Herein,we developed the first example of copper-catalyzed silicon radical-initiated 1,4-silylcyanation of unactivated 1,3-enynes,which provided an efficient method to access CN-bearing tri-and tetrasubstituted homoall...Herein,we developed the first example of copper-catalyzed silicon radical-initiated 1,4-silylcyanation of unactivated 1,3-enynes,which provided an efficient method to access CN-bearing tri-and tetrasubstituted homoallenylsilane derivatives in high yields with excellent regioselectivities.This protocol featured good functional group compatibility and broad substrate scopes,enabling the formation of C-Si bond under cheap copper catalyst with a low loading.Furthermore,this means showed potential application value in the late-stage functionalization of natural products.展开更多
Photocatalytic and photoinduced silyl radicals cascade cyclization procedures for the green and simple preparation of fused tetracyclic skeleton silylated indolo[2,1-a]isoquinoline-6(5H)-ones from 2-aryl-N-acryloyl in...Photocatalytic and photoinduced silyl radicals cascade cyclization procedures for the green and simple preparation of fused tetracyclic skeleton silylated indolo[2,1-a]isoquinoline-6(5H)-ones from 2-aryl-N-acryloyl indoles with hydrosilanes are developed.The photocatalytic reaction is carried out with 9,10-dicyanoanthracene(DCA)as an organophotocatalyst and 3-acetoxyquinuclidine as hydrogen atom transfer(HAT)catalyst at room temperature under metal-and oxidant-free conditions.The keys to the success of photoredox-catalytic conversion include(1)the reductive quenching of DCA^(*)[E_(1/2)(*P/P^(-))=+1.97 V vs.SCE in MeCN]by 3-acetoxyquinuclidine(E_(p)=+1.22 V vs.SCE in MeCN),and(2)the thermodynamic feasibility of hydrogen atom abstraction from hydridic Si-H bond by electrophilic N^(+·).Particularly,the simple photoinduced cascade cyclization using(TMS)3SiH with 2-aryl-N-acryloyl indoles was exploited via an electron-donor-acceptor(EDA)complex under visible light irradiation.展开更多
A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindol...A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindoles,and cishydroindenes bearing silyl enol ether in good to excellent yields and excellent stereoselectivities.Additionally,the versatility of this method was demonstrated through a gram-scale experiment and various downstream transformations,highlighting its utility.展开更多
N-Trimethylsilylvaline trimethylsilyl ester IIa, N-triethylsilylvaline triethylsilyl ester IIb and N-tert-butyldimethylsilylvaline tert-butyldimethylester IIc showed evidently different reactivities with O,O'-phen...N-Trimethylsilylvaline trimethylsilyl ester IIa, N-triethylsilylvaline triethylsilyl ester IIb and N-tert-butyldimethylsilylvaline tert-butyldimethylester IIc showed evidently different reactivities with O,O'-phenylenephosphorylchloride The formation speed of the fmal spiro-bicyclic pentacoordinated phosphorus compounds IV depends on the intramolecular transfer ability of the silyl moiety crucially展开更多
1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of pr...1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of preparing fused heterocyclic compounds was offered by 1,3-dipolar cycloaddition reaction of silyl nitronates to 1.展开更多
Trimethylsilylation of alcohols was achieved using 1,1,1,3,3,3-hexamethyldisilazane（HMDS） as silylating agent,in the presence of polyvinylpolypyrrolidonium tribromide in acetonitrile at room temperature.Also a varie...Trimethylsilylation of alcohols was achieved using 1,1,1,3,3,3-hexamethyldisilazane（HMDS） as silylating agent,in the presence of polyvinylpolypyrrolidonium tribromide in acetonitrile at room temperature.Also a variety of alcohols were converted into alkyl formates by ethyl formate and a catalytic amount of polyvinylpolypyrrolidonium tribromide under solvent free conditions at room temperature.展开更多
Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical proper...Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the surface of the graphite anode. Therefore, Si-additives modified by Si–O functional groups can be effectively used to increase the overall electrochemical performance of the LMO cathode material.展开更多
The chemistry of silylene-transition-metal complexes LnM(=SiR2)SiR3 is one of the attractive synthetic targets in organometallic chemistry for such complexes are key intermediates in many transition metal-catalyzed sy...The chemistry of silylene-transition-metal complexes LnM(=SiR2)SiR3 is one of the attractive synthetic targets in organometallic chemistry for such complexes are key intermediates in many transition metal-catalyzed systems.In the present work,the novel insertion reactions of an isocyanide into the Cp*Mo(CO)2(=SiMe2)(SiMe3)Si-C bond were investigated extensively by using the DFT method.The effective core potentials(ECP)with a double-ζvalence basis set(LanL2DZ)were employed for Mo and Si and the standard 6-31G basis set for all other atoms.Polarization functions[22]were added for Si(ζd=0.262),C(ζd=0.8)and N(ζd=0.8).The effect of solvent was evaluated with the standard PCM model.Our calculations show that the two-step channel is energetically favorable,and the solvation mode has minor influence on the relative energies.展开更多
