There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of...There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry(LC-MS). Based on the derivatization of C=C bonds with Ph I=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine(PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.展开更多
Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dis...Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dissociation energy,its strong coordination ability,and the difference between its reactivity and that of the product amines.Herein,we reported the first electrochemical protocol for direct syntheses of unprotected tetrasubstituted aziridines with NH3 and alkenes in the absence of an oxidant,which are highly challenging to achieve by other methods.The combination of graphite felt as the anode material and MeOH as the solvent was the key to the success of the protocol,and the effects of these factors were investigated by means of cyclic voltammetry and density functional theory calculations.展开更多
The urea-catalyzed aziridination of 1,2-vicinal haloamines derived from aminohalogenation of olefins has been developed. This rapid and simple method was carried out by simply grinding the solid mixture of the substra...The urea-catalyzed aziridination of 1,2-vicinal haloamines derived from aminohalogenation of olefins has been developed. This rapid and simple method was carried out by simply grinding the solid mixture of the substrate, K2CO3 and catalytic amount of urea at room temperature in air. The reaction provides a protocol for quantitative preparation of aziridines in a large scope of aminohalogenated derivatives of olefins including α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins. The possible mechanism involving an H-bond promoting deprotonation has been suggested for this reaction.展开更多
Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such...Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.展开更多
Isothiourea is an important class of sulfur-containing molecules showing unique catalytic and biological activities. As such,polyisothiourea is envisioned to be an interesting type of polymer that potentially exhibits...Isothiourea is an important class of sulfur-containing molecules showing unique catalytic and biological activities. As such,polyisothiourea is envisioned to be an interesting type of polymer that potentially exhibits a number of interesting properties. However, there is no access to synthesizing well-defined polyisothiourea, and currently isothiourea-containing polymers are mainly prepared by immobilizing onto other polymer's side chain. Herein, we report the first facile synthesis of polyisothioureas via alternating copolymerization of aziridines and isothiocayanates. Mediated by the catalytic system of phosphazene superbases/alcohol, a broad scope of aziridines and isothiocayanates could be transformed into polyisothioureas with adjustable substitutions(11 examples). The structures of obtained polyisothioureas were fully characterized with ^(1)H-NMR, ^(13)C-NMR, and ^(1)H-^(13)C HMBC NMR. Moreover, the polyisothioureas show tunable thermal properties depending on substitutions on the isothiourea linkages. The novel structure of these polyisothioureas will enable a powerful platform for the discovery of nextgeneration functional plastics.展开更多
Aziridine and its N-substituted derivatives could undergo nucleophilic ring opening reaction with biological molecules, leading to their alkylation and the loss of their biological activities. For this purpose, ethyl ...Aziridine and its N-substituted derivatives could undergo nucleophilic ring opening reaction with biological molecules, leading to their alkylation and the loss of their biological activities. For this purpose, ethyl 4-[N-methyl-N-（2,3-aziridinyl）amino] benzoate and diethyl N-{4-[N-methyl-N-（2,3-aziridinyl）amino]benzoyl}-L-glutamate, as the key intermediates in the synthesis of new anticancer agents, were designed and synthesized via four steps of reactions in good yields.展开更多
A mild and efficient method for preparation of novel 2,2-dichloro-1,3-diarylaziridines from Schiff base compounds in the presence of Ar-cetyl-N,N,N-trimethyl ammonium bromide（CTAB） as phase transfer catalyst has bee...A mild and efficient method for preparation of novel 2,2-dichloro-1,3-diarylaziridines from Schiff base compounds in the presence of Ar-cetyl-N,N,N-trimethyl ammonium bromide（CTAB） as phase transfer catalyst has been described.The reaction is dramatically enhanced in the presence of quaternary ammonium salt.The corresponding products have been obtained in excellent yields,high purity and short reaction times.展开更多
New quinolone derivatives of 7-[2-aminomethylaziridin-l-yl]quinolone-3-carboxylic acids were synthesized. The structures of these compounds were characterized by IH NMR and HRESI-MS.
