A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones w...A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.展开更多
A novel environmental friendly catalyst, H3PW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of butyraldehyde glycol acetal catalyzed by H3P...A novel environmental friendly catalyst, H3PW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of butyraldehyde glycol acetal catalyzed by H3PW12O40/MCM-48 was studied with butyraldehyde and glycol as reactants. H3PW12O40/MCM-48 was an excellent catalyst for the synthesizing butyraldehyde glycol acetal and Keggin structure of H3PW12O40 kept unchanged after being impregnated on surface of the molecular sieve support. Effects of n（butyraldehyde）： n（glycol）, catalyst dosage, cyclohexane（water-stripped reagent） and reaction time on yields of the product were investigated. The optimum conditions had been found, that was, molar ratio of butyraldehyde to glycol was 1： 1.6, mass ratio of catalyst used to the reactants was 0.25% and reaction time was 75 min. Under these conditions, the yield of butyraldehyde glycol acetal can reach 79.74%.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
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
Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral root...Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral roots of Aconitum carmichaelii.Their structures were elucidated by extensive spectroscopic data analysis.Compounds 1-3 represent the first examples of napelline-type C20 diterpenoid alkaloid alcohol iminiums,of which the structures were fully characterized.In addition,transformation and equilibration between the alcohol iminiums（1-3） and the aza acetals la-3a were investigated by measurements of the NMR spectra in protic and aprotic deuterium solvents including alkali pyridine-d5,along with evaporation under reduced pressure and gradual additions of TFA,AcOH,and HC1.The results demonstrated that the transformation and equilibration were solvent-,base-,and acid-dependent.Especially,in aqueous biological fluid,these C20-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions.The absolute configurations of 1-3 were confirmed by X-ray crystallographic analysis of 2a.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
SO_4^(2-)/TiO_(2)-WO_(3)was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction.The optimum conditions ar...SO_4^(2-)/TiO_(2)-WO_(3)was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction.The optimum conditions are found that the mass fraction of H_2WO_4 used in thecompound is 12.5 percent,the calcination temperature is 580 deg C,the calcination time is 3 h,andthe soaked consistency of H_2SO_4 is 1.0 mol centre dot L^(-1).Then SO_4^(2-)/TiO_(2)-WO_(3)wasapplied as the catalyst in the catalytic synthesis of eight similar important ketals and acetalsunder the optimum conditions and revealed high catalytic activity.On condition that the molar ratioof aldehyde/ketone to glycol is 1:1.5,the mass fraction of the catalyst used in the reactants is0.5 percent,and the reaction time is 1.0 h,the yields of ketals and acetals can reach 64.2percent-95.1 percent.Moreover,it can be easily recovered and reused.展开更多
SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The...SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The optimum conditions were also found, that is, the mass ratio of MoO3 used in the compound is 25%, the calcination temperature 450℃, and the soaked consistency of H2SO4 is 0.5mol.L^-1. Then it was applied in the catalytic synthesis of six similar important ketals and acetals as catalyst and revealed high catalytic activity. Under the condition that the molar ratio of aldehyde/ketone to glycol was 1:1.5, the mass ratio of the catalyst to the reactants was 0.5% and the reaction time 1.0 h, the yield of ketals and acetals reached up to 63.2%. The catalyst can be easily recovered and reused.展开更多
The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out....The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out. High conversion （≥98%） and specific selectivity were obtained using the novel carbon based acid, which kept high activity after it was reused 5 times. Moreover. the catalyst could be used to catalyze the acetalization and ketalization of different aldehydes and ketones with superior yield. The yield of several products was over 90%. The novel heterogeneous catalyst has the distinct advantages of high activity, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the success of the green process greatly.展开更多
[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separa...[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.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
A new rapid synthetic method is described for synthesis of a, a-dibenzylidene- cycloalkanones by the reaction of acetals and cycloalkanones without solvent using BF3稥t2O as catalyst under microwave irradiation.
