A ray of hope for the environment is sustainable and green synthesis without the production of (toxic) waste. Solvent-free stoichiometric melting or kneading ball-milling reactions of aldehydes or ketones with carbonyl reagents yields arylhydrazones and oximes in quantitative yield. The carbonyl compounds can be quantitatively recovered from the imino derivatives by using gaseous NO(2).An effective methodology of kneading with a ball mill under temperature control was used for the stoichiometric quantitative preparation of synthetically versatile oximes and 2,4-dinitrophenylhydrazones from low-melting aldehydes and ketones. Also, a large number of phenylhydrazones are obtained by safe stoichiometric quantitative melt reactions. Advantages of this technique are short reaction times, eco-friendliness, and ease of handling under solvent-free conditions, as no waste-producing purifying workup is necessary. The different reactivities of aldehydes and ketones allow for easy separation of mixtures containing aldehydes and ketones. Furthermore, a new effective, gas-solid deprotection methodology for oximes was developed, using nitrogen dioxide as the reagent under solvent-free conditions to recover the aldehydes or ketones. The corresponding aldehydes were obtained free of overoxidized acids in quantitative yields.

Stoichiometric molecular solid‐state vibrational ball milling, solvent‐free kneading ball milling, and mechanochemical ball milling of varied aldehydes and ketones with unmodified sodium borohydride under temperature control uses all hydrogen atoms of the reducing agent in fast reactions. It provides quantitative yields of thermally stable sodium tetraalkoxyborates. The easily isolated solids are extremely sensitive towards hydrolysis, leading to quantitative yields of the corresponding alcohols. The rapid syntheses are regiospecific and stereoselective. Varied substituents are not attacked, including the bromine of α‐bromo ketones. Conjugated aldehydes and ketones provide quantitative yields of the allylic alcohols free of contamination by saturated alcohols that would occur by reaction in solution. Depending on the stoichiometric ratio, benzil is quantitatively reduced to benzoin (4:1 ratio) or dihydrobenzoin (2:1 ratio). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Nanoporous Cu 2 (BDC) 2 (BPY)-MOF was used as efficient and reusable heterogeneous catalyst to effect the aerobic cross-coupling of aromatic amines and phenyl boronic acid (Chan-Lam coupling). Ball-milling strategy was utilized for the first as a powerful green and energy-efficient method for the synthesis of this nanoporous metal-organic framework. Certain ratio of metal ion and organic linkers were held to improve the quality of nanostructures. Cu 2 (BDC) 2 (BPY) were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BrunauerEmmett-Teller (BET) surface area analysis.

Benzylic alcohols are quantitatively oxidized by gaseous nitrogen dioxide to give pure aromatic aldehydes. The reaction gas mixtures are transformed to nitric acid, which renders the processes free of waste. The exothermic gas-liquid or gas-solid reactions profit from the solubility of nitrogen dioxide in the neat benzylic alcohols. The acid formed impedes further oxidation of the benzaldehydes. The neat isolated benzaldehydes and nitrogen dioxide quantitatively give the benzoic acids. Solid long-chain primary alcohols are directly and quantitatively oxidized with nitrogen dioxide gas to give the fatty acids in the solid state. The oxidations with ubiquitous nitrogen dioxide are extended to solid heterocyclic thioamides, which gives disulfides, and to diphenylamine, which gives tetraphenylhydrazine. These sustainable (green) specific oxidation procedures produce no dangerous residues from the oxidizing agent or from auxiliaries.