Organic synthesis using clay and clay-supported catalysts

Nagendrappa, Gopalpur

doi:10.1016/j.clay.2010.09.016

Cited by 216 publications

(121 citation statements)

References 97 publications

Supporting

Mentioning

114

Contrasting

Unclassified

Order By: Relevance

“…Since the catalytic affect of the clay can be attributed to the Lewis acid activity of its metallic centers (Scheme 2a), the good reactivity of the methoxy derivatives can be explained by accepting that coordination of the oxygen atom in the OMe group with cationic centers in the clay attenuates its electron-releasing effect (Scheme 2b) [40]. Another special case was that of nitrobenzaldehyde derivatives which, again unexpectedly, gave relatively low yields (entries 7,8,9,13,18,22,25,[30][31][32][33][34][35]. In this case, we propose that the lower reactivity is due to an increased activation energy associated to stabilizing interactions of the aldehyde with the clay by coordinating two of the cationic centers (Scheme 2c).…”

Section: Resultsmentioning

confidence: 99%

“…In particular, there is much interest in the use of clays as solid acid catalysts because of their desirable properties such as environmental compatibility, non-corrosive and non-toxic nature, low cost and, furthermore, because they often allow very simple isolation procedures. To summarize, heterogeneous catalysis is crucial to chemical technology, and clays in particular are finding increasing applications as catalysts [31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Montmorillonite Clay-Promoted, Solvent-Free Cross-Aldol Condensations under Focused Microwave Irradiation

2014

View full text Add to dashboard Cite

An environmentally benign, clean and general protocol was developed for the synthesis of aryl and heteroaryl trans-chalcones. This method involved solvent-free reaction conditions under microwave irradiation in the presence of a clay-based catalyst, and afforded the target compounds in good yields and short reaction times. Furthermore, the same conditions allowed the synthesis of symmetrical, diarylmethylene-α,β-unsaturated ketones from aromatic aldehydes and ketones.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Montmorillonite Clay-Promoted, Solvent-Free Cross-Aldol Condensations under Focused Microwave Irradiation

2014

View full text Add to dashboard Cite

show abstract

“…This hypothesis is consistent with the documented ability of clay minerals to catalyze condensation and polymerization reactions from a variety of substrates. [35][36][37] This effect is of particular importance, since the low-molecular weight degradation products have been shown to have a mutagenic potential 38 .At pyrolysis temperatures of 450 °C -550 °C, the 13 C NMR signal is very similar in all the materials being centered at ~ 130 pm as see in Figure 2 (g-l). The primary species produced at these temperatures have an aromatic carbon structure, in addition to some phenolic and carboxylic species observed at ~150-160 ppm and 165-180 ppm, respectively.…”

Section: Infiltrationmentioning

confidence: 93%

Mineral–Biochar Composites: Molecular Structure and Porosity

Rawal¹,

Joseph²,

Hook³

et al. 2016

Environ. Sci. Technol.

161

View full text Add to dashboard Cite

Dramatic changes in molecular structure, degradation pathway, and porosity of biochar are observed at pyrolysis temperatures ranging from 250 to 550 °C when bamboo biomass is pretreated by iron-sulfate-clay slurries (iron-clay biochar), as compared to untreated bamboo biochar. Electron microscopy analysis of the biochar reveals the infusion of mineral species into the pores of the biochar and the formation of mineral nanostructures. Quantitative 13C nuclear magnetic resonance (NMR) spectroscopy shows that the presence of the iron clay prevents degradation of the cellulosic fraction at pyrolysis temperatures of 250 °C, whereas at higher temperatures (350-550 °C), the clay promotes biomass degradation, resulting in an increase in both the concentrations of condensed aromatic, acidic, and phenolic carbon species. The porosity of the biochar, as measured by NMR cryoporosimetry, is altered by the iron-clay pretreatment. In the presence of the clay, at lower pyrolysis temperatures, the biochar develops a higher pore volume, while at higher temperature, the presence of clay causes a reduction in the biochar pore volume. The most dramatic reduction in pore volume is observed in the kaolinite-infiltrated biochar at 550 °C, which is attributed to the blocking of the mesopores (2-50 nm pore) by the nonporous metakaolinite formed from kaolinite. Disciplines Engineering | Physical Sciences and Mathematics

show abstract

“…Montmorillonite K10 (MMT K10), the major clay mineral commercially available has been used as a heterogeneous catalyst for many applications [5], [6]. There are considerable methods which can be used to modify MMT to improve its catalytic properties, such of these methods include cation exchanged.…”

Section: Introductionmentioning

confidence: 99%

Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM)

Almadani

Harun

Radzi

et al. 2018

Bull. Chem. React. Eng. Catal.

View full text Add to dashboard Cite

Clay catalyst has received much attention to replace the homogeneous catalysts in the esterification reaction to produce fatty acid methyl ester as the source of biodiesel as it is low cost, easily available, as well as environmental friendly. However, the use of unmodified clay, in particular montmorillonite K10 (MMT K10), for the esterification of fatty acids showed that the acid conversion was less than 60% and this is not preferable to the production of biodiesel. In this study, synthesis of stearic acid methyl ester using Cu 2+ -MMT K10 (Cu-MMT K10) was successfully optimized via response surface methodology (RSM) based on 3-variable of Box-Behnken design (BB). The parameters were; reaction time (5-180 minutes), reaction temperature (80-120 o C) and concentration of Cu 2+ in MMT K10 (0.25-1 M). The use of RSM in optimizing the conversion of stearic acid was successfully developed as the actual experimental conversion of stearic acid was found similar to the actual values under the optimum conditions. The model equation predicted that the following conditions would generate the maximum conversion of stearic acid (87.05 % reaction time of 62 minutes, a reaction temperature of 80 o C and catalyst used is 1.0 M Cu-MMT K10. This finding can be considered as green catalytic process as it worked at moderate reaction temperature using low cost clay catalyst with a short reaction time.

show abstract

Organic synthesis using clay and clay-supported catalysts

Cited by 216 publications

References 97 publications

Montmorillonite Clay-Promoted, Solvent-Free Cross-Aldol Condensations under Focused Microwave Irradiation

Montmorillonite Clay-Promoted, Solvent-Free Cross-Aldol Condensations under Focused Microwave Irradiation

Mineral–Biochar Composites: Molecular Structure and Porosity

Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM)

Contact Info

Product

Resources

About