Research On Inert C-H Bond Air Oxidative Transformation Reaction Promoted By Organic N-Oxyl Compounds

In the domain of modern petrochemical industry,oxidation is the most widely researched subject.A great quantity of olefin,methyl aromatic compounds and other industrial chemicals are produced by catalytic cracking and catalytic reforming of petroleum,which could produce high value-added chemical products by oxidation reaction.For example,alkenes can be converted into aldehydes by hydroformylation,and then aldehydes are oxidized into carboxylic acids which are widely used in human daily life.Methyl aromatic hydrocarbon compounds are selectively oxidized to aryl methanol,aryl formaldehyde and aryl formic acid by oxidation reaction.Nevertheless,the traditional oxidation methods of aldehydes have some disadvantages,such as high toxicity,high cost and serious environmental pollution.Up to now,a series of oxidation methods have been developed,but these methods also have some disadvantages,such as metal residues,the addition of expensive ligands and so on.Therefore,developing a green,clean and efficient method for the oxidation of aldehydes has long been a research subject for chemists.In modern chemical engineering manufacture,the C-C bond cleavage of nonpolar,strain-free and nonactivated alkyl aromatics are involved in catalytic reforming of oil and Hock rearrangement of cumene.Catalytic reforming of light gasoline fraction causes a serves overcapacity in toluene.And the toluene is mostly used for preparing benzene by dealkylation or xylene by toluene disproportionation.Therefore,it’s a very tricky problem for seeking after converting methyl aromatics represented by toluene into high value-added industrial products.Our research group has been devoted to the study of free radical oxidation promoted by organic N-oxyl compounds.At present,we have developed highly selective and deeply controllable oxidation methods for ammoxidation and oxidation of aromatic alkanes into nitriles and ketones.Based on our laboratory research of clean oxidation reaction for industrialization and oxidation strategy of C-H bond promoted by organic N-oxyl compounds,we have carried out three parts of research work in this thesis:1.Enlightened by the approach and methodology of preparing phenol and acetone through rearrangement of cumene,methyl aromatics are converted into aryl boronates by using a tandem demethylated radical borylation strategy with the help of N-hydroxyphthalimide,tert-butyl nitrite and tert-butyl isonicotinate have been developed.Mechanistic analysis suggests that N-hydroxyphthamide esters are involved in the borylation reaction.The results show that toluene and xylene are suited for the borylation reaction.And this method provides a new straightforward approach for the derivatization of toluene and xylene into high value-added aryl boronates.2.Based on the research of aerobic oxidation reaction by our group,aldehydes are cleanly oxidized to carboxylic acids under mild conditions by using NHPI as catalyst and oxygen as oxidant.We found that a wide range of aldehydes bearing diverse functional groups could be converted into carboxylic acids in high yields.And the aerobic oxidation of aldehydes to carboxylic acids could be realized in both acetonitrile and water under mild conditions.3.During exploring the above two parts of work,N-hydroxyphthamide esters were detected in the mechanistic analysis.And the N-hydroxyphthamide esters are widely used in photocatalytic organic reactions.Therefore,we have developed an oxidative esterification method for the preparation of N-hydroxyphthamide esters using aldehydes and methyl aromatics as starting materials.And it provides a straightforward approach for the synthesis of the N-hydroxyphthamide esters.