Investigation Into The Aerobic Oxidation Of Alcohol By Cu~?/TEMPO Catalytic System With Sole Ligand

The selective oxidation of alcohols to carbonyl compounds is an important transformation in synthetic organic chemistry.Their corresponding products,aldehydes or ketones,are important chemical precursors for the synthesis of medicines,vitamins and perfumes and play an important role in foundmental research and fine chemical productions.Thus,the development of practical and operational methods for aerobic oxidation to convert alcohols into aldehydes or ketones with high selectivity and efficiency becomes one of the hot research areas.This dissertation developed a kind of catalytic system for aerobic oxidation of alcohol basing on Cu^?/TEMPO with sole ligand and investigated its catalytic mechanism in details.The main content includes the following two aspects:The first part is mainly concerned with the homogeneous Cu^?/NMI/TEMPO catalyst system,which has been investigated for its catalysis on the aerobic oxidation of 1-octanol and other alcohols into aldehydes under room temperature.The catalytic species was found to be a Cu?I?centre coordinated by two NMI molecules and other two weakly bound solvent molecules,[Cu?NMI?₂?Sol?₂]^?10??Sol=solvent?.When CuI was used,this species could be[Cu?NMI?I?Sol?₂]?13?Not like being speculated previously,NMI in this system acts solely as a ligand and its role coordinated to the copper centre enhanced the electron density on the metal centre which promoted the O₂ binding in the catalysis.The labile solvent binding to the Cu?I?centre is essential to ensure both oxygen and substrate binding.The system possesses strong oxidizing capability in quantitative conversion of benzylic type of alcohols into aldehydes under room temperature by using air as the oxidant regardless of the substituents on the phenyl ring.The mechanism was discussed in detail using UV spectroscopy,high resolution mass spectrometry,X-ray single crystal diffraction,and electrochemical techniques.The aerobic oxidation of 1-octanol and other aliphatic alcohols was also nearly quantitative.A plausible mechanism was also proposed for the catalysis.The second part is mainly concerned with TMEDA?tetramethylethylenediamine?/CuI/TEMPO catalyst system,which catalyzes the aerobic oxidation of alcohol to corresponding aldehyde or ketone under mild conditions.By screening different bidentate ligands and reaction conditions,the optimal conditions for the reaction were obtained.The mechanism was discussed in detail via employing UV spectroscopy,high resolution mass spectrometry,X-ray single crystal diffraction and electrochemical techniques.Basing on the results of blank experiments and control experiments as well as capture of the crystal tructure of two main intermediates in the catalytic cycle,a possible catalytic mechanism is proposed.