期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
碱催化剂g-C3N4在液相反应中溶胀特性的研究 被引量:2
1
作者 吴结群 华伟明 +1 位作者 乐英红 高滋 《物理化学学报》 SCIE CAS CSCD 北大核心 2020年第1期227-233,共7页
通过三聚氰胺、双腈胺、硫脲或尿素的高温热解制备了四种比表面不同的石墨型碳化氮材料(g-C3N4),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)和N2吸附方法对所得材料进... 通过三聚氰胺、双腈胺、硫脲或尿素的高温热解制备了四种比表面不同的石墨型碳化氮材料(g-C3N4),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)和N2吸附方法对所得材料进行结构与表面性质的表征,用CO2程序升温脱附(CO2-TPD)和酸碱滴定方法测试了其碱性。考察了这些材料对于不同溶剂中苯甲醛与丙二腈Knoevenagel缩合反应的催化活性。g-C3N4在弱极性溶剂甲苯中的催化活性很低,且活性大小与其比表面和表面碱性密切相关,而在极性溶剂乙醇中四种g-C3N4的催化活性则相差不大,且都远高于甲苯中的活性。上述结果无法用常规的碱性表征数据来解释。进一步的实验证明在极性溶剂中g-C3N4会发生溶胀,使得表面暴露更多的碱性位,因而催化活性大大提高。不同溶剂中的反应结果表明g-C3N4的溶胀效应随反应溶剂的极性增加而增强。重复利用实验表明gC3N4在液相反应中具有良好的稳定性,其对于苯甲醛的转化率在重复利用三次后由74.2%下降至63.8%。 展开更多
关键词 g-C3N4 碱催化 KNOEVENAGEL缩合 溶胀效应
下载PDF
Highly selective kinetic resolution of D/L-syn-p-sulfone phenylserine catalyzed by D-threonine aldolase in two-phase ionic solvent
2
作者 Fengfan Liu Zhihao Shi +5 位作者 Jinmei Zhu Xiaobin Liang Mingming Liang Yuanyuan Xie Weike Su jiequn wu 《Green Chemical Engineering》 EI CSCD 2023年第2期212-216,共5页
In the chemical synthesis of L-syn-p-methylsulfoxide phenylserine ethyl ester(D-ethyl ester),L-tartaric acid or enzymatic resolution is employed to resolve the racemate,and thus obtain the target compound,and the rema... In the chemical synthesis of L-syn-p-methylsulfoxide phenylserine ethyl ester(D-ethyl ester),L-tartaric acid or enzymatic resolution is employed to resolve the racemate,and thus obtain the target compound,and the remaining isomer can be recycled to obtain the raw material.In this study,high-purity L-syn-p-methylsulfoxide phenylserine(L-syn-MPS)was obtained.The kinetics of the D-threonine aldolase enzymatic hydrolysis reaction reveals that D-syn-p-sulfoxylphenylserine resolves well in[BMIM][BF 4]ionic solvents.The D/L-syn-MPS racemate was resolved using a two-phase ionic solvent[BMIM][NTf 2]to afford L-syn-MPS(ee(enantiomeric excess)>99%)and a white solid in 41.7%yield.Therefore,this system is suitable for the separation of insoluble aldehydes and successfully avoids the condensation of hydroxyl aldehydes to form D-anti-MPS. 展开更多
关键词 Kinetic resolution Ionic solvent Enzymatic resolution D/L-p-sulphoxyl phenylserine ethyl ester Biphasic reaction system
原文传递
In vitro characterization of a nitro-forming oxygenase involved in 3-(trans-2’-aminocyclopropyl)alanine biosynthesis
3
作者 Linlin Pang Weijing Niu +6 位作者 Yuwei Duan Liujie Huo Aiying Li jiequn wu Youming Zhang Xiaoying Bian Guannan Zhong 《Engineering Microbiology》 2022年第1期35-38,共4页
In vitro characterization experiments revealed the formations of 3-(trans-2’-aminocyclopropyl)alanine((3-Acp)Ala)and 3-(trans-2’-nitrocyclopropyl)alanine((3-Ncp)Ala)are originated via two homologous proteins,BelK an... In vitro characterization experiments revealed the formations of 3-(trans-2’-aminocyclopropyl)alanine((3-Acp)Ala)and 3-(trans-2’-nitrocyclopropyl)alanine((3-Ncp)Ala)are originated via two homologous proteins,BelK and HrmI,which regioselectively catalyze the N𝜀-oxygenation of l-lysine.The two enzymes belong to the emerg-ing heme-oxygenase-like diiron oxidase and oxygenase(HDO)superfamily and the catalytic center of BelK is validated by homology modeling and site-directed mutations.Based on the in vitro characterization,the biosyn-thetic pathways of(3-Acp)Ala and(3-Ncp)Ala are proposed. 展开更多
关键词 Nitro-forming oxygenase HDO superfamily protein Belactosin A Hormaomycin Cyclopropyl ring
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部