The ketalization of glycerol with acetone was conducted over an ionic liquid[P(C4H9)3C14H29][TsO](TTPT)in a batch reactor.A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a ...The ketalization of glycerol with acetone was conducted over an ionic liquid[P(C4H9)3C14H29][TsO](TTPT)in a batch reactor.A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a maximum solketal yield of 86%is achieved at acetone/glycerol molar ratio of 6/1,reaction time of 0.5 h,reaction temperature of 303 K,catalyst amount of 5 wt%of glycerol.TTPT was recycled and reused for ten times without obvious losses in terms of quantity and activity.Furthermore,effects of various experimental parameters(stirring speed,catalyst loadings,temperature and reactant composition)on the reaction kinetics are investigated.In terms of kinetics modeling,Kγis fitted by reactant composition at the temperature range 298 K–323 K,which was a concise strategy that showed good precision in the kinetics fitting.The activation energy for this ketalization reaction was evaluated to be 28.2 kJ·mol^-1.In addition,the kinetics of the reaction at a temperature exceeding the boiling point of acetone were also studied.We believe that all the results are important for further development of a technology for the continuous synthesis of solketal.展开更多
An inexpensive Fe doped aluminoborate consisted of 18% Fe in PKU-1 material that exhibits high selectivity of 4-hydroxymethy-2,2-dimethyl^(-1),3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h-1), and r...An inexpensive Fe doped aluminoborate consisted of 18% Fe in PKU-1 material that exhibits high selectivity of 4-hydroxymethy-2,2-dimethyl^(-1),3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h-1), and recyclable ability in the ketalization of glycerol to Solketal with acetone at 318 K has been developed. Our study demonstrated that the structure of Fe (less agglomerated iron species vs. FeO clusters) can be tuned by changing Fe loading in the PKU-1 material, which correlated well with experimental observations. Furthermore, the surface boron sites were promoted by iron loading and behaved as Lewis-acid sites to facilitate the reaction process of glycerol ketalization, while the Solketal selectivity was closely related with the structure of iron species in PKU-1, which was proved by kinetic studies, density function theory (DFT) calculations, and a series of spectroscopy studies. This investigation demonstrates that the surface B sites can play important roles in the reaction instead of being spectators.展开更多
Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal s...Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.展开更多
The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-di...The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-difluorinated cyclo-propanesunder transition-metal free and basic conditions has been developed. A broad range of gem-difluorinated cyclopro-panesand alcohols are amenable in present reaction to permit the synthesis of corresponding products in high yields. The reaction is elucidated to proceed via elimination and addition other than direct substitution based on the mechanistic studies. This transformation not only provides a new strategy for the construction of cyclopropanone ketals, but also reveals a new paradigm on C—F bond transformation without ring-opening of gem-difluorinated cyclopropanes.展开更多
Herein,we report the dynamic kinetic resolution asymmetric acylation ofγ-hydroxy-γ-perfluoroalkyl butenolides/phthalides catalyzed by amino acid-derived bifunctional organocatalysts,and a series of ketals were obtai...Herein,we report the dynamic kinetic resolution asymmetric acylation ofγ-hydroxy-γ-perfluoroalkyl butenolides/phthalides catalyzed by amino acid-derived bifunctional organocatalysts,and a series of ketals were obtained in high yields(up to 95%)and excellent enantioselectivities(up to 99%).In terms of synthetic utility,the reaction can be performed on a gram scale,and the product can be converted into potential biological nucleoside analog.展开更多
A novel carbon based strong solid acid catalyst has been synthesized successfully. The catalytic activity for acetalization and ketalization was investigated. The results showed that the novel catalyst was very effici...A novel carbon based strong solid acid catalyst has been synthesized successfully. The catalytic activity for acetalization and ketalization was investigated. The results showed that the novel catalyst was very efficient with the average yield over 92%. The novel heterogeneous catalyst also has the advantages of high activity, wide applicability even to the preparation of 7 membered ring acetals and ketals, strikingly simple workup procedure, non-pollution and reusability, which will contribute to the green process greatly.展开更多
