12.12(b)Attack by bromine at the position meta to the amino group gives a cyclohexadienyl cation intermediate in which delocalization of the nitrogen lone pair cannot participate in dispersal of the positive charge.
CyclohexeneSulfuric acidCyclohexyl cationHydrogen sulfate ion OS O2OH
or any of its resonance forms. Because of its tertiary carbocation character, this cation is more stable than the corresponding cyclohexadienyl cation intermediate from benzene. (f)Anitro substituent is deactivating and meta-directing. The most stable cyclohexadienyl cation formed in the bromination of nitrobenzene is
One way to assess the relative stabilities of these various intermediates is to examine electron delocalization in them using a resonance description. The cyclohexadienyl cations leading to o-and p-nitrotoluene have tertiary carbocation character. Each has a resonance form in which the positive charge resides on the carbon that bears the methyl group.
Cyclohexadienyl cation intermediate fast H Cl
The Pd/Hβ binary catalyst was prepared by the impregnation method and was used for the hydroalkylation of benzene to cyclohexylbenzene. The conversion of benzene and the selectivity for cyclohexylbenzene approached 24 and 88.0%, respectively, under the conditions of 2.5 MPa H2, 200°C, and 3 hr. The preferable balance between metal active sites and acidic sites in the catalyst was the key to the benzene hydroalkylation. On the basis of the relationship between reaction conditions and product distribution, the mechanism of hydroalkylation of benzene over the binary catalyst was proposed.
Cyclohexadienyl cation intermediate
To a mixture of 4-chloro benzaldehyde (1 mmol) and 5,5-dimethyl-1,3-cyclohexanedione (2 mmol) and [bmim] ClO4 (4 mmol) was added in 50 ml round bottom flask and was stirred at 100˚C on heating magnetic stirrer. The progress of the reaction was monitored by TLC After completion of the reaction the reaction mixture was cooled to room temperature and water (5 ml) was added, solid separated was filtered and product was characterized by IR, NMR, 13C-NMR and mass.
Amandine Mallen Paris Cyclohexylbenzene synthesis essay
To a mixture of aldehyde (1 mmol) and 5,5-dimethyl- 1,3-cyclohexanedione (2 mmol) and [bmim]ClO4 (4 mmol) was added in 50 ml round bottom flask and was stirred at 100˚C on heating magnetic stirrer (). The progress of the reaction was monitored by TLC after completion of the reaction the reaction mixture was cooled to room temperature and water (5 ml) was added, solid separated was filtered. The crude product was recrystallized from ethanol to give the pure product. The [bmim]ClO4 was recovered by distillation and reused 3 times.
Less stable cyclohexadienyl cation
the scission of the hydroperoxide of cyclohexylbenzene to phenol and cyclohexanone by homogeneous or heterogeneous acid catalysts characterized in that the synthesis of cyclohexylbenzene takes place in the presence of a catalytic system comprising a Y zeolite and an inorganic ligand wherein the Y zeolite has a crystalline structure with openings consisting of (12) tetrahedra and the inorganic ligand is ?-alumina, and wherein said catalytic composition is characterized by a pore volume, obtained by adding the mesoporosity and macroporosity fractions, greater than or equal to 0.7 cm /g, wherein at least 30% of said volume consists of pores with a diameter greater than 100 nanometers.
More stable cyclohexadienyl cation
the selective aerobic oxidation of cyclohexylbenzene to the corresponding hydroperoxide catalyzed by N- hydroxy-derivatives in the presence of polar solvents and c.