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For example, potassium permanganate dissolves in benzene in the presence of 18-crown-6, giving the so-called "purple benzene", which can be used to oxidize diverse organic compounds. [1] Various substitution reactions are also accelerated in the presence of 18-crown-6, which suppresses ion-pairing. [10] The anions thereby become naked nucleophiles.
Benzene can be easily converted to chlorobenzene by nucleophilic aromatic substitution via a benzyne intermediate. [1] It is treated with aqueous sodium hydroxide at 350 °C and 300 bar or molten sodium hydroxide at 350 °C to convert it to sodium phenoxide, which yields phenol upon acidification. [2]
The radical mechanism of the Sandmeyer reaction is supported by the detection of biaryl byproducts. [8] The substitution of the aromatic diazo group with a halogen or pseudohalogen is initiated by a one-electron transfer mechanism catalyzed by copper(I) to form an aryl radical with loss of nitrogen gas.
The Buchner ring expansion reaction was first used in 1885 by Eduard Buchner and Theodor Curtius [1] [2] who prepared a carbene from ethyl diazoacetate for addition to benzene using both thermal and photochemical pathways in the synthesis of cycloheptatriene derivatives. The resulting product was a mixture of four isomeric carboxylic acids ...
Thus, synthesis of benzaldehyde through the Friedel–Crafts pathway requires that formyl chloride be synthesized in situ. This is accomplished by the Gattermann-Koch reaction, accomplished by treating benzene with carbon monoxide and hydrogen chloride under high pressure, catalyzed by a mixture of aluminium chloride and cuprous chloride ...
Aromatic nucleophilic substitution. This reaction differs from a common S N 2 reaction, because it happens at a trigonal carbon atom (sp 2 hybridization). The mechanism of S N 2 reaction does not occur due to steric hindrance of the benzene ring. In order to attack the C atom, the nucleophile must approach in line with the C-LG (leaving group ...
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 ...
The reaction product is a derivative of benzene. Scheme 1. Bergman cyclization. The reaction proceeds by a thermal reaction or pyrolysis (above 200 °C) forming a short-lived and very reactive para-benzyne biradical species. It will react with any hydrogen donor such as 1,4-cyclohexadiene which converts to benzene.