Photocatalytic Decarboxylation Amination Reaction Of Nano-Titanium Dioxide

Organic amines are widely applied in medicine,pesticides,materials and other d fine chemicals.They are one of the common chemical intermediates in organic synthesis.The reductive amination of carbonyl is one of the most classical and effective methods for the synthesis of amines.The reaction steps are generally followed by the condensation of amines with aldehydes to form imine intermediates,which are then reduced by hydrogenation.Similarly,the alkylation and amination of carbonyls are achieved by the addition of alkyl reagents and in situ generated imines.And,the alkyl radical generated by photocatalytic decarboxylation as alkyl reagent has been applied in many reactions.The reported addition reaction of alkyl radicals to imines induced by visible light has realized the construction of a series of multi-substituted amine compounds,which is an important expansion of the type of carbonyl alkylation amination reaction.However,the homogeneous metal complexes such as iridium and ruthenium used in these reactions are expensive and difficult to be separated and recycled,which limits their large-scale application to some extent.Compared with metal complexes or organic dye photocatalysts,inorganic semiconductor materials such as metal oxides,C₃N₄ and plasma photosensitizers are also widely used in the field of organic synthesis.Titanium dioxide is a kind of inorganic semiconductor materials widely used in metal oxides,which has wide band gap（3.2 eV）,low price,easy separation and stable thermal,optical and chemical properties.Therefore,exploring the synthesis and application of inorganic semiconductor photocatalyst on organic amine compounds is a problem worthy of study.This dissertation,we explored the three-component one-pot synthesis of amines by photo-promoted decarboxylation of nano-titanium dioxide,and successfully prepared a variety of secondary amines.This paper includes the following parts:（1）In this work,Photochemically promoted in situ decarboxylation of nano titanium dioxide to produce free radicals and multi-component reactions with aldehydes and amines were studied.This thesis scans titanium dioxide with different configurations and particle sizes,solvent,reaction equivalence ratio and other influencing factors,determines the optimal reaction conditions,and more than 30 secondary amine compounds were successfully prepared under the optimal conditions.（2）In this work,through free radical capture experiment and ternary ring opening experiment,we determined that the reaction experienced free radical process and speculated the possible mechanism of the reaction.Then,the microstructure of the catalysts before and after the reaction was characterized by TEM and BET.The results showed that there was no obvious change in the morphology of nano titanium dioxide before and after the reaction.