Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and c...Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion.Here,we present a robust and weak-nucleophilicity nickel-iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis.Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH-compared with the weak-nucleophilicity Cl^(-),resultantly,the oxidation of OH-in electrolyte can be more easily achieved relative to chlorine ion oxidation,confirmed by ethylenediaminetetraacetic acid disodium probing test.Further,no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs.RHE,a potential that is far beyond the thermodynamic potential of chlorine ion oxidatio n.This concept and approach to reasonably designing weaknucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique.展开更多
Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecula...Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models.Herein,by taking the case study of nucleophilic addition reaction in aqueous solution,we extend the proposed multiscale reaction density functional theory(RxDFT)method to investigate the intrinsic free energy profile and total free energy profile,and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution.The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation.Meanwhile,the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase.In addition,we investigate the solvent effect on the reactions occurred near solid-liquid interfaces.It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10A distance to the substrate surface owing to the decrease of hydration free energy at the solid-liquid interface.展开更多
The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,...The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,and depression of the reaction rate by the addition of inhibitor.展开更多
A remarkable rate enhancement technique has been devised for a typical nucleophilic displacement reaction by using triphase catalytic materials based on tetraoctylammonium exchange forms of hectorite clay. Pseudo-firs...A remarkable rate enhancement technique has been devised for a typical nucleophilic displacement reaction by using triphase catalytic materials based on tetraoctylammonium exchange forms of hectorite clay. Pseudo-first order rate constants (kobs) for the conversion of 1-bromobutane to the corresponding chloride under triphase conditions using the clay catalyst in the presence of various polar cosolvents have been observed. The results here have shown that the addition of a cosolvent increases the catalytic activity of the triphase system by several fold. In addition, the results have demonstrated that each cosolvent has a unique concentration for achieving an optimum reaction rate.展开更多
As a versatile earth-abundant transition metal,Cu has long been widely applied in the C—C and C—X bond forming reactions.As for now,low-valent Cu(Ⅰ)is known to reduce the redox active electrophiles via an SET pathw...As a versatile earth-abundant transition metal,Cu has long been widely applied in the C—C and C—X bond forming reactions.As for now,low-valent Cu(Ⅰ)is known to reduce the redox active electrophiles via an SET pathway to give the corresponding radical and Cu(Ⅱ)species.The resulting Cu(Ⅱ)species can interact with the radical via the out-sphere pathway,affording the coupling product.Alternatively,Cu(Ⅱ)can trap the radical through the inner-sphere process to generate Cu(Ⅲ)species and then realize challenging bond formations due to the facile reductive elimination of Cu(Ⅲ)intermediate.Although copper catalysis has been widely applied in arylations of various nucleophiles,copper-catalyzed enantioconvergent nucleophilic substitutions of racemic alkyl electrophiles have been less explored,likely due to the difficulties in overcoming the reduction potential of alkyl electrophiles,elimination of side reactions,and enantiomeric control.In order to overcome the high reduction potential of alkyl electrophiles,the photo-induced strategy has been developed under mild conditions.An alternative strategy with new anionic tridentate ligands has also been reported in this regard.This review summarizes recent developments in copper-catalyzed enantioconvergent nucleophilic substitutions of alkyl electrophiles by various nucleophiles to realize C—N,C—C,C—B,C—P and C—O bond formations and their brief mechanistic studies.展开更多
The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of ar...The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.展开更多
The photostimulated reactions of benzyl chloride with carbazolyl nitrogen anion in dimethyl sulfoxide gave 9-benzylcarbazole and 3-benzylcarbazole.The reactions are suggested in term of S_(RN) I mechanism of nucleophi...The photostimulated reactions of benzyl chloride with carbazolyl nitrogen anion in dimethyl sulfoxide gave 9-benzylcarbazole and 3-benzylcarbazole.The reactions are suggested in term of S_(RN) I mechanism of nucleophilic substitution.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,No.22078052)the Fundamental Research Funds for the Central Universities(DUT22ZD207,DUT22LAB612)。
文摘Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion.Here,we present a robust and weak-nucleophilicity nickel-iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis.Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH-compared with the weak-nucleophilicity Cl^(-),resultantly,the oxidation of OH-in electrolyte can be more easily achieved relative to chlorine ion oxidation,confirmed by ethylenediaminetetraacetic acid disodium probing test.Further,no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs.RHE,a potential that is far beyond the thermodynamic potential of chlorine ion oxidatio n.This concept and approach to reasonably designing weaknucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique.
基金supported by National Natural Science Foundation of China(Nos.91934302,21878078 and 21808056)。
文摘Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models.Herein,by taking the case study of nucleophilic addition reaction in aqueous solution,we extend the proposed multiscale reaction density functional theory(RxDFT)method to investigate the intrinsic free energy profile and total free energy profile,and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution.The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation.Meanwhile,the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase.In addition,we investigate the solvent effect on the reactions occurred near solid-liquid interfaces.It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10A distance to the substrate surface owing to the decrease of hydration free energy at the solid-liquid interface.
文摘The anion of heterocyclic ketene aminals reacted with 2,4-dini- tro-halobenzenes to give an arylated product through the radical nucleo- philic substitution confirmed by ESR spectroscopy,ESR-spin trapping techni- que,and depression of the reaction rate by the addition of inhibitor.
文摘A remarkable rate enhancement technique has been devised for a typical nucleophilic displacement reaction by using triphase catalytic materials based on tetraoctylammonium exchange forms of hectorite clay. Pseudo-first order rate constants (kobs) for the conversion of 1-bromobutane to the corresponding chloride under triphase conditions using the clay catalyst in the presence of various polar cosolvents have been observed. The results here have shown that the addition of a cosolvent increases the catalytic activity of the triphase system by several fold. In addition, the results have demonstrated that each cosolvent has a unique concentration for achieving an optimum reaction rate.
基金the Key Research and Development Program of the Ministry of Science and Technology of China(2023YFA1508600)the start-up funding from Wuhan University.
文摘As a versatile earth-abundant transition metal,Cu has long been widely applied in the C—C and C—X bond forming reactions.As for now,low-valent Cu(Ⅰ)is known to reduce the redox active electrophiles via an SET pathway to give the corresponding radical and Cu(Ⅱ)species.The resulting Cu(Ⅱ)species can interact with the radical via the out-sphere pathway,affording the coupling product.Alternatively,Cu(Ⅱ)can trap the radical through the inner-sphere process to generate Cu(Ⅲ)species and then realize challenging bond formations due to the facile reductive elimination of Cu(Ⅲ)intermediate.Although copper catalysis has been widely applied in arylations of various nucleophiles,copper-catalyzed enantioconvergent nucleophilic substitutions of racemic alkyl electrophiles have been less explored,likely due to the difficulties in overcoming the reduction potential of alkyl electrophiles,elimination of side reactions,and enantiomeric control.In order to overcome the high reduction potential of alkyl electrophiles,the photo-induced strategy has been developed under mild conditions.An alternative strategy with new anionic tridentate ligands has also been reported in this regard.This review summarizes recent developments in copper-catalyzed enantioconvergent nucleophilic substitutions of alkyl electrophiles by various nucleophiles to realize C—N,C—C,C—B,C—P and C—O bond formations and their brief mechanistic studies.
文摘The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.
文摘The photostimulated reactions of benzyl chloride with carbazolyl nitrogen anion in dimethyl sulfoxide gave 9-benzylcarbazole and 3-benzylcarbazole.The reactions are suggested in term of S_(RN) I mechanism of nucleophilic substitution.
