76115-96-3Relevant academic research and scientific papers
Active and deactive modes of modified montmorillonite in p-cresol acylation
Venkatesha,Chandrashekara,Jai Prakash,Bhat
, p. 181 - 187 (2014)
para-Toluene sulphonic acid (p-TSA)-treated montmorillonite clay used as heterogeneous catalyst in acylation of para-cresol (PC) with aliphatic carboxylic acids. Reactions were studied under microwave and conventional modes of heating and reaction conditions were optimized by varying mole ratio, temperature, amount of catalyst and reaction time. Under optimized conditions the reaction was carried out involving p-cresol and decanoic acid. The reaction involved two steps, O-acylation involving ester formation followed by the Fries rearrangement involving C-acylation resulting in ketone product. Microwave heating mode showed higher conversion and the catalytic activity almost retained in repeated use. On the other hand the catalytic activity dropped by more than 50% in the case of conventional heating indicating rapid deactivation. A change in the color of the used catalyst was more intense in the case of conventional than in the microwave heating. Used catalysts were characterized for surface area and pore volume by BET technique, acidity by FTIR spectroscopy and amount of coke by TGA. Further investigations on the catalyst used in conventional heating revealed that the deactivation occurred during the O-acylation and not in the subsequent Fries rearrangement. However, the catalyst in the microwave irradiated reaction, exhibited a retarded rate of formation of coke precursors on the surface during O-acylation, thus preventing any decrease in catalytic activity. Present study indicates that the technique chosen for heating the reaction medium plays an important role in suppressing deactivation.
The active site accessibility aspect of montmorillonite for ketone yield in ester rearrangement
Venkatesha,Jai Prakash,Bhat
, p. 1629 - 1637 (2015/04/27)
The removal of Al from the octahedral layer of montmorillonite by organic acid treatment results in increased microporosity generating a material with different surface features from the virgin clay. The micropores thus generated are found to be responsible for ester to ketone transformation. Various parameters of the newly generated pores such as the pore diameter, pore structure, pore volumes and acidity by pyridine-FTIR were evaluated with respect to ester to ketone formation. The best correlation was found between the volume accessibility factors (VAF) and the ketone yield. The VAF reflects the extent of volume space available around the acid site for the reactant to orient in a specific way for the transformation to occur within the pore to form a specific product. This acid site accessibility aspect was further verified by extending to micropores with large VAF generated by treatment with phenoldisulfonic acid (PDSA).
Microwave-induced deactivation-free catalytic activity of BEA zeolite in acylation reactions
Chandra Shekara,Jai Prakash,Bhat
scheme or table, p. 101 - 107 (2012/07/14)
Solventless liquid-phase acylation of p-cresol with different aliphatic carboxylic acids like acetic, propionic, butyric, hexanoic, octanoic, and decanoic acids was investigated over BEA zeolite under conventional as well as microwave heating. An unanticipated huge difference in activity was observed between two modes of heating. Under conventional heating, conversion of all the acids was less than 20%, while under microwave heating, the conversion was in the range of 50-80%. Ester formed through O-acylation and ortho-hydroxyketone formed through Fries rearrangement of the ester were the only products. Conversion of carboxylic acid increased with chain length up to hexanoic acid and then it showed a decrease in the trend. With all the acids, O-acylation occurred rapidly followed by slow conversion to ortho-hydroxyketone. The ketone/ester ratio increased with catalyst amount, temperature, and reaction time. Used catalyst samples were characterized by TGA, XRD, and IR studies to understand lower activity and deactivation behavior under conventional heating. The results showed absence of coke precursor/coke on the catalyst used in microwave-irradiated reactions in contrast to catalyst used in conventionally heated ones. Higher yield in the case of microwave-assisted reactions is attributed to the prevention of coke precursor/coke on the active sites by microwaves.
Synthesis, Spectral Data and Extraction of Copper by 1-(2'-Hydroxy-5'-alkylphenyl)-1-alkanone Oximes
Krzyzanowska, Ewa,Olszanowski, A.,Juskowiak, M.
, p. 617 - 630 (2007/10/02)
1-(2'-Hydroxy-5'-alkylphenyl)-1-ethanone oximes with a normal alkyl group containing 2 to 12 carbon atoms and 1-(2'-hydroxy-5'-methylphenyl)-1-alkanone oximes containing 1 to 11 carbon atoms in the hydrocarbon chain were synthesized.Spectral data (u.v., i.r., n.m.r. and 13C) of oximes are reported.Four of these oximes were used for copper extraction from acidic solution.The results obtained indicate, that these oximes are better extractants than alkyl derivatives of 2-hydroxybenzophenone oximes.
Novel extractants for the recovery of palladium
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, (2008/06/13)
Novel ortho alkoxy substituted phenyl oxime compounds which are useful for selectively separating and recovering palladium from aqueous compositions and mixtures containing palladium and other metals.
Benzopyrones. Part 16. Synthesis of 3-Alkyl-4-oxochromen-2-carboxylic acids, 3-Alkyl-2-methylchromen-4-ones and Related Compounds
Buggy, Thomas,Ellis, Gwynn P.
, p. 3875 - 3887 (2007/10/02)
Routes to chromen-4-ones substituted at C-3 with a long alkyl chain have been investigated and the compounds synthesized include those with 2-methyl and 2-carboxylic acid groups. 7-(7-Hydroxy-2-methyl-4-oxochromen-3-yl)heptanoic acid and its ester have al
