Aromatic ring currentAn aromatic ring current is an effect observed in aromaticmolecules such as benzene and naphthalene. If a magnetic field is directed perpendicular to the plane of the aromatic system, a ring current is induced in the delocalized π electrons of the aromatic ring.
Aromatic compoundAromatic compounds or arenes are organic compounds "with a chemistry typified by benzene" and "cyclically conjugated." The word "aromatic" originates from the past grouping of molecules based on odor, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation to their odor. Aromatic compounds are now defined as cyclic compounds satisfying Hückel's rule.
CyclobutadieneNames Preferred IUPAC nameCyclobuta-1,3-dieneOther names 1,3-CyclobutadieneCyclobutadiene[4]AnnuleneIdentifiers CAS Number1120-53-23D model (JSmol)Interactive imageChEBICHEBI:33657ChemSpider120626PubChemCID136879UNIII5G5583N4FCompTox Dashboard(EPA)DTXSID00149807InChIInChI=1S/C4H4/c1-2-4-3-1/h1-4HKey: HWEQKSVYKBUIIK-UHFFFAOYSA-NInChI=1/C4H4/c1-2-4-3-1/h1-4HKey: HWEQKSVYKBUIIK-UHFFFAOYAISMILESC1=CC=C1Properties Chemical formulaC4H4Molar mass52.076 g·mol Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).Yverify ( ?)
Hückel's ruleIn organic chemistry, Hückel's rule predicts that a planarringmolecule will have aromatic properties if it has (4n + 2)π-electrons, where n is a non-negative integer. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. The succinct expression as the 4n + 2 rule has been attributed to W. v. E. Doering (1951), although several authors were using this form at around the same time.
AromaticityIn organic chemistry, aromaticity is a chemical property describing the way in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone. The earliest use of the term was in an article by August Wilhelm Hofmann in 1855. There is no general relationship between aromaticity as a chemical property and the olfactory properties of such compounds.
BiphenyleneBiphenylene is an organic compound with the formula (C6H4)2. It is a pale, yellowish solid with a hay-like odor. Despite its unusual structure, it behaves like a traditional polycyclic aromatic hydrocarbon. BondingBiphenylene is a polycyclic hydrocarbon, composed of two benzene rings joined by two bridging bonds (as opposed to a normal ring fusion), thus forming a 6–4–6 arene system.
PentalenePentalene is a polycyclic hydrocarbon composed of two fused cyclopentadiene rings. It has chemical formulaC8H6. It is antiaromatic, because it has 4nπ electrons where n is any integer. For this reason it dimerizes even at temperatures as low as −100 °C. The derivative 1,3,5-tri-tert-butylpentalene was synthesized in 1973. Because of the tert-butyl substituents this compound is thermally stable.
CyclooctatetraeneNames Preferred IUPAC nameCycloocta-1,3,5,7-tetraeneOther names [8]Annulene(1Z,3Z,5Z,7Z)-Cycloocta-1,3,5,7-tetraene1,3,5,7-CyclooctatetraeneCOTIdentifiers CAS Number629-20-93D model (JSmol)Interactive imageChEBICHEBI:47034ChemSpider553448ECHA InfoCard100.010.074EC Number211-080-3PubChemCID637866UNIIAJ19R479CQCompTox Dashboard(EPA)DTXSID9060867InChIInChI=1S/C8H8/c1-2-4-6-8-7-5-3-1/h1-8H/b2-1-,3-1-,4-2-,5-3-,6-4-,7-5-,8-6-,8-7-Key: KDUIUFJBNGTBMD-BONZMOEMSA-NInChI=1/C8H8/c1-2-4-6-8-7-5-3-1/h1-8H/b2-1-,3-1-,4-2-,5-3-,6-4-,7-5-,8-6-,8-7-Key: KDUIUFJBNGTBMD-BONZMOEMBRSMILESC1=C\C=C/C=C\C=C1Properties Chemical formulaC8H8Molar mass104.15 g/mol Appearance Clear yellow Density0.9250 g/cm, liquid Melting point−5 to −3 °C (23 to 27 °F; 268 to 270 K) Boiling point142 to 143 °C (288 to 289 °F; 415 to 416 K) Solubility in waterimmiscible Magnetic susceptibility (χ)−53.9·10 cm/mol Hazards GHS labelling: PictogramsSignal wordDangerHazard statementsH225, H304, H315, H319, H335Precautionary statementsP210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P301+P310, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P321, P331, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501NFPA 704 (fire diamond) 330Flash point−11 °C (12 °F; 262 K) Autoignitiontemperature561 °C (1,042 °F; 834 K) Related compounds Related hydrocarbonsCyclooctaneTetraphenyleneExcept where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).Yverify ( ?)
MoleculeA molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and molecule is often used when referring to polyatomic ions.
Lone pairIn chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure. Electron pairs are therefore considered lone pairs if two electrons are paired but are not used in chemical bonding.Chemical propertyA chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any attribute that can be established only by changing a substance's chemical identity. Simply speaking, chemical properties cannot be determined just by viewing or touching the substance; the substance's internal structure must be affected greatly for its chemical properties to be investigated.
Pi bondIn chemistry, pi bonds (π bonds) are covalent chemical bonds, in which each of two lobes of an orbital on one atom overlap with two lobes of an orbital on another atom, and in which this overlap occurs laterally. Each of these atomic orbitals has an electron density of zero at a shared nodal plane that passes through the two bonded nuclei. This plane also is a nodal plane for the molecular orbital of the pi bond.*As an Amazon Associate I earn from qualifying purchases.