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The reaction is used for the transfer of methyl and ethyl groups between benzene rings. This is of particular value in the petrochemical industry [1] to manufacture p-xylene, styrene, [2] and other aromatic compounds. Motivation for using transalkylation reactions is based on a difference in production and demand for benzene, toluene, and xylenes.
Toluene (/ ˈ t ɒ l. j u iː n /), also known as toluol (/ ˈ t ɒ l. j u. ɒ l , - ɔː l , - oʊ l / ), is a substituted aromatic hydrocarbon [ 15 ] with the chemical formula C 6 H 5 CH 3 , often abbreviated as PhCH 3 , where Ph stands for the phenyl group.
Aromatization is a chemical reaction in which an aromatic system is formed from a single nonaromatic precursor. Typically aromatization is achieved by dehydrogenation of existing cyclic compounds, illustrated by the conversion of cyclohexane into benzene.
Gattermann-Koch reaction: named after German chemists Ludwig Gattermann and Julius Arnold Koch, the Gattermann-Koch reaction is a catalyzed formylation of alkylbenzenes with carbon monoxide and hydrochloric acid. [5] Alkylbenzene sulfonation reaction: electrophilic addition of a sulfonic acid group onto the aromatic ring. [4]
The overall reaction mechanism, denoted by the Hughes–Ingold mechanistic symbol S E Ar, [3] begins with the aromatic ring attacking the electrophile E + (2a). This step leads to the formation of a positively charged and delocalized cyclohexadienyl cation, also known as an arenium ion, Wheland intermediate, or arene σ-complex (2b).
Hydrodealkylation is a chemical reaction that often involves reacting an aromatic hydrocarbon, such as toluene, in the presence of hydrogen gas to form a simpler aromatic hydrocarbon devoid of functional groups. An example is the conversion of 1,2,4-trimethylbenzene to xylene. [1]
Although, the need for sodium metal limits the functional group tolerance of the reaction, compared to more modern cyclization reactions (e.g. Yamaguchi esterification, ring-closing olefin metathesis), the acyloin condensation continues to be used in the synthesis of complex natural products for the preparation of challenging ring systems. [9]
The metabolism of o-toluidine involves many competing activating and deactivating pathways, including N-acetylation, N-oxidation, and N-hydroxylation, and ring oxidation. [22] 4-Hydroxylation and N-acetylation of toluidine are the major metabolic pathways in rats. The primary metabolism of o-toluidine takes place in the endoplasmic reticulum.