Silylated Ti-grafted hexagonal mesoporous silica （HMS） catalyst was prepared by the chemical vapor deposition （CVD） using TIC14 as titanium source and hexamethyldisilazane （HMDSZ） as silylating agent. The sample...Silylated Ti-grafted hexagonal mesoporous silica （HMS） catalyst was prepared by the chemical vapor deposition （CVD） using TIC14 as titanium source and hexamethyldisilazane （HMDSZ） as silylating agent. The samples were characterized by XRD, N2- adsorption, PTIR, 29Si NMR, DR UV-vis, and evaluated by epoxidation of styrene, propylene, cyclohexene, and 1-hexene with cumene hydroperoxide （CLIP） as oxidant, respectively. It is revealed that the catalyst possesses typical mesoporous structure, high hydrophobicity and highly dispersed tetracoordinated titanium sites and hence exhibits excellent performance in epoxidation of olefins.展开更多
An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achiev...An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.展开更多
Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means...Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.展开更多
The development of efficient method to prepare poly(silyl ether)s(PSEs)is highly desirable.Herein,an environmentally sustainable copper-catalyzed dehydrocoupling polymerization was developed with good yields and high ...The development of efficient method to prepare poly(silyl ether)s(PSEs)is highly desirable.Herein,an environmentally sustainable copper-catalyzed dehydrocoupling polymerization was developed with good yields and high molecular weight(up to 48,400 of Mn and up to 97%yield).Monomers of different types(AB type or AA and BB type)are suitable to afford PSEs.The PSEs show good thermal stability and low glass-transition temperature.展开更多
A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourie...A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.展开更多
Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This ...Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This unique regioselectivity is distinctly different with other Lewis acidic promoters and may be attributed to the high oxyphilicity of IMg+.展开更多
An iron-catalyzed coupling reaction of difluoroenol silyl ethers and cyclobutanone oxime esters is described. This protocol provides a convenient access to various previously unknown and potentially useful gem-difluor...An iron-catalyzed coupling reaction of difluoroenol silyl ethers and cyclobutanone oxime esters is described. This protocol provides a convenient access to various previously unknown and potentially useful gem-difluoromethylenated ketonitriles inmoderate to good yields. The transformations of resulting products to other fluorinecontaining products is also documented.展开更多
A silylated PNP ligand with asymmetric structure was synthesized using(γ-aminopropyl)triethoxysilane and chlorodiphenyl phosphine as raw materials.The optimal synthetic conditions of the PNP ligand were obtained by c...A silylated PNP ligand with asymmetric structure was synthesized using(γ-aminopropyl)triethoxysilane and chlorodiphenyl phosphine as raw materials.The optimal synthetic conditions of the PNP ligand were obtained by conditional experiments and were as follows:dichloromethane was solvent,triethylamine was acid acceptor,the mole ratio of chlorodiphenylphosphine and(γ-aminopropyl)triethoxysilane was 2.1∶1,the dropping temperature of chlorodiphenylphosphine was-5℃,the dropping time was 30 min,the reaction temperature was 25℃and the reaction time was 12 h.Under the conditions,the yield of the silylated PNP ligand was 91.20%.Based on grey correlation analysis,the dropping temperature was the main factor for the yield of the silylated PNP ligand.The single-active central chromium catalyst based on the silylated PNP ligand was synthesized by complexation reaction with the silylated PNP ligand and chromium chloride tetrahydrofuran complex as materials,and the yield was 95.25%.The chemical structures of the silylated PNP ligand and the corresponding chromium catalyst were confirmed by elemental analysis,FT-IR,^(1)H NMR,MS and ICP.The single-active central chromium catalyst based on the silylated PNP ligand had good catalytic activity for ethylene oligomerization,and the content of C_(8)olefin was 72.40%,which was superior to Si-Schiff-Cr based on intermolecular coordination.展开更多
A new chiral tetrathiafulvalene （TTF） derivative and related silyl-substituted 1,3-dithiole-2-（thi）one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure o...A new chiral tetrathiafulvalene （TTF） derivative and related silyl-substituted 1,3-dithiole-2-（thi）one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure of the silyl-substituted 1,3-dithiole-2-one revealed the high degree of conjugation of the five- membered ring moiety in the compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry and the results indicated that the electron-donating ability of the chiral TI＂F derivative was similar to that of BEDT-TTF. The AE value for the new TTF derivative was smaller than those for TTF and BEDT-TrF, indicative of decreased Coulombic repulsion in the dicationic redox state. Formation of charge-transfer （CT） complex between the new donor and electron acceptor 2,3-dichloro-5,6-dicvano-1,4-benzocluinone （DDO） was demonstrated.展开更多
