1791-41-9Relevant academic research and scientific papers
Re-usability of zeolites and modified clays for alkylation of cyclohexanol a contrast study
Venkatesha,Bhat,Jai Prakash
, p. 69348 - 69355 (2015/09/01)
Organic sulfonic acid treatment of montmorillonite results in micro-pores on the surface of modified clays providing access to acid sites in the interlayer. Performance of modified clay catalysts for alkylation of para-cresol with cyclohexanol were compared with microporous zeolites. Phenoldisulfonic acid treated clay catalyst showed maximum activity comparable with that of beta-zeolite. Modified clay- and zeolite-catalysts on reuse for the alkylation exhibited different behaviour. Modified clays showed same activity as in the first cycle while zeolites showed significantly reduced catalytic activities on reuse. Differences in behaviour were further investigated by characterizing the reused samples with TGA, acidity and surface measurements. Used zeolite samples showed considerable variations in acidity, surface characteristics and TGA pattern, which was attributed to the formation of coke. Absence of coke in clays and deposition of coke in zeolites is attributed to difference in their pore architecture.
Chemoselective O-Versus C-Alkylation of substituted phenols with cyclohexene over mesoporous ZSM-5
Jin, Hailian,Ansari, Mohd Bismillah,Park, Sang-Eon
, p. 184 - 190 (2014/02/14)
Chemoselective O- versus C-alkylation of substituted phenols such as phenol, p-cresol, and guaiacol with cyclohexene were investigated over various ZSM-5 catalysts with different degree of mesoporosity and external acidity such as mesoporous ZSM-5 synthesized by microwave induced assembly via electrostatic interaction between sulfonic acid, functionalized or non-functionalized ZSM-5 nanozeolites and counter cationic surfactant, and hydrothermal synthesized microporous ZSM-5 with or without sulfonic acid functionalization and surfactant. The selectivity of O- and C-alkylated products varied with different degree of mesoporosity. The selectivity of C-alkylated products increased with increasing mesopore volume and external acid sites, whereas that of O-alkylated product decreased. The mesoporous ZSM-5 synthesized under microwave via sulfonic acid functionalization showed not only the highest mesoporosity and external acid sites but also the best catalytic activity and selectivity of C-alkylated products, whereas the other ZSM-5 catalysts mainly produced O-alkylated products due to diffusion limitation of bulky product.
Highly active and selective C-alkylation of p-cresol with cyclohexanol using p-TSA treated clays under solvent free microwave irradiation
Ramesh,Jai Prakash,Bhat
scheme or table, p. 157 - 162 (2012/03/26)
The efficiency of p-TSA treated clays was probed in the alkylation of p-cresol under solvent free microwave irradiation. The different aspects of the reaction studies include variation of temperature, duration of contact between the reactants, mole ratio of cresol to cyclohexanol and the clay treated with p-TSA to different extent. The acid strength as well as reaction parameters such as temperature and time were found to be the main factors controlling the reactivity and selectivity. The reaction was carried out in the temperature range 413-443 K. Lower temperature range favoured O-alkylation and higher temperatures yielded C-alkylated p-cresol. The catalyst retained its catalytic activity even after three consecutive runs. The results obtained with clays were compared with other solid acid catalysts such as aluminium exchanged clay, hydrochloric acid treated clay and K-10.
ORTHO-ALKYLATION OF o-, m-, AND p-CRESOLS WITH CYCLOHEXENE IN THE PRESENCE OF ALUMINUM CRESOLATES
Kozlikovskii, Ya. B.,Koshchii, V. A.,Butov, S. A.,Sokolova, A. V.
, p. 1702 - 1707 (2007/10/02)
The reaction of o-, m-, and p-cresols with cyclohexene in the presence of the corresponding aluminum cresolates leads to mixtures of ethers and phenols, in which the ortho-alkylation products, formed with yields of 75-85percent, predominate.
