In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile.
Tetrahedrane is a hypothetical platonic hydrocarbon with chemical formula C4H4 and a tetrahedral structure. The molecule would be subject to considerable angle strain and has not been synthesized as of 2023. However, a number of derivatives have been prepared. In a more general sense, the term tetrahedranes is used to describe a class of molecules and ions with related structure, e.g. white phosphorus.
In chemistry, a nitrene or imene is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and univalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore considered an electrophile due to the unsatisfied octet. A nitrene is a reactive intermediate and is involved in many chemical reactions. The simplest nitrene, HN, is called imidogen, and that term is sometimes used as a synonym for the nitrene class.
In chemistry, a phosphoric acid, in the general sense, is a phosphorus oxoacid in which each phosphorus (P) atom is in the oxidation state +5, and is bonded to four oxygen (O) atoms, one of them through a double bond, arranged as the corners of a tetrahedron. Two or more of these PO4 tetrahedra may be connected by shared single-bonded oxygens, forming linear or branched chains, cycles, or more complex structures. The single-bonded oxygen atoms that are not shared are completed with acidic hydrogen atoms. The general formula of a phosphoric acid is Hn+2−2xPnO3n+1−x, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure, between 0 and n + 2/2.
Carbon suboxide, or tricarbon dioxide, is an organic, oxygen-containing chemical compound with formula C3O2 and structure O=C=C=C=O. Its four cumulative double bonds make it a cumulene. It is one of the stable members of the series of linear oxocarbons O=Cn=O, which also includes carbon dioxide and pentacarbon dioxide. Although if carefully purified it can exist at room temperature in the dark without decomposing, it will polymerize under certain conditions.
Meldrum's acid or 2,2-dimethyl-1,3-dioxane-4,6-dione is an organic compound with formula C6H8O4. Its molecule has a heterocyclic core with four carbon and two oxygen atoms; the formula can also be written as [−O−(C 2)−O−(C=O)−(CH2)−(C=O)−].
In organic chemistry, hyperconjugation refers to the delocalization of electrons with the participation of bonds of primarily σ-character. Usually, hyperconjugation involves the interaction of the electrons in a sigma (σ) orbital with an adjacent unpopulated non-bonding p or antibonding σ* or π* orbitals to give a pair of extended molecular orbitals. However, sometimes, low-lying antibonding σ* orbitals may also interact with filled orbitals of lone pair character (n) in what is termed negative hyperconjugation. Increased electron delocalization associated with hyperconjugation increases the stability of the system. In particular, the new orbital with bonding character is stabilized, resulting in an overall stabilization of the molecule. Only electrons in bonds that are in the β position can have this sort of direct stabilizing effect — donating from a sigma bond on an atom to an orbital in another atom directly attached to it. However, extended versions of hyperconjugation can be important as well. The Baker–Nathan effect, sometimes used synonymously for hyperconjugation, is a specific application of it to certain chemical reactions or types of structures.
A polyyne is any organic compound with alternating single and triple bonds; that is, a series of consecutive alkynes, (−C≡C−)n with n greater than 1. These compounds are also called polyacetylenes, especially in the natural products and chemical ecology literature, even though this nomenclature more properly refers to acetylene polymers composed of alternating single and double bonds (−CR=CR′−)n with n greater than 1. They are also sometimes referred to as oligoynes, or carbinoids after "carbyne" (−C≡C−)∞, the hypothetical allotrope of carbon that would be the ultimate member of the series. The synthesis of this substance has been claimed several times since the 1960s, but those reports have been disputed. Indeed, the substances identified as short chains of "carbyne" in many early organic synthesis attempts would be called polyynes today.
A persistent carbene is an organic molecule whose natural resonance structure has a carbon atom with incomplete octet, but does not exhibit the tremendous instability typically associated with such moieties. The best-known examples and by far largest subgroup are the N-heterocyclic carbenes (NHC), in which nitrogen atoms flank the formal carbene.
Homoaromaticity, in organic chemistry, refers to a special case of aromaticity in which conjugation is interrupted by a single sp3 hybridized carbon atom. Although this sp3 center disrupts the continuous overlap of p-orbitals, traditionally thought to be a requirement for aromaticity, considerable thermodynamic stability and many of the spectroscopic, magnetic, and chemical properties associated with aromatic compounds are still observed for such compounds. This formal discontinuity is apparently bridged by p-orbital overlap, maintaining a contiguous cycle of π electrons that is responsible for this preserved chemical stability.
Carbon trioxide (CO3) is an unstable oxide of carbon (an oxocarbon). The possible isomers of carbon trioxide include ones with molecular symmetry point groups Cs, D3h, and C2v. The C2v state, consisting of a dioxirane, has been shown to be the ground state of the molecule. Carbon trioxide should not be confused with the stable carbonate ion (CO2−
3).
[n]Radialenes are alicyclic organic compounds containing n cross-conjugated exocyclic double bonds. The double bonds are commonly alkene groups but those with a carbonyl (C=O) group are also called radialenes. For some members the unsubstituted parent radialenes are elusive but many substituted derivatives are known.
A boronic acid is an organic compound related to boric acid in which one of the three hydroxyl groups is replaced by an alkyl or aryl group. As a compound containing a carbon–boron bond, members of this class thus belong to the larger class of organoboranes.
Linear acetylenic carbon (LAC), also known as carbyne or Linear Carbon Chain (LCC), is an allotrope of carbon that has the chemical structure (−C≡C−)n as a repeat unit, with alternating single and triple bonds. It would thus be the ultimate member of the polyyne family.
In chemistry, an oxocarbon or oxide of carbon is a chemical compound consisting only of carbon and oxygen. The simplest and most common oxocarbons are carbon monoxide (CO) and carbon dioxide. Many other stable or metastable oxides of carbon are known, but they are rarely encountered, such as carbon suboxide and mellitic anhydride.
In organic chemistry, a cyclo[n]carbon is a chemical compound consisting solely of a number n of carbon atoms covalently linked in a ring. Since the compounds are composed only of carbon atoms, they are allotropes of carbon. Possible bonding patterns include all double bonds or alternating single bonds and triple bonds.
Formic anhydride, also called methanoic anhydride, is an organic compound with the chemical formula C
2H
2O
3 and a structural formula of (H(C=O)−)2O. It can be viewed as the anhydride of formic acid (HCOOH).
N-Hydroxyphthalimide is the organic compound with the formula C6H4(CO)2NOH. A white or yellow solid, it is a derivative of phthalimide. The compound is as a catalyst in the synthesis of other organic compounds. It is soluble in water and organic solvents such as acetic acid, ethyl acetate and acetonitrile.
Tricarbon monoxide C3O is a reactive radical oxocarbon molecule found in space, and which can be made as a transient substance in the laboratory. It can be trapped in an inert gas matrix or made as a short lived gas. C3O can be classified as a ketene or an oxocumulene a kind of heterocumulene.
Cyclooctadeca-1,3,5,7,9,11,13,15,17-nonayne or cyclo[18]carbon is an allotrope of carbon with molecular formula C
18. The molecule is a ring of eighteen carbon atoms, connected by alternating triple and single bonds; thus, it is a polyyne and a cyclocarbon.
