atramentaria, common inkcap (''Coprinopsis atramentaria''). It occurs in mushrooms in the genera ''Coprinopsis'' When combined with ethanol, alcohol, it causes "Coprinus syndrome". It ...

, a toxin in some mushrooms. 1-Aminocyclopropanol is an inhibitor of the enzyme

acetaldehyde dehydrogenase Acetaldehyde dehydrogenases () are dehydrogenase enzymes which catalyze the conversion of acetaldehyde into acetic acid. The oxidation of acetaldehyde to acetate can be summarized as follows: Acetaldehyde + NAD+ + Coenzyme A ↔ Acetyl-CoA + NA ...

References

{{reflist 3 Cyclopropanes

Preparation

Structure and bonding

Derivatives

Coprine

See also

References