西索米星在大孔弱酸树脂上的吸附研究与传质系数的测定

对西索米星在大孔弱酸树脂上吸附平衡与动力学进行研究。建立了间歇吸附表面有效扩散模型,利用实验测定了吸附平衡曲线和吸附速率曲线,结合正交配置法、遗传算法直接拟合出固相粒内表面有效扩散系数Dc和液相传质系数kf,其拟合均方根误差不大于0.025。研究结果表明,西索米星在D113树脂上的吸附平衡符合Langmiur方程,吸附速率实验数据与吸附模型数值解拟合良好,表面有效扩散模型能够很好地描述西索米星在弱酸树脂D113上的吸附行为。在实验条件下,表面有效扩散系数Dc约为2.00×10-8～4.09×10-8cm2/s,液相传质系数kf约为9.00×10-5～2.95×10-4cm/s。     

西索米星在大孔弱酸树脂上的吸附研究与传质系数的测定

对西索米星在大孔弱酸树脂上吸附平衡与动力学进行研究。建立了间歇吸附表面有效扩散模型,利用实验测定了吸附平衡曲线和吸附速率曲线,结合正交配置法、遗传算法直接拟合出固相粒内表面有效扩散系数Dc和液相传质系数kf,其拟合均方根误差不大于0.025。研究结果表明,西索米星在D113树脂上的吸附平衡符合Langmiur方程,吸附速率实验数据与吸附模型数值解拟合良好,表面有效扩散模型能够很好地描述西索米星在弱酸树脂D113上的吸附行为。在实验条件下,表面有效扩散系数Dc约为2.00×10-8~4.09×10-8cm2/s,液相传质系数kf约为9.00×10-5~2.95×10-4cm/s。     

离子交换树脂吸附胞嘧啶核苷三磷酸的动力学和热力学研究

根据CTP在离子交换树脂上的吸附容量和分离因数的大小,确定Duolite A-30树脂适合CTP与CDP及CMP之间的分离.CTP在Duolite A-30树脂上的吸附动力学和热力学研究表明,在283.15～303.15K之间,CTP的质量浓度在7.5g/L以上时,Duolite A-30树脂对CTP的吸附主要受颗粒扩散的控制,其有效扩散系数为D=3.47×10-7cm2/s,溶液的质量浓度≤1.0g/L时,CTP与Duolitc A-30树脂之间的交换速率主要受液膜控制,其液膜扩散系数为Kf=4.112×10-4/s.热力学参数Eα=9.008kJ/mol,△H=5.17kJ/mol·K,△S283.15K=80.28J/mol·K.     

三磷酸胞苷在Duolite A-30树脂上的交换过程研究

根据CTP在离子交换树脂上的吸附容量和分离因数的大小,确定Duolite A-30树脂适合CTP与CDP,CMP之间的分离.对CTP在Duolite A-30树脂上的吸附动力学和热力学研究表明,在283.15K~303.15K之间,CTP的质量浓度在7.5g/L以上时,Duolite A-30树脂对CTP的吸附主要受颗粒扩散的控制,其有效扩散系数为D=3.47×10-7cm2/s,溶液的质量浓度≤1.0g/L时,CTP与Duolite A-30树脂之间的交换速率主要受液膜控制,其液膜扩散系数为Kf =4.112×10-4/s.同时测定了不同条件下三磷酸胞苷溶液在Duolite A-30树脂固定床离子交换柱中的穿透曲线,研究了进口浓度、进口流速、原料液温度、原料液的pH值及柱高对穿透曲线的影响.用二阶动力学推动力模型描述固定床动态过程,考察了轴向返混对穿透曲线的影响,并从穿透曲线回归得到总传质系数,模型计算值与实验数据符合良好.     

S-腺苷-L-蛋氨酸在弱酸树脂D113上的离子交换动力学研究

考察了S-腺苷-L-蛋氨酸在弱酸树脂D113上的离子交换动力学.根据扩散控制模型,利用Fick定律关联计算得到有效内扩散系数D(数量级约为10-8cm2/s～10-9cm2/s)以及两相分配因子K,两者受浓度影响较大;进一步实验表明,较低的进样速度和较高的样品浓度利于提高分离得率和效率,是影响其分离的关键因素.     

