三乙烯四胺修饰交联壳聚糖树脂的制备及其对痕量镉的吸附性能研究

以戊二醛、环氧氯丙烷为交联剂,用三乙烯四胺改性,由壳聚糖合成了一种新型的三乙烯四胺修饰交联壳聚糖微球(CRN)分离树脂,研究了不同条件下CRN对Cd2+的吸附性能。在pH6.0时,CRN能定量吸附溶液中的痕量Cd2+,其静态饱和吸附容量为31.0 mg/g。吸附在CRN上的Cd2+可用0.5 mol/L的H2SO4洗脱,用火焰原子吸收法测定洗脱液中Cd2+的含量。本法对Cd2+的检出限(3σ)为24.6 ng/mL,相对标准偏差(RSD)为2.1%(n=11,c=1.0μg/mL),加标回收率在97.3%～104.0%。该方法可用于矿渣中痕量镉的测定。     

罗丹宁-壳聚糖固相萃取-原子吸收光谱法测定环境水样中痕量银

本文采用化学修饰技术制备了新型固相萃取材料罗丹宁-壳聚糖,用傅立叶红外(IR)光谱对其进行了表征。以该材料作为固相萃取剂,采用火焰原子吸收(FAAS)法为检测手段,在动态条件下系统研究了该吸附材料对痕量Ag+的吸附性能。研究结果表明:在pH=5.0,室温下以1.8mL/min速度流过分离柱,试液中的Ag+能被该材料定量吸附,其动态饱和吸附容量为72.62mg/g。吸附的Ag+可用8mL 0.1mol/L硫脲-0.05 mol/L HNO3混合液以0.7 mL/min流速完全洗脱,洗脱液中的Ag+用FAAS法测定。该方法对Ag+的检出限(3σ,n=11)为8.50μg/L,线性范围为0.01~5.0mg/L,相对标准偏差(RSD)为0.72%;加标回收率在97.8%~102.7%之间。方法用于实际环境水样中痕量Ag+的测定,结果满意。     

负载硫杂杯芳烃树脂微柱分离富集-火焰原子吸收法测定痕量金

建立了大孔径树脂D101负载硫杂杯芳烃树脂微柱分离富集-火焰原子吸收光谱法测定痕量金的新方法。探讨了负载硫杂杯芳烃树脂对金的吸附原理与最佳条件。该法对金的检出限为0.23 ng/mL(3σ,n=11),线性范围为0.01~1μg/mL。对0.2μg/mL的Au 标液进行5次测定,RSD=2.1%,加标回收率在98.4%~103.3%之间。方法用于矿渣样中痕量金的分析。     

高效液相色谱化学发光检测法测定食品中苏丹红Ⅰ

基于碱性条件下,苏丹红Ⅰ对鲁米诺-KIO4发光体系的增敏作用,建立了高效液相色谱化学发光测定苏丹红Ⅰ的新方法。方法采用Phenomenex C18色谱柱(250×4.6mm,5μm),以乙腈∶甲醇∶水=5∶4∶1(V/V/V)为流动相,在0.001～0.50μg/mL范围内,苏丹红Ⅰ浓度与发光强度呈良好的线性关系,相关系数为0.9996,检出限为5ng/kg,相对标准偏差为1.45%(c=0.01μg/mL,n=6),加标回收率为95.0%～104.0%。该法灵敏、准确,用于实际样品中苏丹红Ⅰ的测定,结果令人满意。     

中孔分子筛Ti-MCM-48的合成及其对痕量银(Ⅰ)的吸附性能研究与应用

以正硅酸乙酯、钛酸丁酯为原料,十六烷基三甲基溴化铵为表面活性剂合成中孔分子筛Ti-MCM-48。研究了中孔分子筛Ti-MCM-48分离富集材料对银(Ⅰ)的吸附性能,优化了影响其吸附和解吸的主要条件。结果表明,在pH=3.0的柠檬酸-柠檬酸钠缓冲溶液中,恒温35℃振荡25min时,银(Ⅰ)能被该材料吸附完全,其静态饱和吸附容量为2.96mg/g。吸附在中孔分子筛Ti-MCM-48上的银(Ⅰ)可用5mL 0.5mol/L HNO3-0.1mol/L硫脲洗脱液完全洗脱。采用火焰原子吸收光谱法(FAAS)测定洗脱液中银(Ⅰ)的方法检出限(3σ)为21.39ng/mL,线性范围为0.02～5.0μg/mL(r=0.9995),相对标准偏差(RSD)为1.25%,加标回收率在96%～102%之间。方法可用于实际样品中痕量银的测定。     