MnSAPO-34 molecular sieves were synthesized by vapor-phase transport （VPT） method using triethylamine （Et3N） as a structure directing agent （SDA）, and were characterized by XRD, BET, SEM, UV-Vis, FT-IR, and TG a...MnSAPO-34 molecular sieves were synthesized by vapor-phase transport （VPT） method using triethylamine （Et3N） as a structure directing agent （SDA）, and were characterized by XRD, BET, SEM, UV-Vis, FT-IR, and TG analy- ses. The influence of the zeolite crystallization conditions and the dry-gel composition were investigated. The results showed that the synthesis conditions had an effect on the crystalline phase. Pure MnSAPO-34 had been obtained when it was crystallized at 140 C for 18 hours. The ratio of MnO/A1203 in the starting gel ranging from 0.1 to 0.2 resulted in pure MnSAPO-34 with a CHA topology. Beyond this scope, MnSAPO-5 with an AFI topology structure was obtained as an impurity substance. UV-Vis spectroscopy and FT-IR spectroscopy study indicated that manganese was incorporated into the framework of the molecular sieve. The catalytic performance of MnSAPO-34 molecular sieve was tested by ketalization reaction of l, 2-propanediol with cyclohexanone. High yield of cyclohexanone-1, 2-propanediol ketal was obtained.展开更多
A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solv...A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solvent and sulfonation. Physical characterization was detected to show that the carbon-based acid is amorphous with polycyclic aromatic carbon sheets attached plentiful -OH, -COOH, and -SO3H groups. The sulfonic acid density and total acid density of it reached 2.05 mmol·g-1 and 5.63 mmol·g-1, respectively by acid-base titration. As a solid acid catalyst, it showed excellent performance in the ketalization of cyclohexanone with glycol.展开更多
A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in th...A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in the presence of H_(4)SiW_(12)O_(40)/PAn The factorsinfluencing tlie synthesis were discussed and the best conditions were found out.The optimumconditions are:molar ratio of cyclohexanone to 1,2-propanediol is 1:1.4,the quantity of catalystis equal to 1.0 percent of feed stocks,and the reaction time is 40 min.H_(4)SiW_(12)O_(40)/PAn is anexcellent catalyst for synthesizing cyclohexanone 1,2-propanediol ketal and its yield can reachover 96.5 percent.展开更多
A new environmental friendly catalyst H3PW12O40/PAn was prepared and identified by means of FT-IR,XRD,and TG/DTA.The optimum conditions have been found;that is,the mass ratio of PAn to H3PW12O40 is 1：1.5,the volume o...A new environmental friendly catalyst H3PW12O40/PAn was prepared and identified by means of FT-IR,XRD,and TG/DTA.The optimum conditions have been found;that is,the mass ratio of PAn to H3PW12O40 is 1：1.5,the volume of methanol is 20 mL,and the reflux reaction time is 3 h.The structural identity of Keggin units is preserved after the incorporation into polyaniline matrix.Catalytic activities of H3PW12O40/PAn in synthesizing 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,cyclohexanone ethylene ketal,cyclohexanone 1,2-propanediol ketal,butanone ethylene ketal,butanone 1,2-propanediol ketal,2-phenyl-1,3-dioxolane,4-methyl-2-phenyl-1,3-dioxolane,2-propyl-1,3-dioxolane,and 4-methyl-2-propyl-1,3-dioxolane were reported.It has been demon-strated that H3PW12O40/PAn is an excellent catalyst.Various factors concerned in these reactions were investigated.The optimum conditions are as follows：the molar ratio of aldehyde/ketone to glycol（r） is 1：1.5,the mass ratio of the catalyst used to the reactants is 0.6%,and the reaction time is 1.0 h.Under these conditions,the yield is as follows：2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,69.0%;2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,79.5%;cyclohexanone ethylene ketal,78.9%;cyclohexanone 1,2-propanediol ketal,85.3%;butanone ethylene ketal,56.9%;butanone 1,2-propanediol ketal,78.1%;2-phenyl-1,3-dioxolane,76.3%;4-methyl-2-phenyl-1,3-dioxolane,94.2%;2-propyl-1,3-dioxolane,70.7%;and 4-methyl-2-propyl-1,3-dioxolane,79.2%.展开更多
Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl- 1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane, cyclohexanone ethylene ketal, cycl...Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl- 1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane, cyclohexanone ethylene ketal, cyclohexanone 1,2-propa- nediol ketal, butanone ethylene ketal, butanone 1,2-propanediol ketal, 2-phenyl-1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 4-methyl-2-propyl-1,3-dioxolane was reported. It has been demonstrated that activated carbon supported tungstosilicic acid is an excellent catalyst. Various factors involved in these reactions were investigated. The optimum conditions found were: molar ratio of aldehyde/ketone to glycol is 1/1.5, mass ratio of the catalyst used to the reactants is 1.0%, and reaction time is 1.0 h. Under these conditions, the yield of 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane is 61.5%, of 2,4-dimethyl- 2-ethoxycarbonylmethyl-1,3-dioxolane is 69.1%, of cyclohexanone ethylene ketal is 74.6%, of cyclohexanone 1,2-propanediol ketal is 80.1%, of butanone ethylene ketal is 69.5%, of butanone 1,2-propanediol ketal is 78.5%, of 2-phenyl-1,3-dioxolane is 56.7%, of 4-methyl-2-phenyl-1,3-dioxolane is 86.2%, of 2-propyl-1,3-dioxolane is 87.5%, of 4-methyl-2-propyl-1,3-dioxolane is 87.9%.展开更多
Tungstophosphoric acid （HPW） catalyst supported on the neural alumina was studied. It was prepared by means of an equilibrium and incipient wetness impregnation technique. Solution of HPW in 50% V/V ethanol-water wa...Tungstophosphoric acid （HPW） catalyst supported on the neural alumina was studied. It was prepared by means of an equilibrium and incipient wetness impregnation technique. Solution of HPW in 50% V/V ethanol-water was used to impregnate Al2O3 at 25℃. It was found that the catalyst containing 30% PW by calcination at 500℃ showed a higher catalytic activity in the synthesis of acetals and/or ketals. In the following condition, that is, the molar ratio of aldehyde/ketone to glycol being 1：1.5, the mass fraction of the catalyst used was 0.5%, and the reaction time was 1.0 h; the yields of ketals and acetals could reach up to 60.5%-86.7%. Moreover, it could be easily recovered and reused.展开更多
Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ...Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ^1H NMR spectra. The results indicated that the catalyst showed excellent catalytic activity for the condensation reactions. The yield of 12 classes of acetals and ketals reached 56.3%-96.3% under the typical reaction conditions （the molar ratio of aldehyde/ketone and glycol was 1：1.5, the quantity of catalyst was 0.5% of feed stock, the reaction time was 1.0 h, and the reaction temperature was 80-116℃）. The catalyst was easily recovered and reused to give almost the same yield of the product as that given by fresh TiSiW12O10/TiO2.展开更多
A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reac...A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reaction time of 2 h at reflux. It was used in catalytic synthesis of ten important ketals and acetals with a high catalytic activity. With an aldehyde/ketone to glycol molar ratio of 1 ： 1.5 and a 1 wt% catalyst loading, the yields of ketals and acetals could reach 60.0%- 93.8 % after 1 h.展开更多
Photoinitiated crosslinking of ethylene-propylene-diene terpolymer （EPDM） blends filled with calcium carbonate, talc and calcined kaolin （CK） in the presence of benzil dimethyl ketal as photoinitiator and trimethy...Photoinitiated crosslinking of ethylene-propylene-diene terpolymer （EPDM） blends filled with calcium carbonate, talc and calcined kaolin （CK） in the presence of benzil dimethyl ketal as photoinitiator and trimethylolpropane triacrylate as crosslinker and their related properties have been studied by different analytical methods, The results from gel content and heat extension determination show that the efficiency ofphotocrosslinking of EPDM increases with increasing the content of diene and its molecular weight. The EPDM blends with 100 phr different inorganic fillers can be photocrosslinked to gel content of above 60% by 5 s UV-irradiation under optimum conditions. Under the same conditions of irradiation, the orders of photocrosslinking rate and final gel content are EPDM/CaCO3 〉 EPDM/talc 〉 EPDM/CK. The data from thermogravimetric analysis, dynamic mechanical thermal analysis, electrical properties, mechanical tests and scanning electron microscopy show that UV irradiation crosslinking apparently enhances the thermal stability, mechanical properties and electrical properties of the photocrosslinked EPDM/inorganic filler samples. Although the attenuated total-reflection FTIR data show that inorganic fillers can promote the surface photo-oxidation of EPDM/inorganic filler samples with increasing the irradiation time, the above related properties of the photocrosslinked EPDM blends irradiated within 5 s are enough to satisfy many applications in the cable industry.展开更多
