Montmorillonite effect

Schnitzer, M., and Kodama, H. (1966). Montmorillonite Effect of pH on its adsorption of a soil humic compound. Science 153,70-71. 

Abollino, O., M. Aceto, M. Malandrino, C. Sarzanini, and E. Mentasti. 2003. Adsorption of heavy metals on Na-montmorillonite Effect of pH and organic substances. Water Res. 37 1619-1627. 

Add activation of montmorillonite Effect on structural and catalytic properties... 

Narayanan, S. and Deshpande, K. 1998. Acid activation of montmorillonite Effect on structural and catalytic properties. Studies in Surface Science and Catalysis 113 773-778. 

Heinz, H., Vaia, R. A., Rrishnamoorti, R., and Farmer, B. L. 2007. Self-assembly of alkylam-monium chains on montmorillonite Effect of chain length, headgroup structure, and cation exchange capacity. Chemistry cf Materials 19 59-68. 

Pozsgay A, Fi ater T, Szazdi L, Muller P, Sajo I and Pukauszky B (2004) Gallery structure and exfoliation of organophilized montmorillonite Effect on composite properties, Europ Polym J 40 27-36. 

Di Xu, Xiang Zhou, Xiangke Wang. Adsorption and desorption of Ni2+ on Na-montmorillonite Effect of pH, ionic strength, fiilvic acid, humic acid and addition secpiesices. Applied Clay Science. 2008,39,133-141. 

Reductive carbonylation of nitro compounds is catalyzed by various Pd catalysts. Phenyl isocyanate (93) is produced by the PdCl2-catalyzed reductive carbonylation (deoxygenation) of nitrobenzene with CO, probably via nitrene formation. Extensive studies have been carried out to develop the phosgene-free commercial process for phenyl isocyanate production from nitroben-zene[76]. Effects of various additives such as phenanthroline have been stu-died[77-79]. The co-catalysts of montmorillonite-bipyridylpalladium acetate and Ru3(CO) 2 are used for the reductive carbonylation oLnitroarenes[80,81]. Extensive studies on the reaction in alcohol to form the A -phenylurethane 94 have also been carried out[82-87]. Reaction of nitrobenzene with CO in the presence of aniline affords diphenylurea (95)[88]. 

Clays composed of attapulgite, montmorillonite, and kaoHnite are used for pesticides in finely pulverized or granular form. Granular formulations are reportedly less expensive, more easily handled, reduce loss caused by wind drift, and produce a more effective coverage. 

The oxidation has also been accomplished with Claycop (montmorillonite K-10 clay supported cupric nitrate). The reaction of 96 to 102 was complete in 1.5-7 h with 81-93% yields. The time can be reduced to 5-10 minutes using ultrasound with minimal effect on yields. The major limitation of this protocol was the observation that only R = aryl gave product. Oxidation of 4-alkyl substituents was inert to these conditions with recovery of starting 96. 

The diagenetic effects are related to the alteration of rock mineral, shales in particular. Under certain conditions, montmorillonite clays change to illites, chlorites and kaolinites. The water of hydration that desorbs in the form of free water occupies a larger volume. This volume increase will cause abnormal pressures if the water cannot escape. 

Fewer controlled experiments have been carried out for purely aquatic systems. Montmorillonite complexes with benzylamine at concentrations below 200 pg/L decreased the extent of mineralization in lake-water samples, although a similar effect was not noted with benzoate (Snbba-Rao and Alexander 1982). Even in apparently simple systems, general conclusions cannot therefore be drawn even for two structurally similar aromatic compounds, both of which are readily degradable nnder normal circumstances in the dissolved state. 

This equation shows that activity of Ca + is related to pH, concentration of H2CO3 and temperature. Because pH is related to the concentration of Cl for the equilibrium curves 1 and 2 in Fig. 2.14, the relationship between the concentrations of Ca " " and Cl" can be derived for calcite-albite-sericite-K-feldspar-quartz equilibrium (curves 4 and 7 in Fig. 2.14) and calcite-albite-sericite-Na-montmorillonite-quartz equilibrium (curves 5 and 8 in Fig. 2.14) with constant w2h2C03- The range of zh2C03 in the solution in equilibrium with calcite is assumed to be 10 to 10 . The other equilibrium curves for the assemblage including Ca minerals are also drawn (Fig. 2.14). These assemblages are wairakite-albite-sericite-K-feldspar-quartz (curve 3), Ca-montmotillonite-albite-sericite-Na-montmorillonite-quartz (curve 6), Ca-montmorillonite-albite-sericite-K-feldspar-quartz (curve 9) and anhydrite (curve 10). The effect of solid solution on the equilibrium curves is not considered because of the lack of thermochemical data of solid solution. 

E. Haque. Physicochemical interactions between montmorillonite and polymerizing systems Effect on particle-reinforced composites. PhD thesis. Rice Univ, 1986. 

The montmorillonite KlO-catalyzed aza-Diels-Alder reaction of Danishefsky s diene with aldimines, generated in situ from aliphatic aldehydes and p-anisidine, proceeded smoothly in H20 or in aqueous CH3CN to afford 2-substituted 2,3-dihydro-4-pyridones in excellent yields (Eq. 12.47).115 Also, complex [(PPh3)Ag(CBiiH6Br6)] was shown to be an effective and selective catalyst (0.1 mol% loading) for a hetero-Diels-Alder reaction with Danishefsky s diene and the reaction showed a striking dependence on the presence of trace amounts of... 

Clay materials show a different behavior. They are either cation-poor or cation-rich sheet silicates. They can swell by taking up varying amounts of water between the sheets. If the intercalated cations are hydrated as in montmorillonite, they act as cation exchangers. Montmorillonite, especially when it has intercalated Ca2+ ions, has thixotropic properties and is used to seal up drill holes. The effect is due to the charge distribution on... 

Selective removal of one isopropylidene group from a diacetal may be achieved by a variety of procedures, most of them involving protic or Lewis acids.100 Particularly common is the hydrolysis of the acetal engaging of the primary position of di-O-isopropylidene derivatives. Bhaskar et al,101 studied the selective deprotection of di-O-isopropylidene acetals derived from D-glucose, D-xylose, and D-mannose, using acid zeolites and montmorillonite K-10. When 102 was submitted to acid hydrolysis in aqueous methanol, the best yields (85—96%) for the monoacetal 105 were obtained when H-beta and HZSM-5 zeolites were employed as catalysts (Scheme 24, Table IV). HY zeolite proved to be ineffective, whereas the yield obtained for the montmorillonite K-10-catalyzed reaction was low (22%). The zeolites found most effective were then used for the hydrolysis of the diacetal 103 and 104, providing excellent yields for the desired corresponding monoacetals 106 and 107. 

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