(2S, 3R)-2-acetooxymethanyl-3-(P-nitrophenyl)-N-tosylaziridine 5 was synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1, 3-propanediol 1 in four steps with a 24.8% overall yield. This reaction is stereospecific and...(2S, 3R)-2-acetooxymethanyl-3-(P-nitrophenyl)-N-tosylaziridine 5 was synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1, 3-propanediol 1 in four steps with a 24.8% overall yield. This reaction is stereospecific and occurs an expectable configuration inversion at α-carbon atom of benzyl group. The structure of substituted aziridine was determined on FT-IR, NMR, MS and so on.展开更多
Macroporous resin （D201）-supported quartemary ammonium bisulfate （D201-HSO4） was prepared and effectively used in catalyzing the hydrolysis of epoxides or aziridines under mild and non-metal conditions to give the...Macroporous resin （D201）-supported quartemary ammonium bisulfate （D201-HSO4） was prepared and effectively used in catalyzing the hydrolysis of epoxides or aziridines under mild and non-metal conditions to give the corresponding 1,2-diols and β-amino alcohols in high yields. The catalyst was facilely prepared and recyclable.展开更多
Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri-n-butylphosphane （10 mol%） in the mixture of CH3CN/H20 （10：1）, giving corresponding vicinal diamines in ...Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri-n-butylphosphane （10 mol%） in the mixture of CH3CN/H20 （10：1）, giving corresponding vicinal diamines in mediate to high yields （58-95%） with good regioselectivitie, while aromatic secondary amine could not react under the same conditions. Tri-n-butylphosphane exhibited different catalytic selectivity to amines from Lewis acid catalysts.展开更多
Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent evaporation method. The results show that,a lower surface free energy with shel...Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent evaporation method. The results show that,a lower surface free energy with shell polyester is more favourable for the formation of microcapsules. Full encapsulating microcapsules are synthesized with the polyester with a surface free energy of 34.5 mJ/m2. Shell-to-core feeding mass ratio has a significant influence on the morphology and core content of the resulting microcapsules. Well defined spherical microcapsules with uniform shell thickness and core content at around 22% are produced at a shell-to-core mass ratio of 1:1. When 2.5% of colloid stabilizer is used,hollow spherical microcapsules are obtained. A high solvent evaporation rate results in wrinkling and porosity of the microcapsules,and an evaporation rate equivalent to solvent elimination in about 2 h provides a uniform rate of surface hardening. The characterization of the microcapsules by SEM and FTIR demonstrates that polyfunctional aziridine is encapsulated at the centre of the microcapsule. The microcapsules synthesized can be broken at a high shear rate.展开更多
A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content...A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content of crosslinker in the emulsion, the mechanical properties and solvent resistance of the resin will be apparently improved, but its glass transition temperature (T.) is very low. The lowest amount of crosslinker used in the acrylic resin emulsion is 0.25%. Curing kinetics studied by DSC show that this curing reaction occurs readily because the apparent activation energy of the reaction is low (65.1 kJ/mol). These results demonstrate that the aziridine crosslinker is indeed a low temperature crosslinking agent and can be used at room temperature.展开更多
A novel compound of chiral 4-hydroxy-4-butyrolactam fused aziridine was synthesized via tandem nucleophilic displacement reaction under mild condition. Its structure was determined by IR, 1H NMR, elemental analysis an...A novel compound of chiral 4-hydroxy-4-butyrolactam fused aziridine was synthesized via tandem nucleophilic displacement reaction under mild condition. Its structure was determined by IR, 1H NMR, elemental analysis and X-ray diffraction. The crystal of the new compound is of orthorhombic, space group P212121 with a = 6.4246（6）, b = 13.5081（13）, c = 18.6399（18） A, Mr = 278.39, Z = 4, V = 1617.6（3）A^3, Dc = 1.143 g/cm^3, p（MoKa） = 0.075 mm^-1, F（000） = 608, the final R = 0.0297 and wR = 0.0679.展开更多
Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as re...Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.展开更多
A Sc(OTf)3-catalyzed[3+3]cycloaddition of 2,2’-diester aziridines withβ-(indol-2-yl)-α,β-unsaturated ketones was developed,affording polysubstituted tetrahydro-y-carbolines in single diastereoisomers in good to ex...A Sc(OTf)3-catalyzed[3+3]cycloaddition of 2,2’-diester aziridines withβ-(indol-2-yl)-α,β-unsaturated ketones was developed,affording polysubstituted tetrahydro-y-carbolines in single diastereoisomers in good to excellent yields.展开更多
Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the infl...Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.展开更多
Oxidative dehydrogenative [3+3] annulation of benzylhydrazines with N-sulfonylaziridines is described.A series of complex tetrahydro-1,2,4-triazines were produced under mild reaction conditions.
