Ball-milling synthesis

WeiBe M, Zille M, Jacob K, Schmidt R, Stolle A. Hydroamination reactions of aUcynes with orf/zo-substituted anilines in ball mills synthesis of benzannulated N-heterocycles by a cascade reaction. Chem Eur J 2015 21 6511-22. 

By adhering to these conditions, Kaupp and coworkers performed a remarkable one-pot synthesis of highly substituted pyrroles [21]. When primary or secondary enamine esters 10-58 were ground with trans- 1,2-dibenzoylethene 10-59 in a ball-mill, the pyrroles 10-60 were obtained in quantitative yield (Scheme 10.15). In contrast, when in solution the yields were much lower and the reaction also required higher reaction temperatures. 

Nanoprocessing in Solid State in High-Energy Ball Mills 1.3.1 Processes for the Synthesis of Nanostructured Materials... 

A primary method of mechanochemical synthesis of nanostructured hydrides (nanohydrides) is processing by mechanical (ball) milling. Processes of manufacturing of nanocrystalline/nanostructured hydrides by ball milling are shown in Fig. 1.21. 

In the third method called mechanochemical activation synthesis (MCAS), a mixtnre of metal componnd, viz. metal chloride, is ball-milled to induce a reaction to yield a high-hydrogen capacity hydride. 

Much more efficient method of the synthesis of metal hydrides is a one-step method of reactive ball milling of elemental metal directly under hydrogen gas. The method of reactive mechanical alloying/milling of either elemental metals or preaUoyed... 

Other Methods of Synthesis of Nanostructured MgH than Ball Milling... 

From the Van t Hoff plot the decomposition enthalpy change AH) and entropy change (AS) for the first and second step were calculated to be AH j = 93.9 kJ/mol-Hj and AS, = 116.2 J/mol-H K, and AH = 102.2 kJ/mol-H and = 125.9 1/ mol-HjK. Taking into account the very high desorption temperature of this compound, much higher than that of a catalyzed MgH, and the fact that MgH is used in its synthesis by ball milling, the compound is not at all competitive to MgH. ... 

In essence, metal/intermetallic hydrides of AB, AB (Laves phases), AB, and A B have not been improved to any remarkable extent since the end of the 1990s. Nevertheless, there have been some efforts directed to either improvement of synthesis or properties of metal/intermetallic hydrides particularly by application of ball milling associated with nanostructuring. Some of these more recent efforts will be briefly discussed in the following sections. 

J. Huot, H. Enoki, E. Akiba, Synthesis, phase transformation, and hydrogen storage properties of ball-milled TiV(,Mnj J J. Alloys Compd. 453 (2008) 203-209. 

Three transition metal complex hydrides Mg NiH, Mg CoHj and Mg FeH have been extensively studied, especially from the standpoint of their synthesis to nanos-tructured hydrides by ball milling. 

Fichtner et al. [77, 78] added small Ti clusters (Tij3 6THF the synthesis of these clusters is described in [77]) to highly purified NaAlH by ball milling for 30 min and observed a substantial improvement of desorption/absorption kinetics for an alanate doped with 2 mol% of Ti clusters. A doped alanate desorbed on... 

An alternative indirect method of the synthesis of Mg(AlH )2 is the mechano-chemically activated metathesis reaction which was first reported by Dymova et al. [115, 116] according to the following reactions between MgH, AlH and AICI3 during ball milling... 

Fig. 3.42 XRD patterns of composites after the synthesis by ball milling for 20 h...

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