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Diagram showing the ortho, meta and para positions relative to a substituent X on a benzene ring. Electron donating groups are typically divided into three levels of activating ability (The "extreme" category can be seen as "strong".) Electron withdrawing groups are assigned to similar groupings.
In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6H5, and is often represented by the symbol Ph (archaically φ) or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen, which may be replaced by some other element or compound to serve as a ...
Ipso-substitution describes two substituents sharing the same ring position in an intermediate compound in an electrophilic aromatic substitution. Trimethylsilyl, tert-butyl, and isopropyl groups can form stable carbocations, hence are ipso directing groups. Meso-substitution refers to the substituents occupying a benzylic position.
There are three main ortho effects in substituted benzene compounds: Steric hindrance forces cause substitution of a chemical group in the ortho position of benzoic acids become stronger acids. Steric inhibition of protonation caused by substitution of anilines to become weaker bases, compared to substitution of isomers in the meta and para ...
As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks and chromosomal damage, hence is teratogenic and mutagenic. Benzene causes cancer in animals including humans.
Heteroarenes are aromatic compounds, where at least one methine or vinylene (-C= or -CH=CH-) group is replaced by a heteroatom: oxygen, nitrogen, or sulfur. [3] Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one ...
Both the regioselectivity—the diverse arene substitution patterns—and the speed of an electrophilic aromatic substitution are affected by the substituents already attached to the benzene ring. In terms of regioselectivity, some groups promote substitution at the ortho or para positions, whereas other groups favor substitution at the meta ...
Structures of some fundamental cyclophanes: [n]-paracyclophanes (left), [n]-metacyclophanes, and [n.n]paracyclophanes (right). In organic chemistry, a cyclophane is a hydrocarbon consisting of an aromatic unit (typically a benzene ring) and a chain that forms a bridge between two non-adjacent positions of the aromatic ring.