Bacterial surface glycans perform a diverse and important set of biological roles,and have been widely used in the treatment of bacterial infectious diseases.The majority of bacterial surface glycans are decorated wit...Bacterial surface glycans perform a diverse and important set of biological roles,and have been widely used in the treatment of bacterial infectious diseases.The majority of bacterial surface glycans are decorated with diverse rare functional groups,including amido,acetamidino,carboxamido and pyruvate groups.These functional groups are thought to be important constituents for the biological activities of glycans.Chemical synthesis of glycans bearing these functional groups or their variants is essential for the investigation of structure-activity relationships by a medicinal chemistry approach.To date,a broad choice of synthetic methods is available for targeting the different rare functional groups in bacterial surface glycans.This article reviews the structures of naturally occurring rare functional groups in bacterial surface glycans,and the chemical methods used for installation of these groups.展开更多
A new environmental friendly catalyst,HaSiWrMo6O40/PAn was prepared and identified by means of FT-IR,XRD and TG/DTA.The optimum conditions have been found,that was,mass ratio of m(PAn):m(HaSiW6Mo6On.)was 1:1.25,volume...A new environmental friendly catalyst,HaSiWrMo6O40/PAn was prepared and identified by means of FT-IR,XRD and TG/DTA.The optimum conditions have been found,that was,mass ratio of m(PAn):m(HaSiW6Mo6On.)was 1:1.25,volume of methanol was 20 mL,and the reflux reaction time was 2h.The structural identity of Keggin units was preserved after the incorporation into polyaniline matrix.H4SiW6Mo6040/PAn was used as catalyst in catalytic synthesis of acetals and ketals.Effects of n(aldehyde(ketone)):n(glycol),catalyst dosage and reaction time on yield were investingated.Optimal conditions were:n(aldehyde(ketone)):n(glycol)=1.0:1.5;mass fraction of catalyst to reactants,0.5%;reaction time,1.0 h and cyclohexane as water-stripped reagent,15 mL.Under these conditions,yields of actels and ketals were 31.9%-91.6%.展开更多
A new environmental friendly catalyst, H3PW6Mo6O40/TiO2 was prepared. The optimum conditions have been found, that is, mass ratio of m （TiO2）： m （H3PW6Mo6O40） is 1：2.0, volume of water is 30 mL, the reflux react...A new environmental friendly catalyst, H3PW6Mo6O40/TiO2 was prepared. The optimum conditions have been found, that is, mass ratio of m （TiO2）： m （H3PW6Mo6O40） is 1：2.0, volume of water is 30 mL, the reflux reaction time is 2 h, and activated temperature is 150 ℃. H3PW6Mo6O40/TiO2 was used as catalyst in catalytic synthesis ofacetals and ketals. Effects ofn （aldehyde（ketone））： n （glycol）, catalyst dosage and reaction time on yield were investigated. Optimal conditions were： n（aldehyde （ketone））： n （glycol）=1.0 ： 1.4; mass fraction of catalyst to reactants, 0.8%; reaction time, 1.0 h and cyclohexane as water-stripped reagent, 10 mL. Under these conditions, yields of acetals and ketals can reach 53.0% -86.9 0%展开更多
The acetalization of a series of carbonyl compounds with ethanediolwas performed over two self-steaxned HY zeolle catalpsts' The acetal and ketaiproducts were obtained with high ytelds Espectw, the HY zeollte with...The acetalization of a series of carbonyl compounds with ethanediolwas performed over two self-steaxned HY zeolle catalpsts' The acetal and ketaiproducts were obtained with high ytelds Espectw, the HY zeollte with highfraxnework Si/A1 ratio was proven to be suitable cataipst for the acetabotion ofunsaturated carbonyl compounds, during which the C =C double bond was notperturbed展开更多
基金the National Key Research and development Program of China(2017YFB0307302)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The ketalization of glycerol with acetone was conducted over an ionic liquid[P(C4H9)3C14H29][TsO](TTPT)in a batch reactor.A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a maximum solketal yield of 86%is achieved at acetone/glycerol molar ratio of 6/1,reaction time of 0.5 h,reaction temperature of 303 K,catalyst amount of 5 wt%of glycerol.TTPT was recycled and reused for ten times without obvious losses in terms of quantity and activity.Furthermore,effects of various experimental parameters(stirring speed,catalyst loadings,temperature and reactant composition)on the reaction kinetics are investigated.In terms of kinetics modeling,Kγis fitted by reactant composition at the temperature range 298 K–323 K,which was a concise strategy that showed good precision in the kinetics fitting.The activation energy for this ketalization reaction was evaluated to be 28.2 kJ·mol^-1.In addition,the kinetics of the reaction at a temperature exceeding the boiling point of acetone were also studied.We believe that all the results are important for further development of a technology for the continuous synthesis of solketal.
