SAPO-34 was synthesized with n-butylamine（BA） as a template for the first time.Crystallization temperature and initial Si amount were important factors leading to successful syntheses.Lamellar AlPO-kanemite tends to...SAPO-34 was synthesized with n-butylamine（BA） as a template for the first time.Crystallization temperature and initial Si amount were important factors leading to successful syntheses.Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures,though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature.Higher temperature（240℃） can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation.The crystallization processes at 200 and 240℃ were investigated and compared.We used the aminothermal method to synthesize SAPO-34-BA at 240℃ and also found n-propylamine is a suitable template for the synthesis of SAPO-34.The SAPO-34-BA products were characterized by many techniques.SAPO-34-BA has good thermal stability,crystallinity and porosity.BA remained intact in the crystals with ~1.8 BA molecule per chabazite cage.The catalytic performance of SAPO-34 was tested in the methanol amination reaction,which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated,suggesting that this material is a good candidate for the synthesis of methylamines.展开更多
Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a ph...Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.展开更多
The efficient synthesis of dimethylhexane-1,6-dicarbamate(HDC)from 1,6-hexanediamine(HDA)and methyl carbonate over a series of heterogeneous catalysts(e.g.,Mg O,Fe2O3,Mo2O3,and Ce O2)was investigated.The reaction path...The efficient synthesis of dimethylhexane-1,6-dicarbamate(HDC)from 1,6-hexanediamine(HDA)and methyl carbonate over a series of heterogeneous catalysts(e.g.,Mg O,Fe2O3,Mo2O3,and Ce O2)was investigated.The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments.Under optimized conditions,100%HDA conversion with 83.1%HDCtotaland 16.9%polyurea was obtained using a onestep with high temperature procedure with Ce O2as the catalyst.A new two-step with variable temperature technology was developed based on the reaction pathway to reduce the polyurea yield.Using the proposed method,the HDCtotalyield reached 95.2%,whereas the polyurea yield decreased to 4.8%.The Ce O2catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods.展开更多
基金supported by the National Natural Science Foundation of China(21676262,21476228,21506207)the Key Research Program of Frontier Sciences of CAS(QYZDB-SSW-JSC040)~~
文摘SAPO-34 was synthesized with n-butylamine（BA） as a template for the first time.Crystallization temperature and initial Si amount were important factors leading to successful syntheses.Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures,though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature.Higher temperature（240℃） can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation.The crystallization processes at 200 and 240℃ were investigated and compared.We used the aminothermal method to synthesize SAPO-34-BA at 240℃ and also found n-propylamine is a suitable template for the synthesis of SAPO-34.The SAPO-34-BA products were characterized by many techniques.SAPO-34-BA has good thermal stability,crystallinity and porosity.BA remained intact in the crystals with ~1.8 BA molecule per chabazite cage.The catalytic performance of SAPO-34 was tested in the methanol amination reaction,which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated,suggesting that this material is a good candidate for the synthesis of methylamines.
文摘Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.
基金Supported by the Science and Technology Ministry of China(2013BAC11B03)National Nature Science Foundation of China(21476244,21206180,21406245)
文摘The efficient synthesis of dimethylhexane-1,6-dicarbamate(HDC)from 1,6-hexanediamine(HDA)and methyl carbonate over a series of heterogeneous catalysts(e.g.,Mg O,Fe2O3,Mo2O3,and Ce O2)was investigated.The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments.Under optimized conditions,100%HDA conversion with 83.1%HDCtotaland 16.9%polyurea was obtained using a onestep with high temperature procedure with Ce O2as the catalyst.A new two-step with variable temperature technology was developed based on the reaction pathway to reduce the polyurea yield.Using the proposed method,the HDCtotalyield reached 95.2%,whereas the polyurea yield decreased to 4.8%.The Ce O2catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods.