Cross-linking of silyl-modified polymers occurs at the alkoxysilane groups attached to the ends of polymer chains by hydrolysis and polycondensation mechanisms in the presence of moisture. During these reactions, thre...Cross-linking of silyl-modified polymers occurs at the alkoxysilane groups attached to the ends of polymer chains by hydrolysis and polycondensation mechanisms in the presence of moisture. During these reactions, three different physical states can be identified (viscous, skin effect and cross-linked state). Knowledge of the evolution of these states at each reaction time is essential to determine the open time for the adhe-sive industry and is generally obtained by a manual method. Automation of this moni-toring could avoid operator error and could be used for very long cross linking reac-tions or to screen a large number of catalysts. Thus, a contactless micro process tech-nology was developed to correlate these physical states with an optical technology, Raman spectroscopy, by monitoring the decrease in intensity of the Si-OCH<sub>3</sub> groups during chemical reactions. This online characterization method can also be used to compare the efficiencies of several catalysts for the cross-linking of silyl-modified polymers, using a minimum amount of chemical materials.展开更多
Effects of silylation on surface properties and catalytic performance of Zn-IM5 for butane aromatization were studied in this paper. Collidine-IR and NH3-TPD analyses revealed that the silylation treatment not only de...Effects of silylation on surface properties and catalytic performance of Zn-IM5 for butane aromatization were studied in this paper. Collidine-IR and NH3-TPD analyses revealed that the silylation treatment not only decreased the quantity of both strong and weak acid sites but also led to a slightly reduced intensity of weak acidity. Silylation of the catalyst promoted the selectivity of BTX by narrowing the channel and cutting the acidity. The effect of temperature of silylation and amount of Si loading were evaluated. The best condition has specified a temperature of 50 ℃ and a SiO_2 loading of 4.0%.展开更多
基金support of this work by the funding of the National Natural Science Foundation of China(No.22371269)the State Key Laboratory of Elementoorganic Chemistry Nankai University(No.202001)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0450301)the Open Project of Key Laboratory of Organosilicon Chemistry,and Material Technology of Ministry of Education,Hangzhou Normal University(No.KFJJ2022013)。
文摘Herein,we developed the first example of copper-catalyzed silicon radical-initiated 1,4-silylcyanation of unactivated 1,3-enynes,which provided an efficient method to access CN-bearing tri-and tetrasubstituted homoallenylsilane derivatives in high yields with excellent regioselectivities.This protocol featured good functional group compatibility and broad substrate scopes,enabling the formation of C-Si bond under cheap copper catalyst with a low loading.Furthermore,this means showed potential application value in the late-stage functionalization of natural products.
基金the Tianshan Talents Program for Leading Talents in Science and Technology Innovation(No.2022TSYCLJ0016)the National Natural Science Foundation of China(Nos.21961037 and 22201241)+3 种基金the Program for Tianshan Innovative Research Team of Xinjiang Uygur Autonomous Region(No.2021D14011)the Graduate Innovation Project of Xinjiang Uygur Autonomous Region(No.XJ2021G036)the Key Program of Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01D06)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Nos.2021D01E10 and 2022E01042).
文摘Photocatalytic and photoinduced silyl radicals cascade cyclization procedures for the green and simple preparation of fused tetracyclic skeleton silylated indolo[2,1-a]isoquinoline-6(5H)-ones from 2-aryl-N-acryloyl indoles with hydrosilanes are developed.The photocatalytic reaction is carried out with 9,10-dicyanoanthracene(DCA)as an organophotocatalyst and 3-acetoxyquinuclidine as hydrogen atom transfer(HAT)catalyst at room temperature under metal-and oxidant-free conditions.The keys to the success of photoredox-catalytic conversion include(1)the reductive quenching of DCA^(*)[E_(1/2)(*P/P^(-))=+1.97 V vs.SCE in MeCN]by 3-acetoxyquinuclidine(E_(p)=+1.22 V vs.SCE in MeCN),and(2)the thermodynamic feasibility of hydrogen atom abstraction from hydridic Si-H bond by electrophilic N^(+·).Particularly,the simple photoinduced cascade cyclization using(TMS)3SiH with 2-aryl-N-acryloyl indoles was exploited via an electron-donor-acceptor(EDA)complex under visible light irradiation.
