913. Metal ions and complexes in organic reactions. Part V. Oxidations of primary and secondary amines with argentic picolinate

Abstract

Results are reported for oxidations of twenty-one primary or secondary alkyl-or arylalkyl-amines, a t 0-70", by a suspension of argentic picolinate in water or a polar organic solvent. Yields of aldehydes or ketones from most primary amines were 10-50%;in one case a cyanide was obtained. Yields of aldehydes or ketones from most secondary amines were 30-900/, ; in two cases the corresponding imines were obtained. By oxidation of unsymmetrical secondary amines of the type ArCH,*NHCR,, prepared from arylalkyl halides, the latter were efficiently converted into aldehydes, ArCHO. Argentic picolinate was superior to mercuric acetate or argentic oxide in cases examined, and some other transition-metal oxidants were ineffective. Mechanistic aspects of the oxidations are discussed.WE previously reported that various types of organic compound are oxidised by bivalent silver, employed in the form of argentic picolinate, and that some amines are particularly vulnerable to this reagent. We now describe preparations of aldehydes or ketones by this method from compounds which contain a primary or secondary amino-substituent on a saturated carbon atom ; the presence of an a-hydrogen atom is necessary. Imines are sometimes thus obtainable from secondary amines, and in other cases they are likely to be intermediates in the oxidations. Overall reactions may be formulated as in (1) and (2), for primary and secondary amines, respectively oc I +(1)

Sodium periodate/TEMPO as a selective and efficient system for amine oxidation

“…The oxidation of amines to get aldehydes is a particularly interesting transformation and despite its efficiency, the most common protocols suffer from the required use of stoichiometric amounts of toxic metal-containing reagents, such as KMnO 4 , 2 argentic picolinate, 3 ZnCr 2 O 7 , 4 and nicotinium dichromate, 5 or palladium-, 6 copper-, 7 and ruthenium-based 8 catalysts. In addition, these methodologies are sometimes affected by over oxidation of aldehydes to carboxylic acids.…”