Arenes, reactions

Haloarenes have been found to undergo nucleopilic substitution when irradiated with the triphenyl stannyl anion46, reacting via a radical S l mechanism. In many cases the reaction will only occur under photochemical conditions. The reaction is found to proceed with chloro- and bromo-substituted arenes, but not iodo-compounds. The anion is produced either by treatment of triphenyltin chloride or hexaphenylditin with sodium metal in liquid ammonia, and will react with a wide variety of arenes (reaction 30). 

Diarenemanganese cations have not been formed by the metal atom route, but condensation of arenes, cyclopentadiene, and manganese gives low yields of (arene) Mn(C5H5). As cyclopentadiene does not react with manganese atoms, a primary manganese-arene reaction is postulated (131, 140) (see Section III,A,3). 

As yet 20-electron diareneiron compounds have not been isolated as pure crystalline solids from iron vapor-arene reactions. However, infrared studies show that dibenzene-, ditoluene-, and dimesityleneiron are formed at low temperatures and decompose below -40°C (76). The... 

Nitration of arenes. Reaction of 1-naphthol with CAN in acetic acid results in 2,4- and 4,6-dinitro derivatives. The reaction with CAN absorbed on silica gel results in 2-nitro- and 4-nitro-l-naphthol in 42 and 38% yield, respectively. Polynuclear arenes are not oxidized to quinones by CAN supported on silica but are converted mainly into mononitro derivatives. Thus phenanthrene is converted into 2-nitrophenanthrene (45% yield) and 3-nitrophenanthrene (28% yield).1... 

Interaction of Metal Atoms and Arenes Reaction of V Atoms and Benzotrifluoride [531]... 

Still another route for selective formylation makes use of the tricarbonyl-chromium complexes of calix[4]arenes. Reaction of the tetrapropyl ether of 4 with Cr(CO)3 produces a complex in which a Cr(CO)3 moiety is associated with a single aromatic residue of the calixarene. Treatment of the complex with BuLi and then D2O, Mel, or DMF followed by decomplexation with I2 yields mono-substituted calix[4]arenes carrying D at a p- or m-position. Me at a p-position, and CHO at a p-position, respectively." ... 

Benzenoid aromatic compounds or arenes have tremendous importanee in academic and industrial chemical applications. Of the circa 10 million compounds that are known today, about three millions are arenes. Reactions involving arenes represent key steps in fundamental synthesis, especially in the pharma, agrochemical, and polymer fields. Arene compounds are also widely used as starting materials to obtain dyes, perfumes, explosives, preservatives, etc. New applications include sectors such as functional materials, organic electronics, and molecular machines. 

The crown catalyzed phase transfer of acetate ion into a nonpolar medium followed by reaction with aryldiazonium ion has also been shown to be an effective and mild method for the generation of aryl radicals [21 ]. Radicals thus generated can be reacted with deuteriochloroform or chloroform to yield deuterio- or protio-arenes. Reaction with bromotrichloromethane leads to the bromoarene and the reaction in benzene solution leads to unsymmetrical biphenyls in good yield [22]. These three processes are formulated in equation 15.7. 

The main mechanism for arene reactions is electrophilic substitution. This enables arenes to retain their delocalised n electrons. Hydrogen atoms on the benzene ring may be replaced by a variety of other atoms or groups, including halogen atoms and nitro (—NO2) groups, as well as alkyl or acyl groups in Friedel-Crafts reactions. 

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