基金financially supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission (Nos. KJQN202000823 and KJZD-K201900802)Research project of Chongqing Technology and Business University(No. 1956058)+2 种基金Scientific Platform ProjectMinistry of Education (No. fykf201905)US Department of Energy Office of Basic Energy Sciences,Division of Chemical,Biological and Geological Sciences (No. DE-FG02-86ER13622.A000) for support of this research。
文摘An inexpensive Fe doped aluminoborate consisted of 18% Fe in PKU-1 material that exhibits high selectivity of 4-hydroxymethy-2,2-dimethyl^(-1),3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h-1), and recyclable ability in the ketalization of glycerol to Solketal with acetone at 318 K has been developed. Our study demonstrated that the structure of Fe (less agglomerated iron species vs. FeO clusters) can be tuned by changing Fe loading in the PKU-1 material, which correlated well with experimental observations. Furthermore, the surface boron sites were promoted by iron loading and behaved as Lewis-acid sites to facilitate the reaction process of glycerol ketalization, while the Solketal selectivity was closely related with the structure of iron species in PKU-1, which was proved by kinetic studies, density function theory (DFT) calculations, and a series of spectroscopy studies. This investigation demonstrates that the surface B sites can play important roles in the reaction instead of being spectators.
文摘Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.
文摘The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-difluorinated cyclo-propanesunder transition-metal free and basic conditions has been developed. A broad range of gem-difluorinated cyclopro-panesand alcohols are amenable in present reaction to permit the synthesis of corresponding products in high yields. The reaction is elucidated to proceed via elimination and addition other than direct substitution based on the mechanistic studies. This transformation not only provides a new strategy for the construction of cyclopropanone ketals, but also reveals a new paradigm on C—F bond transformation without ring-opening of gem-difluorinated cyclopropanes.
基金supported by the National Natural Science Foundation of China(Nos.82130103,82151525 and 81903465)the Central Plains Scholars and Scientists Studio Fund(2018002)+1 种基金the Natural Science Foundation of Henan Province(No.212300410051)the Science and Technology Major Project of Henan Province(No.221100310300)。
文摘Herein,we report the dynamic kinetic resolution asymmetric acylation ofγ-hydroxy-γ-perfluoroalkyl butenolides/phthalides catalyzed by amino acid-derived bifunctional organocatalysts,and a series of ketals were obtained in high yields(up to 95%)and excellent enantioselectivities(up to 99%).In terms of synthetic utility,the reaction can be performed on a gram scale,and the product can be converted into potential biological nucleoside analog.
文摘A novel carbon based strong solid acid catalyst has been synthesized successfully. The catalytic activity for acetalization and ketalization was investigated. The results showed that the novel catalyst was very efficient with the average yield over 92%. The novel heterogeneous catalyst also has the advantages of high activity, wide applicability even to the preparation of 7 membered ring acetals and ketals, strikingly simple workup procedure, non-pollution and reusability, which will contribute to the green process greatly.