Basic ion-exchange resins,one kind of polystyryl-supported tertiary amine,were demonstrated to be highly efficient and recyclable catalysts for the fixation of carbon dioxide with aziridines under mild conditions,lead...Basic ion-exchange resins,one kind of polystyryl-supported tertiary amine,were demonstrated to be highly efficient and recyclable catalysts for the fixation of carbon dioxide with aziridines under mild conditions,leading to the formation of 5-aryl-2-oxazolidinone with excellent regio-selectivities.Notably,neither solvents nor any additives were required,and the catalyst could be recovered by simple filtration and directly reused at least five times without significant loss of catalytic activity and selectivity.The present protocol has been applied to reactions of epoxides/propargyl amines with CO_(2)/CS2.This solvent-free process thus represents environmentally friendly catalytic conversion of CO_(2) into value-added chemicals and may have potential in various continuous flow reactors in industry.展开更多
Cycloaddition of CO_(2) with aziridines is an important reaction to obtain high-value products.Porous MOFs can catalyze this reaction,but co-catalysts are still necessary to improve the catalytic performance.Such a re...Cycloaddition of CO_(2) with aziridines is an important reaction to obtain high-value products.Porous MOFs can catalyze this reaction,but co-catalysts are still necessary to improve the catalytic performance.Such a reaction catalyzed by MOFs-based materials without co-catalyst has not been reported hitherto.Herein,a porous and stable three-dimensional(3D)framework{[Ni(DCTP)]·6.5DMF}_(n)(1)with a large Langmuir surface area of 3,789 m^(2)/g was synthesized,which displayed high I2 adsorption ability up to 731.0 mg/g and could release it reversibly.Additionally,it exhibited a high CO_(2) adsorption capacity of 104.0 cm^(3)/g at 273 K.The investigation results revealed 1 could effectively catalyze the cycloaddition of CO_(2) and aziridines in the absence of additional co-catalyst,and it could maintain the catalytic activity after five cycles.Furthermore,1 also exhibited high catalytic activity for the gram-scale experiment.Importantly,it is the first MOF material as a heterogeneous catalyst for the conversion of CO_(2) and aziridines without co-catalyst.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.22074111, 22004093 and 22004092)the National Key Research and Development Program of China (No.2021YFC2700700)the support of the start-up funds of Wuhan University and the National Youth Talents Plan of China。
文摘There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry(LC-MS). Based on the derivatization of C=C bonds with Ph I=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine(PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.
基金supported by the National Natural Science Foundation of China(nos.22071105,22031008,21803030,and 22001089)QingLan Project of Jiangsu Education Department,and the Jiangsu Innovation&Entrepreneurship Talents Plan in China.J.L.appreciates the support from the Nature Science Foundation of Jiangsu Province(no.BK20191046).
文摘Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dissociation energy,its strong coordination ability,and the difference between its reactivity and that of the product amines.Herein,we reported the first electrochemical protocol for direct syntheses of unprotected tetrasubstituted aziridines with NH3 and alkenes in the absence of an oxidant,which are highly challenging to achieve by other methods.The combination of graphite felt as the anode material and MeOH as the solvent was the key to the success of the protocol,and the effects of these factors were investigated by means of cyclic voltammetry and density functional theory calculations.
基金The authors are grateful to the National Natural Science Foundation of China （No. 20572066）, the Natural Science Foundation of Shaanxi Province （No. 2009JM2011）, and the Innovation Foundation of Postgraduate Cultivation of Shaanxi Normal University （No. 2008CXB009）.
文摘The urea-catalyzed aziridination of 1,2-vicinal haloamines derived from aminohalogenation of olefins has been developed. This rapid and simple method was carried out by simply grinding the solid mixture of the substrate, K2CO3 and catalytic amount of urea at room temperature in air. The reaction provides a protocol for quantitative preparation of aziridines in a large scope of aminohalogenated derivatives of olefins including α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins. The possible mechanism involving an H-bond promoting deprotonation has been suggested for this reaction.
基金the financial support provided by the National Natural Science Foundation of China(Nos.21572163 and 21873074)the Wenzhou Science&Technology Bureau(No.G20210032)。
文摘Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.