固载硫杂杯芳烃树脂分离富集-火焰原子吸收法测定痕量银

报道了色谱301固载硫杂杯芳烃树脂分离预富集-火焰原子吸收光谱法测定痕量银的新方法。探讨了固载硫杂杯芳烃树脂对银的吸附原理与最佳条件。将含Ag 试液在pH=10、温度为23±2℃的条件下恒温震荡10min,静置10min,Ag 可被树脂定量富集被吸附的Ag 可用5mL酸性硫脲(0.15mol/LHCl 0.15mol/L硫脲)完全洗脱,洗脱液中的银用火焰原子吸收光谱法测定。该法对银的检出限为0.17μg/L(3σ,n=11);线性范围为0.006~3mg/L。对0.18mg/L的Ag 标液进行7次测定,RSD=1.53%,回收率在99.9%~105.0%之间。用于“二次资源”锌矿渣和环境水样中痕量银的测定,结果满意。     

硅胶负载碳纳米管分离富集水中痕量银

以NaOH为沉淀试剂,将水样中的Ag+在线生成Ag2O沉淀,并即时被滞留在硅胶负载的碳纳米管表面。被吸附的Ag2O沉淀用HNO3(10%,V/V)洗脱,并用火焰原子吸收法检测。当进样体积为5.4mL时,线性范围为1～120μg/L,富集系数为34.5;检出限为0.35μg/L;相对标准偏差为0.5%(40μg/L,n=7),采样频率为47次/h。结果表明:本方法的富集系数、检出限及精密度均明显优于以纯碳纳米管和纯硅胶微珠为吸附剂收集Ag2O的体系。将此系统应用于实际水样中银的测定,加标回收率在96%～108%之间。     

交联壳聚糖预富集分离-石墨炉原子吸收光谱法测定痕量银(Ⅰ)

研究了交联壳聚糖(CCTS)对银(Ⅰ)的吸附性能,提出了用CCTS作为富集剂预富集分离水样中痕量银的新方法。研究结果表明:在pH 3.0时,CCTS对银的吸附率达99%以上,其饱和吸附量为0.6 mg/g;采用8 mL 0.5 moL/L的氨水可将吸附在CCTS上的银定量洗脱。用CCTS将水中痕量银(Ⅰ)富集20倍,石墨炉原子吸收光谱法(GFAAS)进行检测,检出限(3σ,n=6)为0.406μg/L,相对标准偏差(RSD)小于6.8%。该方法也适合贵金属银的回收利用。     

三聚氰胺-甲醛-三乙烯四胺树脂的合成及其对痕量银的吸附性能研究与应用

以甲醛为交联剂,以三聚氰胺、三乙烯四胺为原料合成了一种新型的三聚氰胺-甲醛-三乙烯四胺(MF-TETA)分离树脂,研究了MF-TETA分离树脂对痕量银的分离富集性能,探讨了MF-TETA分离树脂对银的吸附原理与最佳条件。在pH6.0、温度为35℃的条件下,试液中的银可被MF-TETA树脂定量吸附,其静态饱和吸附容量为32 mg/g,吸附在树脂上的银可用10 mL0.05 mol/L HNO3完全洗脱,洗脱液中的银用火焰原子吸收光谱法(FAAS)测定。该法对银的检出限为16 ng/mL(3σ,n=11),线性范围为0.05~5mg/mL,RSD=2.2%,回收率在95.8%~102.0%之间,方法可用于中草药中痕量银的测定。     

离子印迹壳聚糖/凹土分离富集-火焰原子吸收光谱测定中药材中痕量Cd(Ⅱ)的研究

建立了离子印迹壳聚糖/凹凸棒石(IICA)分离富集-火焰原子吸收光谱(FAAS)测定中药材中痕量Cd(Ⅱ)的新方法。在动态吸附条件下,系统研究了溶液pH值、流速、洗脱条件和干扰离子对痕量Cd(Ⅱ)分离富集的影响。研究表明,在pH为4.5,上样流速为0.60mL/min条件下,Cd(Ⅱ)能被IICA定量富集;吸附的Cd(Ⅱ)可用1.0mol/L HCl-0.1mol/L甲基异丁酮的乙醇溶液,在流速为0.96mL/min条件下完全洗脱。优化条件下,IICA对Cd(Ⅱ)的动态吸附容量为56.45mg/g。线性范围为0.00097～1.28mg/L,r=0.9994,检出限(3σ,n=11)为0.97μg/L,相对标准偏差为1.32%(n=6,c=0.08mg/L),回收率在96.5%～106.4%之间。该方法操作简便,灵敏度和精密度高,可应用于实际中药材样品中痕量镉的测定。     

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.