Study On Oxidation Reactions Of Benzyl Alcohols And Alkylarmatics In Water

The oxidation of benzyl alcohols and alkylarmatics to carbonyl compounds is a fundamental reaction in organic synthesis.These corresponding aldehydes,ketones and acid are widely used in pesticide,organic industry,medicine industry,and so on.With the development of green chemistry requirements,mild,efficient,green systems for selective oxidation of benzyl alcohols and alkylarmatics still are the goal of pursuit.In this paper,we explored a series of catalytic systems to realize the green oxidations of benzyl alcohols and alkylarmatics in water.First,water-soluble 2N2O-Cu(II)complexes have been synthesized and used for the catalytic oxidation of benzylic alcohols to the corresponding aldehydes in pure water resulting in high yields of up to 94%.Importantly,the catalytic system exhibits a wide substrate scope,high functional group tolerance and can be reused directly for subsequent reaction cycles.Using this catalytic system,the product 4-methylbenzaldehyde could be produced on a multi-gram scale and in the complete absence of any organic solvent,surfactant,or phase transfer reagent.Second,we have developed a simple,efficient,and environmentally benign metal-free oxidative system of secondary alcohols in the presence of NBS/KOAc.The reaction was carried out in H2O/CH2Cl2(V:V=3:1,1.5 mL)at room temperature and the corresponding products were obtained in 46-98%.Importantly,the system has a wide substrate scope and a high tolerance for various functional groups.Moreover,this protocol can be applied to synthesize the benzophenone compound on a multi-gram scale.Third,we report a simple,yet efficient metal-free oxidation of secondary benzylic alcohols in the presence of t-butyl hydroperoxide(6 or 10 equiv.,70% TBHP)at 100 oC for 24 h with high yields of up to 98%.This type of reaction can be carried out using a wide variety of substrates,requires no other organic solvent and proves to be tolerant towards a variety of different functional groups.Last,we developed a simple and efficient Cu(II)-catalyzed ligand-free oxidation of diarylmethanes and secondary alcohols using 70% tert-butyl hydroperoxide(TBHP)in water.A series of diarylmethanes were directly oxidized into diaryl ketones in 67-98% yields.Additionally,various secondary alcohols were also transformed into the desired products in 48-98% yields.Importantly,the catalytic system in the absence of any organic solvent,surfactant,or phase transfer agent,had a wide substrate scope and a high tolerance for various functional groups.In conclusion,we have developed a series of methods for the oxidation of benzyl alcohols and alkylarmatics with high efficiency,mild conditions,a wide scope of substrates,eco-friendly,and well economic advantages,which could be applied in academic laboratories as well as on a multi-gram scale production.