The Studies On The Transition-Metal-Free And Selective Aerobic Alcohol Oxidation With Molecular Oxygen

The transformation from alcohols to the corresponding aldehydes orketones is one of the most important topics in organic chemistry. It is ofgreat importance to develop high-efficiency catalytic system. In the pastdecades, many research efforts have been directed at using molecularoxygen as the terminal oxidant. In this dissertation, twotransition-metal-flee catalytic aerobic oxidation systems were establishedwhich respectively use iso-amyl nitrite (IAMN) and tert-butyl nitrite(TBN) as the NO equivalents for the activation of molecular oxygen.In the TEMPO/HBr/IAMN catalytic system, benzylic alcoholsand heteroaromatic analogs was oxidized to their correspondingaldehydes and ketones with high conversions and selectivities using 2molï¼…of TEMPO as catalyst and 5 molï¼…of aqueous HBr and 5 molï¼…ofIAMN as co-catalysts in water. 2-Octanol could be also oxidized to 2-octanone in chloro-contained solvents, while 1-octanol was selectivelyoxidized into 1-octanal by tuning the ratio of 1,2-dichloroethane towater. Moreover, a plausible mechanism of formation of 1-octyl1-octanate, a usual by-product in the aerobic oxidation of 1-octanol, viathe hemi-acetal route was also proposed.iso-Amyl alcohol resulted from decomposition of IAMN probablyparticipated in the oxidation in some cases and complicated thepurification. On the contrary, the decomposed by-product of TBN istert-butyl alcohol, which can't be oxidized in most cases and dose notaffect most potential application. Thus we turn our attention to use TBNas the new NO source. The newly developed method was successfullyapplied in aerobic alcohol oxidation in a highly volume efficient andeconomy competitive process. Up to 16000 was achieved in thistransition-metal-free aerobic catalytic system. Under the optimal reactionconditions, various alcohol substrates were converted into theircorresponding carbonyl compounds with TEMPO/HBr/TBN as catalyst.A simple workup procedure can provide the pure oxidation products.Under the assistance of the minimum of solvent, the newly developedaerobic alcohol oxidation process is especially suitable for the solidalcohol substrates with high melting points.