基金financial support from the National Key R&D Program of China(No.2022YFF1202600)the National Natural Science Foundation of China(Nos.22001172,22071155,and22371188)+4 种基金the Science and Technology Commission of Shanghai Municipality(Nos.20XD1403600 and 20400750300)the Shanghai Municipal Education Commission(No.2019-01-07-00-10-E00072)the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(No.ZYYCXTD-202004)the Shanghai Municipal Health Commission/Shanghai Municipal Administration of Traditional Chinese Medicine[No.ZY(2021-2023)-0501]Organizational Key R&D Program of SHUTCM(No.2023YZZ01)。
文摘A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindoles,and cishydroindenes bearing silyl enol ether in good to excellent yields and excellent stereoselectivities.Additionally,the versatility of this method was demonstrated through a gram-scale experiment and various downstream transformations,highlighting its utility.
文摘N-Trimethylsilylvaline trimethylsilyl ester IIa, N-triethylsilylvaline triethylsilyl ester IIb and N-tert-butyldimethylsilylvaline tert-butyldimethylester IIc showed evidently different reactivities with O,O'-phenylenephosphorylchloride The formation speed of the fmal spiro-bicyclic pentacoordinated phosphorus compounds IV depends on the intramolecular transfer ability of the silyl moiety crucially
基金This work was supported by the NNSFC (No.29672004).
文摘1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of preparing fused heterocyclic compounds was offered by 1,3-dipolar cycloaddition reaction of silyl nitronates to 1.
文摘Trimethylsilylation of alcohols was achieved using 1,1,1,3,3,3-hexamethyldisilazane（HMDS） as silylating agent,in the presence of polyvinylpolypyrrolidonium tribromide in acetonitrile at room temperature.Also a variety of alcohols were converted into alkyl formates by ethyl formate and a catalytic amount of polyvinylpolypyrrolidonium tribromide under solvent free conditions at room temperature.
基金supported by National Research Foundation of Korea grant from the Korean government (MSIP) (NRF2019R1C1C1002249, and NRF-2017M1A2A2044506)。
文摘Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the surface of the graphite anode. Therefore, Si-additives modified by Si–O functional groups can be effectively used to increase the overall electrochemical performance of the LMO cathode material.
基金supported by the National Natural Science Foundation of China(No.11174215)
文摘The chemistry of silylene-transition-metal complexes LnM(=SiR2)SiR3 is one of the attractive synthetic targets in organometallic chemistry for such complexes are key intermediates in many transition metal-catalyzed systems.In the present work,the novel insertion reactions of an isocyanide into the Cp*Mo(CO)2(=SiMe2)(SiMe3)Si-C bond were investigated extensively by using the DFT method.The effective core potentials(ECP)with a double-ζvalence basis set(LanL2DZ)were employed for Mo and Si and the standard 6-31G basis set for all other atoms.Polarization functions[22]were added for Si(ζd=0.262),C(ζd=0.8)and N(ζd=0.8).The effect of solvent was evaluated with the standard PCM model.Our calculations show that the two-step channel is energetically favorable,and the solvation mode has minor influence on the relative energies.
文摘Silylated Ti-grafted hexagonal mesoporous silica （HMS） catalyst was prepared by the chemical vapor deposition （CVD） using TIC14 as titanium source and hexamethyldisilazane （HMDSZ） as silylating agent. The samples were characterized by XRD, N2- adsorption, PTIR, 29Si NMR, DR UV-vis, and evaluated by epoxidation of styrene, propylene, cyclohexene, and 1-hexene with cumene hydroperoxide （CLIP） as oxidant, respectively. It is revealed that the catalyst possesses typical mesoporous structure, high hydrophobicity and highly dispersed tetracoordinated titanium sites and hence exhibits excellent performance in epoxidation of olefins.
基金Financial support from the National Natural Science Foundation of China(Nos.21372144,81473085)Department of Science and Technology of Shandong Province
文摘An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.
文摘Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.
基金support from National Natural Science Foundation of China(No.21690074)Chinese Academy of Sciences(Nos.XDB17020300,DICP I202015)is acknowledged.
文摘The development of efficient method to prepare poly(silyl ether)s(PSEs)is highly desirable.Herein,an environmentally sustainable copper-catalyzed dehydrocoupling polymerization was developed with good yields and high molecular weight(up to 48,400 of Mn and up to 97%yield).Monomers of different types(AB type or AA and BB type)are suitable to afford PSEs.The PSEs show good thermal stability and low glass-transition temperature.
