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Clar's rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. one with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical and physical properties. Such a resonance structure is called a Clar structure. In other words, a ...
Phenanthrene is a polycyclic aromatic hydrocarbon (PAH) with formula C 14 H 10, consisting of three fused benzene rings. It is a colorless, crystal-like solid, but can also appear yellow. Phenanthrene is used to make dyes, plastics, pesticides, explosives, and drugs. It has also been used to make bile acids, cholesterol and steroids. [3]
According to one, the relative stability of phenanthrene compared to its isomers can be adequately explained by comparing resonance stabilizations. [8] Another critic argues that the stability of phenanthrene can be attributed to more effective pi-pi overlap in the central double bond; the existence of bond paths is not questioned but the ...
ortho-Substituted substrates generally give 1-substituted phenanthrenes, unless the substituent is a good leaving group, in which case elimination to form unsubstituted phenanthrene occurs. [11] meta- Substituted substrates give mixtures of 2- and 4-substituted products. Substitution of the exocyclic double bond is well tolerated.
Chrysene is a polycyclic aromatic hydrocarbon (PAH) with the molecular formula C 18 H 12 [4] that consists of four fused benzene rings. It is a natural constituent of coal tar, from which it was first isolated and characterized.
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It has been prepared by oxidation of phenanthrene with chromic acid. [3] It is used as an artificial mediator for electron acceptor/donor in Mo/W containing formate dehydrogenase reduction of carbon dioxide to formate and vice versa. It is a better electron acceptor than the natural nicotinamide adenine dinucleotide (NAD +).
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