Study On The Aerobic Oxidation Of Alcohols And Their Application

The oxidation reaction is an important part of organic chemistry,and it has been widely used in the petrochemical industry.In recent years,with the increasing consciousness of environment protection,the green catalytic oxidation technology has drawn more and more attention with air or oxygen as the terminal oxidant.Because molecular oxygen is abundant,environmental friendly and water is produced as the only benign by-product.Alcohols are important intermediate in organic synthesis,and can be widely found in fine chemical,pharmaceuticals intermediate and natural products.In addition,the oxidation products of alcohols such as aldehydes,ketones,carboxylic acids and esters are generally used as raw material in many organic synthesis reactions.With the development of green chemistry,it would be highly atomic economy and efficient method in organic synthesis using alcohols as start material instead of aldehydes,ketones,carboxylic acids with molecular oxygen as terminal oxidant.In this paper,using oxygen as the oxidant,we studied a series of oxidation reaction involving alcohol.A highly practical metal-free catalytic system has been developed for aerobic oxidation of secondary alcohols to corresponding ketones using 5 mol%of NHPI as catalyst and 10 mol%of TBN as co-catalyst with molecular oxygen serving as the terminal oxidant.A variety of aromatic,allylic,and heterocyclic alcohols were smoothly converted to desired products with moderate to excellent yields.This catalyst system can select oxidation primary alcohols to aldehydes,the peroxidation product was not obtained.Moreover,a possible radical mechanism was proposed.A practical and efficient catalyst system for the oxidation of alcohols to carbonyl compounds using catalytic amounts of DDQ and Fe(NO3)3 with air as the environmentally benign oxidant has been developed.A variety of benzylic,heterocyclic,allylic and propargylic alcohols were smoothly converted into aldehydes or ketones in good to excellent yields(78%-99%).Moreover,we explored the role of each catalyst and proposed a possible reaction mechanism.We developed a simple and highly efficient PdCl2(CH3CN)2/Bi(OTf)3-catalyzed system for the oxidative esterification of primary alcohols using molecule oxygen as benign oxidant under mild conditions.The catalyst system exhibited broad substrate scope and a variety of esters were obtained in yields of 43%-96%.It was highly efficient and atom economy using oxygen as the terminal oxidant and alcohol as raw material instead of traditional oxidant and aldehyde,carboxylic acids.The esterification reactions of primary alcohols such as aromatic alcohols,allylic alcohols,heterocyclic alcohols with methanol or other long-chain aliphatic alcohols proceed successfully without the addition of ligands.A mild and efficient methodology for the direct oxidative synthesis of nitriles from easily available alcohols and aqueous ammonia by employing CuCl/DABCO/4-HO-TEMPO as the catalysts was described.This protocol used the air as a green oxidant and aqueous ammonia as the nitrogen source at room temperature.A variety of aryl,heterocyclic and allylic alcohols were smoothly converted into the corresponding nitriles in good to excellent yields.A general,efficient,Iron nitrate/TEMPO-catalyzed protocol for aerobic oxidative synthesis of quinazolinones from easily accessible primary alcohols and 2-aminobenzamides with molecular oxygen as the terminal oxidant has been developed.We chose 10 mol%Fe(NI3)3,10 mol%TEMPO,0.5 equiv KOH in toluene at 100 ? under air as optimized reaction conditions,the desired products were obtained in 43%-96%yields.This practical reaction tolerated a broad scope of substrates.Notably,the aliphatic alcohols were also smoothly converted to the desired products.A plausible reaction mechanism has been proposed.In addition,the present synthetic protocol provided an efficient and concise strategy for the synthesis of quinazolinones.