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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]
As a result, while anthracene reacts with maleic acid, phenanthrene does not, and triphenylene is the most stable species of these three. [ 1 ] Three Clar structures with an increasing number of π-sextets: anthracene (on the left), phenanthrene (in the middle), and triphenylene (on the right).
A Polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings.Most are produced by the incomplete combustion of organic matter— by engine exhaust fumes, tobacco, incinerators, in roasted meats and cereals, [1] or when biomass burns at lower temperatures as in forest fires.
Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C 14 H 10, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the production of the red dye alizarin and other dyes. Anthracene is colorless but exhibits a blue (400–500 nm peak) fluorescence under ultraviolet radiation. [13]
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.
At least three plausible mechanisms for the Elbs reaction have been suggested. [5] The first mechanism, suggested by Fieser, begins with a heat-induced cyclisation of the benzophenone, followed by a [1,3]-hydride shift to give the compound . A dehydration reaction then affords the polyaromatic. Fieser's mechanism
The most widely used synthetic route to DBA utilizes electrophilic borylation chemistry as the key transformation, [6] [7] which dates to 1969 from Seibert et al. [8] and 1998 from Eisch et al. [9] Starting with the commercially available chemical 1,2-dibromobenzene, lithium-halogen exchange [10] followed by silylation yields 1,2-bis(trimethylsilyl) benzene as the intermediate.
The reaction of anthracene with N-methylformanilide, also using phosphorus oxychloride, gives 9-anthracenecarboxaldehyde: N -Methylformanilide and anthracene and phosphorus oxychloride In general, the electron-rich arene ( 3 ) must be much more active than benzene for the reaction to proceed; phenols or anilines are good substrates.