Targeted Activation Of Ethanol Chemical Bond And Directional Construction Of C-C Bond

Ethanol could be produced from abundant sources and is an important platform molecule for synthesizing high-value chemicals.However,ethanol is rich in chemical bonds and considerably stable,leading to the bonds interfere with each other.So,the targeted activation of the specific bond is difficult.To address this challenge,based on the idea of multi-site cooperative catalysis,multi-site catalytic structure of the supported metal catalysts for the targeted activation of ethanol and the directional construction of C-C bond has been designed and constructed in this dissertation.The specific research contents and results are as follows:（1）Aiming at the challenges faced by ethanol dehydrogenative coupling to C₄₊alcohols:ethanol direct dehydrogenation is difficult to be generated and the multi-step tandem reactions restrict each other,each step has a competitive pathway.The research idea of metal-base and metal-acid-base synergistic catalysis has been proposed.In this viewpoint,the layered double oxide（LDO）supported atomic Ru（Ru/Mg Al-LDO）with acid-base bi-function and the tailored density of acid-base sites has been employed.Atomic Ru synergetic with surface base sites on LDO for promoting ethanolα-C-H/O-H bonds dehydrogenation to acetaldehyde,and then atomic Ru acts as the additional Lewis acid site synergistic with acid-base sites on LDO for acetaldehyde condensation.As a result,30%of the ethanol conversion and 83%of the C₄₊alcohols selectivity have been achieved.（2）Aiming at the challenges faced by ethanol cross dehydrogenative coupling to hydroxyethyl N-heterocycles:it is difficult to targeted activation of ethanolα-C-H bond to efficiently generate hydroxyethyl radical（·CH（OH）CH₃）and the stabilization of generated·CH（OH）CH₃ radical.In this viewpoint,the catalytic strategy of H-bonding protection of ethanol O-H bond has been proposed,and graphitic carbon nitride supported atomic Fe（Fe@GCN）has thus been proposed.The precise modulation on the atomic Fe-N coordination in the cavity from three heptazines have been elaborated:Fe（II）-N₄-heptazine assisted with the uncoordinated N from the free one heptazine has presented a synergistic H bonding protection of ethanol O-H bond.As a result,a targeted generation and an excellent stabilization of hydroxyethyl radical can be achieved mediated by free radical initiators.The catalytic strategy has been tolerated by varied substrates and can be applied to the hydroxyalkylation of various N-heterocycles with C₂-C₅ aliphatic alcohols,achieving a yield of 49-98%.（3）The hydroxyalkylation of alcohols to construct chiral carbon atoms is of more important significance.On the basis of the H-bonding O-H bond protection strategy,the catalytic strategy of multiple hydrogen bonds synergistic with chiral phosphoric acid for the asymmetric hydroxyethylation of N-heterocycles,to prepare chiral hydroxyethyl N-heterocycles with high stereoselectivity has been proposed.As a result,95%of the benzimidazole conversion,86%of the 2-（1-hydroxyethyl）benzimidazole selectivity,and 84%of the ee value have been achieved.Moreover,the matching mechanism between the multiple hydrogen bonds and the chiral induction environment has been investigated.