A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the aci...A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.展开更多
Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were develop...Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.展开更多
A novel aliphatic sulfonie acid ion exchange resin was prepared from ethylenediamined polystyrene(PS-acyl-EDA),2-acrylamido-2-methylproanesulfonic acid(AMPS)by Michael reaction.This kind of resin has a longer chain th...A novel aliphatic sulfonie acid ion exchange resin was prepared from ethylenediamined polystyrene(PS-acyl-EDA),2-acrylamido-2-methylproanesulfonic acid(AMPS)by Michael reaction.This kind of resin has a longer chain than conventional sulphonic polystyrene resin,that is,the former is easier to react with other compound.The effect of the reaction time,reaction temperature,catalyst amount,reagent amount and the charge ration on reaction result were discussed.Under the optimum condition,the maximum loading of the sulfonie acid ion exchange resin could be up to 1.15 mmol·g-1 resin.The product was characterized with FT-IR.The filling material of chromatographic column could be prepared by this method.展开更多
Different Michael addition reactions catalyzed by solid base K2O/γ-Al2O3 and KF/γ-Al2O3,MgO/γ-Al2O3 prepared by microwave irradiation method were reported in this paper.For the K2O/γ-Al2O3,not only good yield was ...Different Michael addition reactions catalyzed by solid base K2O/γ-Al2O3 and KF/γ-Al2O3,MgO/γ-Al2O3 prepared by microwave irradiation method were reported in this paper.For the K2O/γ-Al2O3,not only good yield was attained but also made the reaction of Acetonitrile that usually is regarded as inactive carbonion and α,β-unsaturated compound to carry out.The yield of Michael reaction of Ethyl acetoacetate and Crotonaldehyde catalyzed by KF/γ-Al2O3,MgO/γ-Al2O3,MgO/NaY all could reach to 80% and the latter could reach to 90%.At the same time,the catalysts of different content（the ratio of load）of MgO were also applied in this reaction,and it was found that the best content of MgO was 20%～25%.展开更多
文摘A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.
基金funded by the Latvian State Institute of Wood Chemistry Bioeconomic grant no.04-24“Development of Composites from Polymer Resin Synthesized from Tall Oil Fatty Acids and Reinforced with Various Fillers”(FiTeCo).
文摘Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.
文摘A novel aliphatic sulfonie acid ion exchange resin was prepared from ethylenediamined polystyrene(PS-acyl-EDA),2-acrylamido-2-methylproanesulfonic acid(AMPS)by Michael reaction.This kind of resin has a longer chain than conventional sulphonic polystyrene resin,that is,the former is easier to react with other compound.The effect of the reaction time,reaction temperature,catalyst amount,reagent amount and the charge ration on reaction result were discussed.Under the optimum condition,the maximum loading of the sulfonie acid ion exchange resin could be up to 1.15 mmol·g-1 resin.The product was characterized with FT-IR.The filling material of chromatographic column could be prepared by this method.
文摘Different Michael addition reactions catalyzed by solid base K2O/γ-Al2O3 and KF/γ-Al2O3,MgO/γ-Al2O3 prepared by microwave irradiation method were reported in this paper.For the K2O/γ-Al2O3,not only good yield was attained but also made the reaction of Acetonitrile that usually is regarded as inactive carbonion and α,β-unsaturated compound to carry out.The yield of Michael reaction of Ethyl acetoacetate and Crotonaldehyde catalyzed by KF/γ-Al2O3,MgO/γ-Al2O3,MgO/NaY all could reach to 80% and the latter could reach to 90%.At the same time,the catalysts of different content（the ratio of load）of MgO were also applied in this reaction,and it was found that the best content of MgO was 20%～25%.