基金supported by the Key Laboratory of Fine Chemicals,Jiangsu Provincefinancially supported by the Jiangsu Province Science and Technology Support Program (BE2011651)the Key University Science Research Project of Jiangsu Province (11KJA610002)
文摘MnSAPO-34 molecular sieves were synthesized by vapor-phase transport （VPT） method using triethylamine （Et3N） as a structure directing agent （SDA）, and were characterized by XRD, BET, SEM, UV-Vis, FT-IR, and TG analy- ses. The influence of the zeolite crystallization conditions and the dry-gel composition were investigated. The results showed that the synthesis conditions had an effect on the crystalline phase. Pure MnSAPO-34 had been obtained when it was crystallized at 140 C for 18 hours. The ratio of MnO/A1203 in the starting gel ranging from 0.1 to 0.2 resulted in pure MnSAPO-34 with a CHA topology. Beyond this scope, MnSAPO-5 with an AFI topology structure was obtained as an impurity substance. UV-Vis spectroscopy and FT-IR spectroscopy study indicated that manganese was incorporated into the framework of the molecular sieve. The catalytic performance of MnSAPO-34 molecular sieve was tested by ketalization reaction of l, 2-propanediol with cyclohexanone. High yield of cyclohexanone-1, 2-propanediol ketal was obtained.
文摘A carbon-based solid acid with high acid density was successfully prepared using camphor tree branches as raw materials through a novel method including dilute sulfuric acid activation, carbonization in refluxing solvent and sulfonation. Physical characterization was detected to show that the carbon-based acid is amorphous with polycyclic aromatic carbon sheets attached plentiful -OH, -COOH, and -SO3H groups. The sulfonic acid density and total acid density of it reached 2.05 mmol·g-1 and 5.63 mmol·g-1, respectively by acid-base titration. As a solid acid catalyst, it showed excellent performance in the ketalization of cyclohexanone with glycol.
基金supported by the National Natural Science Foundation of China(No.20471044)the Natu-ral Science Foundation of Hubei Province Education Comminee(Nos.2004D007 and 2002A00008).
文摘A new environmental friendly catalyst,H_(4)SiW_(12)O_(40)/PAn was prepared andidentified by means of FT-IR,XRD and TG/DTA.Cyclohexanone 1,2-propanediol ketal was synthesizedfrom cyclohexanone and 1,2-propanediol in the presence of H_(4)SiW_(12)O_(40)/PAn The factorsinfluencing tlie synthesis were discussed and the best conditions were found out.The optimumconditions are:molar ratio of cyclohexanone to 1,2-propanediol is 1:1.4,the quantity of catalystis equal to 1.0 percent of feed stocks,and the reaction time is 40 min.H_(4)SiW_(12)O_(40)/PAn is anexcellent catalyst for synthesizing cyclohexanone 1,2-propanediol ketal and its yield can reachover 96.5 percent.
基金supported by the Natural Science Foundation of Hubei Province,China(No.2005ABA053)Hubei Key Laboratory of Bioanalytical Technique,and the National Natural Science Foundation of China(No.20471044).
文摘A new environmental friendly catalyst H3PW12O40/PAn was prepared and identified by means of FT-IR,XRD,and TG/DTA.The optimum conditions have been found;that is,the mass ratio of PAn to H3PW12O40 is 1：1.5,the volume of methanol is 20 mL,and the reflux reaction time is 3 h.The structural identity of Keggin units is preserved after the incorporation into polyaniline matrix.Catalytic activities of H3PW12O40/PAn in synthesizing 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,cyclohexanone ethylene ketal,cyclohexanone 1,2-propanediol ketal,butanone ethylene ketal,butanone 1,2-propanediol ketal,2-phenyl-1,3-dioxolane,4-methyl-2-phenyl-1,3-dioxolane,2-propyl-1,3-dioxolane,and 4-methyl-2-propyl-1,3-dioxolane were reported.It has been demon-strated that H3PW12O40/PAn is an excellent catalyst.Various factors concerned in these reactions were investigated.The optimum conditions are as follows：the molar ratio of aldehyde/ketone to glycol（r） is 1：1.5,the mass ratio of the catalyst used to the reactants is 0.6%,and the reaction time is 1.0 h.Under these conditions,the yield is as follows：2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,69.0%;2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,79.5%;cyclohexanone ethylene ketal,78.9%;cyclohexanone 1,2-propanediol ketal,85.3%;butanone ethylene ketal,56.9%;butanone 1,2-propanediol ketal,78.1%;2-phenyl-1,3-dioxolane,76.3%;4-methyl-2-phenyl-1,3-dioxolane,94.2%;2-propyl-1,3-dioxolane,70.7%;and 4-methyl-2-propyl-1,3-dioxolane,79.2%.
