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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 used to make dyes, plastics, pesticides, explosives, and drugs. It has also been used to make bile acids, cholesterol and steroids. [3] Phenanthrene occurs naturally and also is a man-made chemical. Commonly, humans are exposed to phenanthrene through inhalation of cigarette smoke, but there are many routes of exposure.
Pyrene is a polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is C 16 H 10.This yellow-green solid is the smallest peri-fused PAH (one where the rings are fused through more than one face).
Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.
In organic chemistry, the Mallory reaction is a photochemical-cyclization–elimination reaction of diaryl-ethylene structures to form phenanthrenes and other polycyclic form polycyclic aromatic hydrocarbons and heteroaromatics. [1] [2] This name reaction is named for Frank Mallory, who discovered it while a graduate student. [3]
Benzo[c]phenanthrene is a polycyclic aromatic hydrocarbon with the chemical formula C 18 H 12. It is a white solid that is soluble in nonpolar organic solvents. It is a nonplanar molecule [1] [2] consisting of the fusion of four fused benzene rings. The compound is of mainly theoretical interest but it is environmentally occurring [3] and ...
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The analogous cyclic system appears to have even more resonance stabilized, as the negative charge can be delocalized across three carbons instead of two. However, the cyclopropenyl anion has 4 π electrons in a cyclic system and in fact has a substantially higher p K a than 1-propene because it is antiaromatic and thus destabilized. [ 3 ]