Kneading Ball-Milling and Stoichiometric Melts for the Quantitative Derivatization of Carbonyl Compounds with Gas-Solid Recovery

An effective methodology of kneading with a ball mill under temperature control was used for the stoichiometric quantiative preparation of synthetically versatile oximes and 2,4-dini-trophenylhydrazones from low-melting aldehydes and ketones. Also, a large number of phenylhydrazones are obtained by safe stoichiometric quantiative melt reactions. Advantages of this technique are short reaction times, eco-friendliness and ease of handling under solven-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.