Wacker oxidation is an industry-adopted process to transform olefins into value-added epoxides and carbonyls.However,traditional Wacker oxidation involves the use of homogeneous palladium and copper catalysts for the ...Wacker oxidation is an industry-adopted process to transform olefins into value-added epoxides and carbonyls.However,traditional Wacker oxidation involves the use of homogeneous palladium and copper catalysts for the olefin addition and reductive elimination.Here,we demonstrated an ultrahigh loading Cu single atom catalyst(14%Cu,mass fraction)for the palladium-free Wacker oxidation of 4-vinylanisole into the corresponding ketone with N-methylhydroxylamine hydrochloride as an additive under mild conditions.Mechanistic studies by ^(18)O and deuterium isotope labelling revealed a hydrogen shift mechanism in this palladium-free process using N-methylhydroxylamine hydrochloride as the oxygen source.The reaction scope can be further extended to Kucherov oxidation.Our study paves the way to replace noble metal catalysts in the traditional homogeneous processes with single atom catalysts.展开更多
The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and s...The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.展开更多
1 Introduction A variety of Pd(Ⅱ)-catalyzed oxidative transformations ot allcenes with oxygen nucleophiles are catalyzed by PdX_(2)(X=OAc,Cl,etc)with CuX_(n)(n=1 or 2)under O_(2).In the so-called Wacker catalyst of s...1 Introduction A variety of Pd(Ⅱ)-catalyzed oxidative transformations ot allcenes with oxygen nucleophiles are catalyzed by PdX_(2)(X=OAc,Cl,etc)with CuX_(n)(n=1 or 2)under O_(2).In the so-called Wacker catalyst of such,Pd(OAc)_(2) is less reactive compared to PdCl_(2).In an attempt to increase the reactivity of Pd(OAc)_(2),we have now found that tuning of Cu site with catechol gives an intriguing reactivity to Pd(OAc)_(2),which is unprecedented in the chemistry of palladium.展开更多
基金National Research Foundation,Prime Minister’s Office,Singapore(No.NRF-CRP16-2015-02).
文摘Wacker oxidation is an industry-adopted process to transform olefins into value-added epoxides and carbonyls.However,traditional Wacker oxidation involves the use of homogeneous palladium and copper catalysts for the olefin addition and reductive elimination.Here,we demonstrated an ultrahigh loading Cu single atom catalyst(14%Cu,mass fraction)for the palladium-free Wacker oxidation of 4-vinylanisole into the corresponding ketone with N-methylhydroxylamine hydrochloride as an additive under mild conditions.Mechanistic studies by ^(18)O and deuterium isotope labelling revealed a hydrogen shift mechanism in this palladium-free process using N-methylhydroxylamine hydrochloride as the oxygen source.The reaction scope can be further extended to Kucherov oxidation.Our study paves the way to replace noble metal catalysts in the traditional homogeneous processes with single atom catalysts.
文摘The oxidation of styrene with molecular oxygen catalyzed by PdCl2+CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.
文摘1 Introduction A variety of Pd(Ⅱ)-catalyzed oxidative transformations ot allcenes with oxygen nucleophiles are catalyzed by PdX_(2)(X=OAc,Cl,etc)with CuX_(n)(n=1 or 2)under O_(2).In the so-called Wacker catalyst of such,Pd(OAc)_(2) is less reactive compared to PdCl_(2).In an attempt to increase the reactivity of Pd(OAc)_(2),we have now found that tuning of Cu site with catechol gives an intriguing reactivity to Pd(OAc)_(2),which is unprecedented in the chemistry of palladium.
