Mg-Al layered double hydroxides

The results obtained by Kuila et al. and Acharya et al. [63,64] from the EVA elastomer blended with lamellar-like Mg-Al layered double hydroxide (LDH) nanoparticles demonstrate that MH nanocrystals possess higher flame-retardant efficiency and mechanical reinforcing effect by comparison with common micrometer grade MH particles. Kar and Bhowmick [65] have developed MgO nanoparticles and have investigated their effect as cure activator for halogenated mbber. The results as shown in Table 4.2 are promising. 

Under microwave heating, the Heck olefinations were achieved in 30-60 min, as opposed to 10-40 h by conventional heating. The recyclable heterogeneous LDH-Pd(0) catalytic system circumvents the need to use expensive and air-sensitive basic phosphines as ligands in the palladium-catalyzed coupling of chloroarenes. This novel Mg-Al layered double-hydroxide (LDH) support in the catalytic system stabilizes the nanopalladium particles and also supplies adequate electron density to the anchored palladium(O) species and facilitates the oxidative addition of the deactivated electron-rich chloroarenes. 

SYNTHESIS OF OSMATE EXCHANGED Mg-Al LAYERED DOUBLE HYDROXIDES (LDH-OSO4)... 

Kooli, F., Chisem, I. C., Vucelic, M. and Jones, W. (1996). Synthesis and properties of terephthalate and benzoate intercalates of Mg-Al layered double hydroxides possessing varying layer charge. Chem. Mater. 8, 1969. 

Kaneyoshi, M. and Jones, W. (1998). Exchange of interlayer terephthalate anions from a Mg-Al layered double hydroxide formation of intermediate interstratihed phases. Chem. Phys. Lett. 296, 183. 

Hydrogenations of acetonitrile and pentylnitrile (valeronitrile) in gas and liquid phases respectively were carried out on catalysts obtained from Ni/Mg/Al layered double hydroxides (LDHs) precursors of various Mg/Ni molar ratios. Their catalytic properties were compared with those of a commercial Ni/Al203 catalyst. Selectlvities to primary amines, higher than 90% were obtained on catalysts with Mg/Ni molar ratios in the range 0.3-1. This behaviour was correlated with the acido-basic properties of the solids characterized by TPD of NH3 and microcalorimetry of monoethylamine adsorption. Both studies show that upon Mg addition, the surface acidity, which is responsible for secondary amine formation decreases. 

Anionic copper(II)phthalocyanine monosulphonate (CuPcMs) and copper(II) phthalocyanine tetrasulphonate (CuPcTs) complexes have been successfully intercalated into the intergallery of Mg-Al layered double hydroxides through direct synthesis method. XRD results indicated an inclined orientation of the anion in the interlamellar space. A better thermal stability was noticed for the macrocycle ligand upon intercalation. The visible spectra showed a hyspochromic shift upon intercalation indicating disturbance of the macrocycle ligand pltmarity. An enhanced activity for the selective oxidation of cyclohexanol to cyclohexanone was observed for the intercalated complex in comparison with neat complex. 

Fig. 7.3. Mg-Al layered double hydroxide-supported palladium catalyst.

Costa, F. R., Abdel-Goad, M., Wagenknecht, U., and Heinrich, G., Nanocomposites based on polyethylene and Mg-Al layered double hydroxide I. Synthesis and characterization. Polymer, 46, 4447 453 (2005). 

Kuila, T, Acharya, H., Srivastava, S. K., and Bhowmick, A. K. 2007. Synthesis and characterization of ethylene vinyl acetate/Mg-Al layered double hydroxide nanocomposites. Journal of Applied Polymer Science 104 1845-1851. 

S. Cadars, G. Layrac, C. Gerardin, M. Deschamps, J.R. Yates, D. Tichit, D. Massiot, Identification and quantification of defects in the cation ordering in Mg/Al layered double hydroxides, Chem. Mater. 23 (2011) 2821—2831. 

Bin-Hussein, M. Z. Yahaya, A. H. Shamsul, M. SaUeh, H. M. Yap, T. Kiu, J. Acid fuchsin-inter-leaved Mg-Al-layered double hydroxide for the formation of an organic-inorganic hybrid nanocomposite. Mater. Lett. 2003, 58, 329-332. 

Kotal M, Kuila T, Srivastava SK, Bhowmick AK. Synthesis and characterization of polyurethane/Mg-Al layered double hydroxide nanocomposites. J Appl Polym Sci July 2009 114 2691-9. 

A tungstate-exchanged Mg-Al layered double hydroxide (LDH) was employed to catalyze oxidation of aliphatic tertiary amines to N-oxides by 30% aqueous H2O2 (Table 8.8) [117]. The reaction takes 1-3 h at room temperature. The use of dode-cylbenzenesulfonic acid sodium salt as an additive increased the rate of the oxidation by a factor of 2-3 except for N-methyl morpholine. An advantage with the LDH-W04 catalyst is that it can be reused. 

F. R. Costa, B. K. Satapathy, U. Wagenknecht, R. Weidisch, and G. Heinrich, Morphology and fracture behaviour of polyethylene/Mg-Al layered double hydroxide (LDH) nanocomposites. European Polymer Journal, 42 (2006), 2140-52. 

Costa FR, Wagenknecht U, Jehnichen D, Goad MA, Heinrich G (2006) Nanocranposiles based on polyethylene and Mg-Al layered double hydroxide. Part II. Rheological characterization more. Polymer 47 1649-1660... 

Nakayama, H., Wada, N., and Tsuhako, M. (2004) Intercalation of amino adds and peptides into Mg-Al layered double hydroxide by reconstruction method. Int. J. Pharm., 269, 469-478. 

D llario L., Fiancohni L, Martinelli A., Piozzi A. (2009), Insight into the Heparin-Toluidine Blue (C.I. Basic Blue l)late[3ctioif Dyes and Pigments, 80, 3, 343-8. Auxilio A.R., Andrews PC., Junk PC., Spiccia L. (2009), The Adsorption Behavior of Cl Acid Blue 9 onto Calcined Mg-Al Layered Double Hydroxides Dyes and Pigments, 81,2,103-12. 

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