The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/A...The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/Al2O3 ratios of 25 and 75.In order to affect the strength and distribution of the acidic sites, as well as the mobility of NH4^+ ions in the zeolites cages, a secondary level of porosity was introduced in the NH4^+-Beta, presenting a different stability versus alkaline treatment, by using a thermal or an ultrasound assisted method.By analyzing the catalytic behavior in these two series of samples with respect to the changes in porosity by nonlocal density functional theory, structure by XRD, amount of acid sites by FT-IR and mobility of NH4^+ cations by measurements of reversible NH4^+ exchange capacity, was evidenced a decrease in catalytic performances both in terms of rate of HMF depletion and productivity to the main products, when confinement of the ammonium ions is lost due to the introduction of mesoporosity.The high capability of ammonium ions release, associated to the mono-dentate configuration,and the minor confinement effect inside the zeolite pore system, due to the more opened pores structure of mesoporous zeolites, hinders both the direct etherification of HMF to EMF [5-(ethoxymethyl)furan-2-carbaldehyde] and the parallel reaction pathway via acetalization, favoring the rapid desorption of the HMFDEA [5-(hydroxymethyl)furfural diethyl acetal] product out of the crystal and the consequent inhibition of the consecutive reactions to EMFDEA [5-(ethoxymethyl)furfural diethyl acetal] and EMF.展开更多
In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural（EMF）, 2,5-（bis（ethoxymethyl）furan（BEMF） and ethyl levulinate（EL）, was performed in an in-s...In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural（EMF）, 2,5-（bis（ethoxymethyl）furan（BEMF） and ethyl levulinate（EL）, was performed in an in-situ generated catalyst system through consecutive dehydration, etherification, and transfer hydrogenation. Specifically, ZrOCl2·8H2O was in-situ decomposed into HCl and ZrO（OH）2 in ethanol, which effectively catalyzed the dehydration/etherification of fructose to 5-ethoxymethylfurfural（EMF） and subsequent reductive etherification of EMF using ethanol as H-donor, respectively. EMF, BEMF and EL were detected as the main products, and total yield of detectable products of up to 65.4% was obtained at 200 ℃ in only 2 h.展开更多
目的:探究影响人类免疫缺陷病毒Ⅰ型(human immunodeficiency virus type 1,HIV-1)非核苷类逆转录酶抑制剂6-苄基-1-乙氧甲基-5-异丙基尿嘧啶[6-benzyl-1-(ethoxymethyl)-5-isopropyluracil,MKC-442]及其类似物抗病毒活性的主要分子微...目的:探究影响人类免疫缺陷病毒Ⅰ型(human immunodeficiency virus type 1,HIV-1)非核苷类逆转录酶抑制剂6-苄基-1-乙氧甲基-5-异丙基尿嘧啶[6-benzyl-1-(ethoxymethyl)-5-isopropyluracil,MKC-442]及其类似物抗病毒活性的主要分子微观结构因素。方法:针对45个MKC-442及其类似物,利用遗传函数逼近法(genetic function approximation,GFA)构建10个抗HIV-1活性与优选的分子结构描述符之间的二维定量构效关系(2-dimensional quantitative structure-activity relationship,2D-QSAR)模型,从中挑选出最优模型并对其进行验证,据此阐明影响MKC-442及其类似物抗HIV-1活性的主要微观结构因素。结果:最优2D-QSAR模型的非交叉验证相关系数r2为0.7845,交叉验证相关系数q2为0.6958,预测验证相关系数r2pred为0.8415,表明其具有较高的预测能力和稳定性。结论:研究表明,MKC-442及其类似物抗HIV-1活性主要与描述符JursFNSA2,ShadowYZ,DipoleX,Kappa3AM和CHIV3P相关,为MKC-442及其类似物的进一步结构修饰打下了一定的理论基础。展开更多
文摘The role of NH4^+ ion confinement in the catalytic etherification of HMF(5-hydroxymethylfurfural) with ethanol to biodiesel additives was evidenced by studying the catalytic behavior of NH4^+-Beta zeolites with SiO2/Al2O3 ratios of 25 and 75.In order to affect the strength and distribution of the acidic sites, as well as the mobility of NH4^+ ions in the zeolites cages, a secondary level of porosity was introduced in the NH4^+-Beta, presenting a different stability versus alkaline treatment, by using a thermal or an ultrasound assisted method.By analyzing the catalytic behavior in these two series of samples with respect to the changes in porosity by nonlocal density functional theory, structure by XRD, amount of acid sites by FT-IR and mobility of NH4^+ cations by measurements of reversible NH4^+ exchange capacity, was evidenced a decrease in catalytic performances both in terms of rate of HMF depletion and productivity to the main products, when confinement of the ammonium ions is lost due to the introduction of mesoporosity.The high capability of ammonium ions release, associated to the mono-dentate configuration,and the minor confinement effect inside the zeolite pore system, due to the more opened pores structure of mesoporous zeolites, hinders both the direct etherification of HMF to EMF [5-(ethoxymethyl)furan-2-carbaldehyde] and the parallel reaction pathway via acetalization, favoring the rapid desorption of the HMFDEA [5-(hydroxymethyl)furfural diethyl acetal] product out of the crystal and the consequent inhibition of the consecutive reactions to EMFDEA [5-(ethoxymethyl)furfural diethyl acetal] and EMF.
基金financial support from the National Natural Science Foundation of China (Grant Nos.21706223 21776234+7 种基金 21676223 21506177)the Fundamental Research Funds for the Central Universities (Grant Nos. 20720160087 20720160077)the Natural Science Foundation of Fujian Province of China (Grant Nos. 2016J01077 2015J05034 2014J01209)the Education Department of Fujian Province (Grant No. JZ160398)
文摘In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural（EMF）, 2,5-（bis（ethoxymethyl）furan（BEMF） and ethyl levulinate（EL）, was performed in an in-situ generated catalyst system through consecutive dehydration, etherification, and transfer hydrogenation. Specifically, ZrOCl2·8H2O was in-situ decomposed into HCl and ZrO（OH）2 in ethanol, which effectively catalyzed the dehydration/etherification of fructose to 5-ethoxymethylfurfural（EMF） and subsequent reductive etherification of EMF using ethanol as H-donor, respectively. EMF, BEMF and EL were detected as the main products, and total yield of detectable products of up to 65.4% was obtained at 200 ℃ in only 2 h.
文摘目的:探究影响人类免疫缺陷病毒Ⅰ型(human immunodeficiency virus type 1,HIV-1)非核苷类逆转录酶抑制剂6-苄基-1-乙氧甲基-5-异丙基尿嘧啶[6-benzyl-1-(ethoxymethyl)-5-isopropyluracil,MKC-442]及其类似物抗病毒活性的主要分子微观结构因素。方法:针对45个MKC-442及其类似物,利用遗传函数逼近法(genetic function approximation,GFA)构建10个抗HIV-1活性与优选的分子结构描述符之间的二维定量构效关系(2-dimensional quantitative structure-activity relationship,2D-QSAR)模型,从中挑选出最优模型并对其进行验证,据此阐明影响MKC-442及其类似物抗HIV-1活性的主要微观结构因素。结果:最优2D-QSAR模型的非交叉验证相关系数r2为0.7845,交叉验证相关系数q2为0.6958,预测验证相关系数r2pred为0.8415,表明其具有较高的预测能力和稳定性。结论:研究表明,MKC-442及其类似物抗HIV-1活性主要与描述符JursFNSA2,ShadowYZ,DipoleX,Kappa3AM和CHIV3P相关,为MKC-442及其类似物的进一步结构修饰打下了一定的理论基础。