基金funded by Qingyang Science and Technology Support Project(KT2019-03)。
文摘A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.
基金We are grateful for the financial supports from the National Outstanding Youth Fund No.29925204)the Foundation for University Key Teacher by the Ministry of Education of Chinaa Visiting Fund of the National Laboratory of Applied Organic Chemistry.
文摘Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This unique regioselectivity is distinctly different with other Lewis acidic promoters and may be attributed to the high oxyphilicity of IMg+.
基金National Natural Science Foundation of China (Nos.21421002,21991211)the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB20000000)。
文摘An iron-catalyzed coupling reaction of difluoroenol silyl ethers and cyclobutanone oxime esters is described. This protocol provides a convenient access to various previously unknown and potentially useful gem-difluoromethylenated ketonitriles inmoderate to good yields. The transformations of resulting products to other fluorinecontaining products is also documented.
基金supported by Key Research and Development Project of Heilongjiang Province(JD22A026)
文摘A silylated PNP ligand with asymmetric structure was synthesized using(γ-aminopropyl)triethoxysilane and chlorodiphenyl phosphine as raw materials.The optimal synthetic conditions of the PNP ligand were obtained by conditional experiments and were as follows:dichloromethane was solvent,triethylamine was acid acceptor,the mole ratio of chlorodiphenylphosphine and(γ-aminopropyl)triethoxysilane was 2.1∶1,the dropping temperature of chlorodiphenylphosphine was-5℃,the dropping time was 30 min,the reaction temperature was 25℃and the reaction time was 12 h.Under the conditions,the yield of the silylated PNP ligand was 91.20%.Based on grey correlation analysis,the dropping temperature was the main factor for the yield of the silylated PNP ligand.The single-active central chromium catalyst based on the silylated PNP ligand was synthesized by complexation reaction with the silylated PNP ligand and chromium chloride tetrahydrofuran complex as materials,and the yield was 95.25%.The chemical structures of the silylated PNP ligand and the corresponding chromium catalyst were confirmed by elemental analysis,FT-IR,^(1)H NMR,MS and ICP.The single-active central chromium catalyst based on the silylated PNP ligand had good catalytic activity for ethylene oligomerization,and the content of C_(8)olefin was 72.40%,which was superior to Si-Schiff-Cr based on intermolecular coordination.
基金the support by"the Fundamental Research Funds for the Central Universities"
文摘A new chiral tetrathiafulvalene （TTF） derivative and related silyl-substituted 1,3-dithiole-2-（thi）one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure of the silyl-substituted 1,3-dithiole-2-one revealed the high degree of conjugation of the five- membered ring moiety in the compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry and the results indicated that the electron-donating ability of the chiral TI＂F derivative was similar to that of BEDT-TTF. The AE value for the new TTF derivative was smaller than those for TTF and BEDT-TrF, indicative of decreased Coulombic repulsion in the dicationic redox state. Formation of charge-transfer （CT） complex between the new donor and electron acceptor 2,3-dichloro-5,6-dicvano-1,4-benzocluinone （DDO） was demonstrated.
文摘Cross-linking of silyl-modified polymers occurs at the alkoxysilane groups attached to the ends of polymer chains by hydrolysis and polycondensation mechanisms in the presence of moisture. During these reactions, three different physical states can be identified (viscous, skin effect and cross-linked state). Knowledge of the evolution of these states at each reaction time is essential to determine the open time for the adhe-sive industry and is generally obtained by a manual method. Automation of this moni-toring could avoid operator error and could be used for very long cross linking reac-tions or to screen a large number of catalysts. Thus, a contactless micro process tech-nology was developed to correlate these physical states with an optical technology, Raman spectroscopy, by monitoring the decrease in intensity of the Si-OCH<sub>3</sub> groups during chemical reactions. This online characterization method can also be used to compare the efficiencies of several catalysts for the cross-linking of silyl-modified polymers, using a minimum amount of chemical materials.
基金financially supported by the Opening Project of the State Key Laboratory of Catalytic Material and Reaction Engineering of Sinopec Research Institute of Petroleum Processing. (No. 33600000-14-ZC0607-0010)
文摘Effects of silylation on surface properties and catalytic performance of Zn-IM5 for butane aromatization were studied in this paper. Collidine-IR and NH3-TPD analyses revealed that the silylation treatment not only decreased the quantity of both strong and weak acid sites but also led to a slightly reduced intensity of weak acidity. Silylation of the catalyst promoted the selectivity of BTX by narrowing the channel and cutting the acidity. The effect of temperature of silylation and amount of Si loading were evaluated. The best condition has specified a temperature of 50 ℃ and a SiO_2 loading of 4.0%.