基金Project supported by the Natural Science Foundation of HubeiProvince Education Committee (No. 2004D007) and the NationalNatural Science Foundation of China (No. 20471044)
文摘Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl- 1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane, cyclohexanone ethylene ketal, cyclohexanone 1,2-propa- nediol ketal, butanone ethylene ketal, butanone 1,2-propanediol ketal, 2-phenyl-1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 4-methyl-2-propyl-1,3-dioxolane was reported. It has been demonstrated that activated carbon supported tungstosilicic acid is an excellent catalyst. Various factors involved in these reactions were investigated. The optimum conditions found were: molar ratio of aldehyde/ketone to glycol is 1/1.5, mass ratio of the catalyst used to the reactants is 1.0%, and reaction time is 1.0 h. Under these conditions, the yield of 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane is 61.5%, of 2,4-dimethyl- 2-ethoxycarbonylmethyl-1,3-dioxolane is 69.1%, of cyclohexanone ethylene ketal is 74.6%, of cyclohexanone 1,2-propanediol ketal is 80.1%, of butanone ethylene ketal is 69.5%, of butanone 1,2-propanediol ketal is 78.5%, of 2-phenyl-1,3-dioxolane is 56.7%, of 4-methyl-2-phenyl-1,3-dioxolane is 86.2%, of 2-propyl-1,3-dioxolane is 87.5%, of 4-methyl-2-propyl-1,3-dioxolane is 87.9%.
基金This work was supported in part by the Combined Project between the Educational Commission and the Economic Com-mission of Gansu Province (No. 99CX-04)the Natural Science Foundation of Gansu Province (No. 3ZS041-A25-028),the Invention Project of Science & Technology, China (No. KJCXGC-01, NWNU).
文摘Tungstophosphoric acid （HPW） catalyst supported on the neural alumina was studied. It was prepared by means of an equilibrium and incipient wetness impregnation technique. Solution of HPW in 50% V/V ethanol-water was used to impregnate Al2O3 at 25℃. It was found that the catalyst containing 30% PW by calcination at 500℃ showed a higher catalytic activity in the synthesis of acetals and/or ketals. In the following condition, that is, the molar ratio of aldehyde/ketone to glycol being 1：1.5, the mass fraction of the catalyst used was 0.5%, and the reaction time was 1.0 h; the yields of ketals and acetals could reach up to 60.5%-86.7%. Moreover, it could be easily recovered and reused.
基金This work was financially supported by the Natural Science Foundation of Hubei Province, China (No. 2005ABA053) and the National Natural Science Foundation of China (No. 20471044).
文摘Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ^1H NMR spectra. The results indicated that the catalyst showed excellent catalytic activity for the condensation reactions. The yield of 12 classes of acetals and ketals reached 56.3%-96.3% under the typical reaction conditions （the molar ratio of aldehyde/ketone and glycol was 1：1.5, the quantity of catalyst was 0.5% of feed stock, the reaction time was 1.0 h, and the reaction temperature was 80-116℃）. The catalyst was easily recovered and reused to give almost the same yield of the product as that given by fresh TiSiW12O10/TiO2.
基金Funded by the Natural Science Foundation of Hubei Province (No.2005ABA053)Hubei Key Laboratory of Pollutant Analysis & Reuse Technologythe National Natural Science Foundation of China (No. 20471044)
文摘A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reaction time of 2 h at reflux. It was used in catalytic synthesis of ten important ketals and acetals with a high catalytic activity. With an aldehyde/ketone to glycol molar ratio of 1 ： 1.5 and a 1 wt% catalyst loading, the yields of ketals and acetals could reach 60.0%- 93.8 % after 1 h.
基金supported by the National Natural Science Foundation of China(No.20704040)
文摘Photoinitiated crosslinking of ethylene-propylene-diene terpolymer （EPDM） blends filled with calcium carbonate, talc and calcined kaolin （CK） in the presence of benzil dimethyl ketal as photoinitiator and trimethylolpropane triacrylate as crosslinker and their related properties have been studied by different analytical methods, The results from gel content and heat extension determination show that the efficiency ofphotocrosslinking of EPDM increases with increasing the content of diene and its molecular weight. The EPDM blends with 100 phr different inorganic fillers can be photocrosslinked to gel content of above 60% by 5 s UV-irradiation under optimum conditions. Under the same conditions of irradiation, the orders of photocrosslinking rate and final gel content are EPDM/CaCO3 〉 EPDM/talc 〉 EPDM/CK. The data from thermogravimetric analysis, dynamic mechanical thermal analysis, electrical properties, mechanical tests and scanning electron microscopy show that UV irradiation crosslinking apparently enhances the thermal stability, mechanical properties and electrical properties of the photocrosslinked EPDM/inorganic filler samples. Although the attenuated total-reflection FTIR data show that inorganic fillers can promote the surface photo-oxidation of EPDM/inorganic filler samples with increasing the irradiation time, the above related properties of the photocrosslinked EPDM blends irradiated within 5 s are enough to satisfy many applications in the cable industry.
