Mechanochemistry: an overview

Abstract

The field of mechanochemistry is reviewed. A large number of mechanochemical reactions are described as well as industrial applications. CermetsMilling a soft metal with a hard ceramic material leads to the formation of valuable composites with new important properties: the cermets.On milling, the hard ceramic particles becomes imbedded in a metal host matrix. On further milling, the hard particles are micronized and the metal covers the fine ceramic units leading to spherical particles, the cermets [3,35]. Mechanical activation of mineralsMilling certain minerals alters their properties in ways that can be used in industry:1 Silica, alumina and alumino-silicates can be activated to be valuable catalyst, with the incorporation of small amount of metals [1,2].2 Bauxite can be activated by milling, allowing its extraction of Al(OH) 3 by concentrated NaOH solutions at lower temperatures. This allows a purer Al(OH) 3 to be obtained for Al production [1,2].3 Phosphate rock, the main source of P in the fertilizer industry, can be amorphized under high mechanical impact, leading to a material than can be attacked by the plant roots. This new fertilizer, tribophos, is cheaper than those obtained by treating the mineral with sulfuric or phosphoric acid [1,2].4 If instead of using sand and gravel in the concrete industry, the freshly ground rock is mixed with the cement and water, a very hard concrete results, superconcrete, with the cement phase strongly bound to the hard rock and sand phase [1,2].Many more uses of mechanical activation will certainly be developed in the future.

Mechanochemistry: opportunities for new and cleaner synthesis

“…[6a] According to Fernandez Bertran, [9] Walther Nernst (1864-1941, one of Ostwald"s students), also advocated this classification. An early solvent-free organic mechanochemical reaction, probably a cocrystallization, comes from 1893 by Ling and Baker, [10] and during the 1920s research was done into reactions of organic polymers such as cellulose.…”

“…[45] Mechanochemical methods offer solvent-free (or minimal solvent) routes to industrial materials and are therefore of great interest in devising more sustainable processes. [9,46] The potential to access materials not available by other methods is also of great interest. Figure 1a shows the growing number of patents filed per year that contain in the full description either of the terms "mechanochemistry" or "mechanochemical".…”

Pyrazoles as molecular probes to study the properties of co-crystals by solid state NMR spectroscopy

“…Actually, mechanical grinding produces chemical reactions (mecanochemistry [17][18][19][20][21][22]): this method as well as the co-solution method was also applied in Ref. 6 where the tautomerism of (1) was used as a tool to detect and to study the interaction with silica and alumina.…”

Ball Milling as a Tool Towards Solubility Problems in Synthesis – Simple and Solvent-free Preparation of K[B(CN)4]

“…Alternatively, according to the first law of thermodynamics, this energy amount may also be provided by mechanic action/work. [11][12][13] In practice, ball mills are approved tools for this: those commonly used are either of the vibratory or plantetary construction type. Mechanic activation by ball milling may be understood as an inverse Jahn-Teller effect, 13 with the excess energy delivered by pressure and shear forces being stored by the formation of non-equilibrium, non-stoichiometric defects, structural distortions and additional intergrain boundaries.…”