The novel solid acid with both sulfonic and carbonyl acid groups has been synthesized from 3-((2-sulfoethoxy) carbonyl)acrylic acid and tetraethyl orthosilicate(TEOS). The catalytic activities were investigated throug...The novel solid acid with both sulfonic and carbonyl acid groups has been synthesized from 3-((2-sulfoethoxy) carbonyl)acrylic acid and tetraethyl orthosilicate(TEOS). The catalytic activities were investigated through the acetalization. The results showed that the novel solid acid was very efficient for the reactions with the high yields. The high acidity, high stability and reusability were the key feature of the novel solid acid. Moreover, the sulfonic and carbonyl acid groups could cooperate during the catalytic process, which improved its catalytic activities. The catalyst shows recyclability, and hold great potential for replacement of homogeneous catalysts.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
Vanillin 1, 2-propylene glycol acetal was synthesized from vanillin and 1, 2-propylene glycol using H3PMo6W6O40·nH2O as catalyst, The factors influencing the synthesis were discussed and the better reaction condi...Vanillin 1, 2-propylene glycol acetal was synthesized from vanillin and 1, 2-propylene glycol using H3PMo6W6O40·nH2O as catalyst, The factors influencing the synthesis were discussed and the better reaction conditions were found as follows： The amount of vanillin was 3.8 g, the molar ratio of vanillin was 1, 2-propylene glycol 1.0 to 2.4, the amount of catalyst was 1.6% in proportion to the total reacting materials, the volume ofcyclohexane as the water-carrying agent 4 mL, the refluxing time was 2 h at 88-96℃ and thus the product yield reached over 87%. The results show that the catalyst＇s activity is high and the reaction time is short.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
Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influ...Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influencing factors of the acetalation reaction e.g. the reaction time, the volume of water-carrying agent,the molar ratio of catalyst to benzaldehyde and the molar ratio of glycol to benzaldehyde had been studied.The yield of benzaldehyde glycol acetal would reach a maximum of 81.3% under the conditions approached.Six of other acetals were also synthesized. Moreover, a plausible reaction mechanism for the formation of acetal had been proposed.展开更多
文摘A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.
基金This work was financially supported by the Natural Science Foundation of Hubei Province, China （No. 2005ABA053）.
文摘A novel environmental friendly catalyst, H3PW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of butyraldehyde glycol acetal catalyzed by H3PW12O40/MCM-48 was studied with butyraldehyde and glycol as reactants. H3PW12O40/MCM-48 was an excellent catalyst for the synthesizing butyraldehyde glycol acetal and Keggin structure of H3PW12O40 kept unchanged after being impregnated on surface of the molecular sieve support. Effects of n（butyraldehyde）： n（glycol）, catalyst dosage, cyclohexane（water-stripped reagent） and reaction time on yields of the product were investigated. The optimum conditions had been found, that was, molar ratio of butyraldehyde to glycol was 1： 1.6, mass ratio of catalyst used to the reactants was 0.25% and reaction time was 75 min. Under these conditions, the yield of butyraldehyde glycol acetal can reach 79.74%.
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Financial support from the National Natural Science Foundation of China (NNSFC Nos. 21132009, 30825044)the National Science and Technology Project of China (Nos. 2012ZX09301002002, 2011ZX0 9307-002-01)
文摘Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral roots of Aconitum carmichaelii.Their structures were elucidated by extensive spectroscopic data analysis.Compounds 1-3 represent the first examples of napelline-type C20 diterpenoid alkaloid alcohol iminiums,of which the structures were fully characterized.In addition,transformation and equilibration between the alcohol iminiums（1-3） and the aza acetals la-3a were investigated by measurements of the NMR spectra in protic and aprotic deuterium solvents including alkali pyridine-d5,along with evaporation under reduced pressure and gradual additions of TFA,AcOH,and HC1.The results demonstrated that the transformation and equilibration were solvent-,base-,and acid-dependent.Especially,in aqueous biological fluid,these C20-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions.The absolute configurations of 1-3 were confirmed by X-ray crystallographic analysis of 2a.