基金This work was supported by the National Natural Science Foundation of China(Nos.22077052,21877052,21907039,22107037)China Postdoctoral Science Foundation(2020M681487,2021M691279)+4 种基金the National Key R&D Program of China(2020YFA0908304)the Natural Science Foundation of Jiangsu Province(BK20180030,BK20190575)the National First-class Discipline Program of Light Industry Technology and Engineering(LITE2018-14)the 111 Project(111-2-06)the Open Project of Key Laboratory of Carbohydrate Chemistry and Biotechnology(Jiangnan University),Ministry of Education(KLCCB-KF202005).
文摘Bacterial surface glycans perform a diverse and important set of biological roles,and have been widely used in the treatment of bacterial infectious diseases.The majority of bacterial surface glycans are decorated with diverse rare functional groups,including amido,acetamidino,carboxamido and pyruvate groups.These functional groups are thought to be important constituents for the biological activities of glycans.Chemical synthesis of glycans bearing these functional groups or their variants is essential for the investigation of structure-activity relationships by a medicinal chemistry approach.To date,a broad choice of synthetic methods is available for targeting the different rare functional groups in bacterial surface glycans.This article reviews the structures of naturally occurring rare functional groups in bacterial surface glycans,and the chemical methods used for installation of these groups.
文摘A new environmental friendly catalyst,HaSiWrMo6O40/PAn was prepared and identified by means of FT-IR,XRD and TG/DTA.The optimum conditions have been found,that was,mass ratio of m(PAn):m(HaSiW6Mo6On.)was 1:1.25,volume of methanol was 20 mL,and the reflux reaction time was 2h.The structural identity of Keggin units was preserved after the incorporation into polyaniline matrix.H4SiW6Mo6040/PAn was used as catalyst in catalytic synthesis of acetals and ketals.Effects of n(aldehyde(ketone)):n(glycol),catalyst dosage and reaction time on yield were investingated.Optimal conditions were:n(aldehyde(ketone)):n(glycol)=1.0:1.5;mass fraction of catalyst to reactants,0.5%;reaction time,1.0 h and cyclohexane as water-stripped reagent,15 mL.Under these conditions,yields of actels and ketals were 31.9%-91.6%.
基金Acknowledgements： This work was financially supported by the Natural Science Foundation of Hubei Province, China （No. 2005ABA053） and the National Natural Science Foundation of China （No. 20471044）.
文摘A new environmental friendly catalyst, H3PW6Mo6O40/TiO2 was prepared. The optimum conditions have been found, that is, mass ratio of m （TiO2）： m （H3PW6Mo6O40） is 1：2.0, volume of water is 30 mL, the reflux reaction time is 2 h, and activated temperature is 150 ℃. H3PW6Mo6O40/TiO2 was used as catalyst in catalytic synthesis ofacetals and ketals. Effects ofn （aldehyde（ketone））： n （glycol）, catalyst dosage and reaction time on yield were investigated. Optimal conditions were： n（aldehyde （ketone））： n （glycol）=1.0 ： 1.4; mass fraction of catalyst to reactants, 0.8%; reaction time, 1.0 h and cyclohexane as water-stripped reagent, 10 mL. Under these conditions, yields of acetals and ketals can reach 53.0% -86.9 0%
文摘The acetalization of a series of carbonyl compounds with ethanediolwas performed over two self-steaxned HY zeolle catalpsts' The acetal and ketaiproducts were obtained with high ytelds Espectw, the HY zeollte with highfraxnework Si/A1 ratio was proven to be suitable cataipst for the acetabotion ofunsaturated carbonyl compounds, during which the C =C double bond was notperturbed
