organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, an alicyclic compound contains one or more all-carbon rings which may be either saturated or unsaturated, but do not have

aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...

character. Alicyclic compounds may have one or more

aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated (in which all ...

side chains attached.

Cycloalkanes

The simplest alicyclic compounds are the monocyclic

cycloalkane In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the ring (chemistry), monocyclic Saturated and unsaturated compounds, saturated hydrocarbons. In other words, a cycloalkane consists only of hydroge ...

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

cyclobutane Cyclobutane is a cycloalkane and organic compound with the formula (CH2)4. Cyclobutane is a colourless gas and is commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commerc ...

cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic compound, alicyclic hydrocarbon with chemical formula C5H10, C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and ...

cyclohexane Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...

cycloheptane Cycloheptane, also known as Suberane, is an Chemical compound, organic compound, which belongs to the group of cycloalkanes. The compound can occur in different Rotamer, conformers. Production Cycloheptane occurs naturally in petroleum and can b ...

, cyclooctane, and so on.

Bicyclic A bicyclic molecule () is a molecule that features two joined rings. Bicyclic structures occur widely, for example in many biologically important molecules like α-thujene and camphor. A bicyclic compound can be carbocyclic (all of the ring ...

alkanes include decalin, housane, and norbornane. Polycyclic alkanes include

cubane Cubane is a synthetic hydrocarbon compound with the Chemical formula, formula . It consists of eight carbon atoms arranged at the corners of a Cube (geometry), cube, with one hydrogen atom attached to each carbon atom. A solid crystalline substanc ...

, basketane, and tetrahedrane.

Spiro compound In organic chemistry, spiro compounds are Organic compound, compounds that have at least two Cyclic compound, molecular rings sharing one common atom. Simple spiro compounds are bicyclic (having just two rings). The presence of only one common at ...

s have two or more rings that are connected through only one carbon atom. The mode of ring-closing in the formation of many alicyclic compounds can be predicted by Baldwin's rules. Otto Wallach, a German chemist, received the 1910

Nobel Prize in Chemistry The Nobel Prize in Chemistry () is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outst ...

for his work on alicyclic compounds.

Cycloalkenes

Monocyclic

cycloalkene In organic chemistry, a cycloalkene or cycloolefin is a type of alkene hydrocarbon which contains a closed Ring (chemistry), ring of carbon atoms and either one or more double bonds, but has no Aromaticity, aromatic character. Some cycloalkenes, ...

s are cyclopropene, cyclobutene,

cyclopentene Cyclopentene is a chemical compound with the formula . It is a colorless liquid with a petrol-like odor. It has few applications, and thus is mainly used as a minor component of gasoline, present in concentrations of less than 1%. It is one of t ...

cyclohexene Cyclohexene is a hydrocarbon with the formula . It is a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an chemical intermediate, intermediate in the commercial synthesis of nylon. Prod ...

, cycloheptene, cyclooctene, and so on. Bicyclic alkenes include norbornene and norbornadiene. Two more examples are shown below, methylenecyclohexane on the left and 1-methylcyclohexene on the right:

An exocyclic group is always shown outside the ring structure, take for instance the exocyclic double bond of the former molecule. Isotoluenes are a prominent class of compounds with exocyclic double bonds. The placement of double bonds in many alicyclic compounds can be predicted with Bredt's rule.

References

{{Authority control Organic compounds Cyclic compounds