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supported by the Natural Science Foundation of Hubei Province Education Committee(Nos.2004D007and2002A00008)the National Natural Science Foundation of China(No.20471044)
文摘SO_4^(2-)/TiO_(2)-WO_(3)was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction.The optimum conditions are found that the mass fraction of H_2WO_4 used in thecompound is 12.5 percent,the calcination temperature is 580 deg C,the calcination time is 3 h,andthe soaked consistency of H_2SO_4 is 1.0 mol centre dot L^(-1).Then SO_4^(2-)/TiO_(2)-WO_(3)wasapplied as the catalyst in the catalytic synthesis of eight similar important ketals and acetalsunder the optimum conditions and revealed high catalytic activity.On condition that the molar ratioof aldehyde/ketone to glycol is 1:1.5,the mass fraction of the catalyst used in the reactants is0.5 percent,and the reaction time is 1.0 h,the yields of ketals and acetals can reach 64.2percent-95.1 percent.Moreover,it can be easily recovered and reused.
文摘SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The optimum conditions were also found, that is, the mass ratio of MoO3 used in the compound is 25%, the calcination temperature 450℃, and the soaked consistency of H2SO4 is 0.5mol.L^-1. Then it was applied in the catalytic synthesis of six similar important ketals and acetals as catalyst and revealed high catalytic activity. Under the condition that the molar ratio of aldehyde/ketone to glycol was 1:1.5, the mass ratio of the catalyst to the reactants was 0.5% and the reaction time 1.0 h, the yield of ketals and acetals reached up to 63.2%. The catalyst can be easily recovered and reused.
基金the National Key Project ofScientific and Technical SupportingPrograms Funded by the Ministry of Science & Technology of China (No.2006BAE03B06)the Shanghai International Cooperation of Science and Technology Project (No.06SR07101).
文摘The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out. High conversion （≥98%） and specific selectivity were obtained using the novel carbon based acid, which kept high activity after it was reused 5 times. Moreover. the catalyst could be used to catalyze the acetalization and ketalization of different aldehydes and ketones with superior yield. The yield of several products was over 90%. The novel heterogeneous catalyst has the distinct advantages of high activity, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the success of the green process greatly.
基金support from Nanjing University of Science and Technology
文摘[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
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The work was supported by the National Natural Science Foundation of China (NO. 20272047) and the Northwest Normal University Science and Technology Development Foundation of China.
文摘A new rapid synthetic method is described for synthesis of a, a-dibenzylidene- cycloalkanones by the reaction of acetals and cycloalkanones without solvent using BF3稥t2O as catalyst under microwave irradiation.
基金Supported by the Chinese National General Administration of Quality Supervision,Inspection and Quarantine(2012IK048,2011IK041)the National Natural Science Foundation of China(21103111)
文摘The novel solid acid with both sulfonic and carbonyl acid groups has been synthesized from 3-((2-sulfoethoxy) carbonyl)acrylic acid and tetraethyl orthosilicate(TEOS). The catalytic activities were investigated through the acetalization. The results showed that the novel solid acid was very efficient for the reactions with the high yields. The high acidity, high stability and reusability were the key feature of the novel solid acid. Moreover, the sulfonic and carbonyl acid groups could cooperate during the catalytic process, which improved its catalytic activities. The catalyst shows recyclability, and hold great potential for replacement of homogeneous catalysts.
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%.
文摘Vanillin 1, 2-propylene glycol acetal was synthesized from vanillin and 1, 2-propylene glycol using H3PMo6W6O40·nH2O as catalyst, The factors influencing the synthesis were discussed and the better reaction conditions were found as follows： The amount of vanillin was 3.8 g, the molar ratio of vanillin was 1, 2-propylene glycol 1.0 to 2.4, the amount of catalyst was 1.6% in proportion to the total reacting materials, the volume ofcyclohexane as the water-carrying agent 4 mL, the refluxing time was 2 h at 88-96℃ and thus the product yield reached over 87%. The results show that the catalyst＇s activity is high and the reaction time is short.
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
基金Supported by the National Natural Science Foundation of China(21376265)
文摘Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influencing factors of the acetalation reaction e.g. the reaction time, the volume of water-carrying agent,the molar ratio of catalyst to benzaldehyde and the molar ratio of glycol to benzaldehyde had been studied.The yield of benzaldehyde glycol acetal would reach a maximum of 81.3% under the conditions approached.Six of other acetals were also synthesized. Moreover, a plausible reaction mechanism for the formation of acetal had been proposed.