DuoliteA-30树脂对5’-三磷酸尿苷的静态吸附热力学及动力学特征

研究了DuoloyeA-30树脂对水溶液中5'-三磷酸尿苷(UTP)的静态吸附热力学和动力学特征,测定了不同温度下吸附等温线热力学性能的变化,利用热力学函数关系计算了吸附焓、自由能和吸附熵,确定在实验范围内,DuoliteA-30树脂对UTP的吸附符合Langmuir吸附等温式,吸附过程为自发的吸热过程.考察了温度、浓度、粒径、溶液pH值和搅拌速度对交换过程的影响,运用动边界模型(MBM)描述交换过程的动力学,确定在实验范围内离子交换行为的速度控制步骤为颗粒扩散,并推算出了交换过程的表观活化能,反应级数以及速率常数,得到了UTP在DuoliteA-30树脂上的动力学总方程.     

氨基酸螯合吸附树脂对苯酚的吸附行为研究

合成了一种L-酪氨酸修饰的螯合吸附树脂(AJS-02),并与超高交联树脂NDA-150作对比,研究了其对苯酚的吸附和脱附行为.静态实验结果表明,在研究的浓度范围内,吸附平衡数据符合Langmuir等温吸附方程且吸附为放热过程.溶液的初始浓度为100 mg/L、吸附温度为288 K时,苯酚在AJS-02和NDA-150上的平衡吸附量分别为76.98和91.97 mg/g,苯酚在两种树脂上的吸附是比表面积和表面官能团共同作用的结果.动力学数据表明吸附动力学符合液膜扩散方程和颗粒内扩散方程,液膜扩散为吸附速率的主要控制步骤.动态吸附-脱附实验表明,AJS-02树脂对苯酚的动态穿透吸附量和饱和吸附量分别为5.26×10-2和6.60×10-2mmol/mL,采用95%乙醇作脱附剂,脱附率可达91.5%以上.     

氨基修饰聚苯乙烯树脂对酚酸物质的吸附性能

通过对XAD 4聚苯乙烯树脂的氨基修饰制备了一种亲水性的NDA 10 0树脂 .研究了NDA 10 0树脂对苯酚和对羟基苯甲酸等酚酸类物质的吸附动力学和热力学行为 .结果表明 ,NDA 10 0树脂对苯酚和对羟基苯甲酸具有良好的吸附性能 ,在研究的浓度范围内 ,吸附平衡数据符合Langmuir和Freundlich等温吸附方程 ,吸附为放热的物理吸附过程 .吸附动力学符合Lagergren准二级速率方程 ,颗粒内扩散为吸附速率的主要控制步骤 .     

氮化硼对模拟放射性废水中Mn~(2+)的吸附特征

以氮化硼为吸附剂,考察其对模拟放射性废水中锰的吸附平衡、吸附动力学及热力学特征。表征结果显示,氮化硼为纤维状材料,直径在1~2μm,长度在10~20μm,表面多孔,并且包含羟基、氨基等基团。实验结果表明,当废水中Mn2+浓度为11mg/L,氮化硼投加量为0.5g/L时,5min即可达到吸附平衡,平衡时吸附量为10.93mg/g。氮化硼对Mn2+的吸附符合Freundlich、Langmuir及D-R吸附等温模型,吸附机理主要为离子交换。吸附过程可用拟二级动力学模型描述,该过程分为两个阶段,第1阶段中颗粒内扩散为吸附的主要限速步骤,第2阶段主要受液膜扩散作用控制。该过程是自发进行的吸热反应,升高温度有利于反应的发生。     

转型TP207树脂从低浓度稀土溶液中富集稀土的研究

为实现从低浓度稀土溶液中高效富集稀土,通过动态吸附-解吸试验,研究了转型TP207树脂吸附稀土的规律。系统考察了离子交换线速度、吸附液体积、初始p H值、铝离子对树脂吸附稀土容量的影响,以及解吸液体积对稀土解吸率的影响。结果表明：在稀土浓度为1.65g·L^-1,离子交换线速度为3 cm·min^-1,吸附液体积为7.50 L,初始p H值为3.46的条件下,TP207树脂对稀土吸附量Q_n1=0.18 g·g^-1;稀土溶液中铝和稀土存在竞争吸附,当Al³⁺浓度为0.35 g·L^-1时,TP207树脂对稀土吸附量Q_n2降为0.11 g·g^-1;采用5%的稀HCl对饱和树脂进行解吸,在解吸液体积为0.525 L时,稀土解吸率可达99.45%;树脂吸附稀土过程属于阳离子交换反应,符合Langmuir等温吸附模型,为单分子层吸附,树脂中C=O的O原子和C-N的N原子均参与配位反应。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.