基金financially supported by the National Key R&D Program of China (No.2021YFA1501700)the Science and Technology Development Plan of Jilin Province (Nos.20230101042JC and 20210201059GX)+1 种基金Basic Science Center Program (No.51988102)the National Natural Science Foundation of China (Nos.52203017 and 52073272)。
文摘Isothiourea is an important class of sulfur-containing molecules showing unique catalytic and biological activities. As such,polyisothiourea is envisioned to be an interesting type of polymer that potentially exhibits a number of interesting properties. However, there is no access to synthesizing well-defined polyisothiourea, and currently isothiourea-containing polymers are mainly prepared by immobilizing onto other polymer's side chain. Herein, we report the first facile synthesis of polyisothioureas via alternating copolymerization of aziridines and isothiocayanates. Mediated by the catalytic system of phosphazene superbases/alcohol, a broad scope of aziridines and isothiocayanates could be transformed into polyisothioureas with adjustable substitutions(11 examples). The structures of obtained polyisothioureas were fully characterized with ^(1)H-NMR, ^(13)C-NMR, and ^(1)H-^(13)C HMBC NMR. Moreover, the polyisothioureas show tunable thermal properties depending on substitutions on the isothiourea linkages. The novel structure of these polyisothioureas will enable a powerful platform for the discovery of nextgeneration functional plastics.
基金National Natural Science Foundation of China (Grant No.20672008)985 Program of Ministry of Education of China.
文摘Aziridine and its N-substituted derivatives could undergo nucleophilic ring opening reaction with biological molecules, leading to their alkylation and the loss of their biological activities. For this purpose, ethyl 4-[N-methyl-N-（2,3-aziridinyl）amino] benzoate and diethyl N-{4-[N-methyl-N-（2,3-aziridinyl）amino]benzoyl}-L-glutamate, as the key intermediates in the synthesis of new anticancer agents, were designed and synthesized via four steps of reactions in good yields.
基金the University of Kashan research council for the partial support of this work
文摘A mild and efficient method for preparation of novel 2,2-dichloro-1,3-diarylaziridines from Schiff base compounds in the presence of Ar-cetyl-N,N,N-trimethyl ammonium bromide（CTAB） as phase transfer catalyst has been described.The reaction is dramatically enhanced in the presence of quaternary ammonium salt.The corresponding products have been obtained in excellent yields,high purity and short reaction times.
文摘New quinolone derivatives of 7-[2-aminomethylaziridin-l-yl]quinolone-3-carboxylic acids were synthesized. The structures of these compounds were characterized by IH NMR and HRESI-MS.
基金Supported by the science and technology fund of Wuhan city (No:996 0 0 10 16 G)
文摘(2S, 3R)-2-acetooxymethanyl-3-(P-nitrophenyl)-N-tosylaziridine 5 was synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1, 3-propanediol 1 in four steps with a 24.8% overall yield. This reaction is stereospecific and occurs an expectable configuration inversion at α-carbon atom of benzyl group. The structure of substituted aziridine was determined on FT-IR, NMR, MS and so on.
文摘Macroporous resin （D201）-supported quartemary ammonium bisulfate （D201-HSO4） was prepared and effectively used in catalyzing the hydrolysis of epoxides or aziridines under mild and non-metal conditions to give the corresponding 1,2-diols and β-amino alcohols in high yields. The catalyst was facilely prepared and recyclable.
基金supported by the National Natural Science Foundation of China(No.20872031)
文摘Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri-n-butylphosphane （10 mol%） in the mixture of CH3CN/H20 （10：1）, giving corresponding vicinal diamines in mediate to high yields （58-95%） with good regioselectivitie, while aromatic secondary amine could not react under the same conditions. Tri-n-butylphosphane exhibited different catalytic selectivity to amines from Lewis acid catalysts.
基金Project(50903031) supported by the National Natural Science Foundation of ChinaProject(2009ZM0046) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(N9100240) supported by the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province, China
文摘Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent evaporation method. The results show that,a lower surface free energy with shell polyester is more favourable for the formation of microcapsules. Full encapsulating microcapsules are synthesized with the polyester with a surface free energy of 34.5 mJ/m2. Shell-to-core feeding mass ratio has a significant influence on the morphology and core content of the resulting microcapsules. Well defined spherical microcapsules with uniform shell thickness and core content at around 22% are produced at a shell-to-core mass ratio of 1:1. When 2.5% of colloid stabilizer is used,hollow spherical microcapsules are obtained. A high solvent evaporation rate results in wrinkling and porosity of the microcapsules,and an evaporation rate equivalent to solvent elimination in about 2 h provides a uniform rate of surface hardening. The characterization of the microcapsules by SEM and FTIR demonstrates that polyfunctional aziridine is encapsulated at the centre of the microcapsule. The microcapsules synthesized can be broken at a high shear rate.
