Highly Efficient And Metal-free TEMPO-Based Catalytic Aerobic Oxdation Of Alcohols

Oxidation of alcohols to the corresponding carbonyl compounds is one of the most important fundamental reactions in organic synthesis. In this thesis, a TEMPO-based catalytic system for aerobic oxidation of alcohols was developed based on the previous studies of TEMPO catalytic aerobic oxidation of alcohols in our research group. This newly developed system was applied to the process development. The oxidation mechanism of this aerobic oxidation system was also discussed.Firstly, we developed a 4-BnO-TEMPO/TCCA/PEG-NO2 catalystic system, which is highly efficient, economical and environmentally friendly. In this system, aromatic alcohols can be oxidized to the corresponding aldehydes or ketones under the mild condition. It is noticeable that this catalytic system doesn't contain any metal and it is simple, easy to operate and a really metal free catalytic system for the aerobic oxidation of alcohols.Secondly, a more efficient 4-CH3O-TEMPO/HCl/PEG-NO2 catalytic system was developed. Compared with 4-BnO-TEMPO/TCCA/PEG-NO2 catalytic system, the blank test of the 4-CH3O-TEMPO/HCl/PEG-NO2 catalytic system is lower, and primary and secondary aliphatic alcohols can also be oxidized with high efficiency and selectivity. To our best knowledge, this catalytic system, whose conversion and selectivity of the oxidation reaction are high, and TON (turn-over number) can reach up to 56,000, is one of the most efficient TEMPO-based organic catalytic system so far.Thirdly, this new catalytic aerobic alcohol oxidation system was applied to the process development for preparation of benzaldehyde from benzyl chloride. The primary results showed that this process is cost-effective, environmentally friendly and simple operation. Furthermore, it is has the potential for the industrial application.Finally, the mechanism on the role of PEG in the 4-CH3O-TEMPO/HCl/PEG-NO2 and 4-BnO-TEMPO/TCCA/PEG-NO2 catalytic system was studied. PEG played a very important role in the oxidation systems both in promotion of oxidation efficiency and stabilization of TEMPO.