Studies On Selective Oxidation Of Alcohol Catalysed By Organo-catalytic System

The selective oxidation of alcohols to the corresponding aldehydes or ketones is a fundamental reaction in organic synthesis and plays a central role in industrial production. Rencently,the development of new catalytic oxidation systems with cheap and green oxidation reagents such as air,molecular oxygen and hydrogen peroxide is very attractive.Of particular interest are the use of molecular oxygen and air,which have several benefits,including low cost, improved safety,abundance,and water as the sole byproduct.In this paper,valuable explorations have been carried out on selective oxidation of alcohols to corresponding aldehydes and ketones using molecular oxygen(air) as primary oxidant.We develop TEMPO(2,2,6,6-tetramethylpiperidinyl-1-oxy) as a major catalyst, t-BuONO(tert-butyl nitrite)or HC1/t-BuONO as a cocatalyst for activation of oxygen to highly selective aerobic alcohol oxidation.Firstly we develops that TEMPO/t-BuONO can catalyze the selective,quantitative aerobic oxidation of alcohols by the oxidant-oxygen.With benzyl alcohol as a model substrate,the effect of different conditions(such as solvent,temperature,oxygen pressure and so on) on the reaction was studied.Benzyl alcohol can convert completely and the yield of benzaldehyde is up to 96%by using 1 tool%of TEMPO,1 mol%oft-BuONO,0.1 MPa of oxygen under 80℃for 1 h under optimum condition.Secondly,based on economy and energy efficiency,we develops that TEMPO/t-BuONO can catalyze the selective,aerobic oxidation of alcohols by the oxidant-air.Benzyl alcohol can convert completely and the yield ofbenzaldehyde is up to 96%by using 5 mol%of TEMPO,4 mol%of t-BuONO for 13 h at room temperature in air.At last,TEMPO/HCI/t-BuONO can catalyze the selective,quantitative aerobic oxidation of alcohols by the oxidant-air.Benzyl alcohol can convert completely and the yield of benzaldehyde is up to 97%by using 1 mol%of TEMPO,6 mol%of HC1 and 5 mol%of t-BuONO for 9 h at room temperature in air.The oxidation of abroad range of alcohols has been studied in the two organic catalytic systems above.The two organic catalytic systems can catalyse the selective and mild aerobic oxidation of abroad range of alcohols,which contain benzyl alcohol derivate,aliphatic primary and secondary alcohols,N heteroatom alcohol,to the corresponding aldehydes and ketones with high selectivity and yield,and the yield of alcohols is up to 93%-98%.