文摘A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content of crosslinker in the emulsion, the mechanical properties and solvent resistance of the resin will be apparently improved, but its glass transition temperature (T.) is very low. The lowest amount of crosslinker used in the acrylic resin emulsion is 0.25%. Curing kinetics studied by DSC show that this curing reaction occurs readily because the apparent activation energy of the reaction is low (65.1 kJ/mol). These results demonstrate that the aziridine crosslinker is indeed a low temperature crosslinking agent and can be used at room temperature.
基金Project supported by key subject of Luoyang Normal University (No. 2004yzk90)
文摘A novel compound of chiral 4-hydroxy-4-butyrolactam fused aziridine was synthesized via tandem nucleophilic displacement reaction under mild condition. Its structure was determined by IR, 1H NMR, elemental analysis and X-ray diffraction. The crystal of the new compound is of orthorhombic, space group P212121 with a = 6.4246（6）, b = 13.5081（13）, c = 18.6399（18） A, Mr = 278.39, Z = 4, V = 1617.6（3）A^3, Dc = 1.143 g/cm^3, p（MoKa） = 0.075 mm^-1, F（000） = 608, the final R = 0.0297 and wR = 0.0679.
文摘Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.
基金supported by the National Natural Science Foundation of China(No.21772038)the China Postdoctoral Science Foundation(No.2018M632037)。
文摘A Sc(OTf)3-catalyzed[3+3]cycloaddition of 2,2’-diester aziridines withβ-(indol-2-yl)-α,β-unsaturated ketones was developed,affording polysubstituted tetrahydro-y-carbolines in single diastereoisomers in good to excellent yields.
文摘Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.
基金We thank the National Natural Science Foundation of China (No. 21562037) for financially supporting this work.
文摘Oxidative dehydrogenative [3+3] annulation of benzylhydrazines with N-sulfonylaziridines is described.A series of complex tetrahydro-1,2,4-triazines were produced under mild reaction conditions.
基金supported by the National Natural Science Foundation of China (20672054 & 20872073)the 111 Project of the Ministry of Education of China (B06005)
文摘Basic ion-exchange resins,one kind of polystyryl-supported tertiary amine,were demonstrated to be highly efficient and recyclable catalysts for the fixation of carbon dioxide with aziridines under mild conditions,leading to the formation of 5-aryl-2-oxazolidinone with excellent regio-selectivities.Notably,neither solvents nor any additives were required,and the catalyst could be recovered by simple filtration and directly reused at least five times without significant loss of catalytic activity and selectivity.The present protocol has been applied to reactions of epoxides/propargyl amines with CO_(2)/CS2.This solvent-free process thus represents environmentally friendly catalytic conversion of CO_(2) into value-added chemicals and may have potential in various continuous flow reactors in industry.
基金This work was supported by the Natioanl Natrual Sciencce Foundation of China(21625103,21971125,21801183)China Postdoctoral Science Foundation(2019M660978,2020T130319),and the 111 Project(B12015).
文摘Cycloaddition of CO_(2) with aziridines is an important reaction to obtain high-value products.Porous MOFs can catalyze this reaction,but co-catalysts are still necessary to improve the catalytic performance.Such a reaction catalyzed by MOFs-based materials without co-catalyst has not been reported hitherto.Herein,a porous and stable three-dimensional(3D)framework{[Ni(DCTP)]·6.5DMF}_(n)(1)with a large Langmuir surface area of 3,789 m^(2)/g was synthesized,which displayed high I2 adsorption ability up to 731.0 mg/g and could release it reversibly.Additionally,it exhibited a high CO_(2) adsorption capacity of 104.0 cm^(3)/g at 273 K.The investigation results revealed 1 could effectively catalyze the cycloaddition of CO_(2) and aziridines in the absence of additional co-catalyst,and it could maintain the catalytic activity after five cycles.Furthermore,1 also exhibited high catalytic activity for the gram-scale experiment.Importantly,it is the first MOF material as a heterogeneous catalyst for the conversion of CO_(2) and aziridines without co-catalyst.
