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。     

氧化石墨烯/硫杂杯芳烃复合材料富集分离-石墨炉原子吸收法测定痕量铊

自制了一种新型氧化石墨烯/硫杂杯芳烃复合材料,用扫描电镜、红外光谱、元素分析、热分析对合成产品进行表征,用于痕量铊的富集,提出了氧化石墨烯/硫杂杯芳烃复合材料分离预富集,石墨炉原子吸收光谱法测定痕量铊的一种新方法,探讨了溶液pH值、温度、洗脱条件及干扰离子对痕量铊分离富集的影响,结果发现该材料对Tl3+具有较大吸附量。在pH 8.0,温度为(23±1)℃条件下,铊可被该材料定量吸附,其吸附容量为73.1 mg/g。吸附的铊可被5.0 mL酸性硫脲(0.5 mol/L HCl+1.0 mol/L硫脲)完全洗脱,方法的线性范围为0.012~15μg/L,检出限(3σ)为0.008μg/L,对0.50μg/L Tl3+工作液测定的RSD(n=7)为2.3%,加标回收率为93.6%~104.1%。此法用于生物样品和环境水样中痕量铊的测定,结果满意。     

固载硫杂杯芳烃树脂分离富集-火焰原子吸收法测定痕置银

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／L HCl＋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。     

交联壳聚糖分离富集-火焰原子吸收法测定水样中痕量银

以甲醛、环硫氯丙烷为交联剂,由壳聚糖合成了一种新型的交联壳聚糖微球(FCCIS)分离树脂,研究了不同条件下FCCTS对Ag(Ⅰ)的吸附性能.在pH 3.6时FCCTS对Ag(Ⅰ)定量吸附,吸附在树脂上的Ag(Ⅰ)可用0.5 moL/L的氨水将其洗脱,用火焰原子吸收光谱测定.该法对Ag(Ⅰ)的检出限为61 ng/mL(3σ,n=8),相对标准偏差为2.2%(n=7,ρ=2μg/mL),线性范围为0.05～4μg/mL,加标回收率在98.8%～101.7%之间.该法已用于水样中痕量银测定.     

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。     

磺化硫杂杯[4]芳烃修饰纳米金的制备及对水溶液中Cr3+的比色检测

在不需外加还原剂的条件下一步原位合成了磺化硫杂杯[4]芳烃修饰的纳米金,并将其作为比色探针对金属离子进行检测。研究表明,磺化硫杂杯[4]芳烃修饰的纳米金能够选择性的识别CrP3+P,其检测限可达到1μM。     

抑制褪色光度法测定油炸面制食品中痕量铝

建立抑制褪色光度法快速测定食品中痕量铝的方法。在硫酸介质中,一定量的铝离子对溴酸钾氧化罗丹明B褪色有抑制作用,据此建立了抑制褪色光度法快速测定食品中痕量铝的新体系,最大吸收波长为550 nm。在1 mol/L硫酸介质中,铝含量在0.07~0.4μg/mL范围内与吸光度具有良好的线性关系,相关系数r=0.9995,检出限为0.02μg/mL。用该方法测定油炸面制食品中痕量铝,测定结果的相对标准偏差为1.3%~3.1%(n=11),加标回收率为99.3%~103.5%。该方法测定结果准确可靠,可用于食品中痕量铝的测定。     

电感耦合等离子体原子发射光谱法测定盐酸多巴酚丁胺注射液中硫

采用电感耦合等离子体原子发射光谱法测定注射液中硫元素含量。样品经高压消解处理，并加入体积分数5%的硝酸溶液，使样品中的硫元素氧化为稳定的硫酸根离子，使用电感耦合全谱等离子体发射光谱仪，在180.731nm处测量硫的发射光谱，计算硫元素的质量浓度。硫元素的质量浓度在0～10μg/mL范围内与其对应的发射强度线性相关，线性回归方程为y=54.887x+2.208 6，相关系数0.999 9，方法的检出限为0.007μg/mL，对理论硫元素质量浓度为74.1 mg/L的盐酸多巴酚丁胺注射液加标试验，测定值的相对标准偏差为2.23%(n=7)，加标回收率为103.5%～106.2%。     

选择性合成三取代乙氧羰基甲氧基硫杂杯[4]芳烃

对叔丁基硫杂杯[4]芳烃与氯乙酸乙酯在K2CO3/丙酮体系中反应,选择性地合成了三取代乙氧羰基甲氧基硫杂杯[4]芳烃,产率78%,其结构经1H NMR,MS和元素分析表征.     

浊点萃取电热原子吸收光谱法测定水中痕量铊

采用吡咯烷基二硫代氨基甲酸铵(APDC)为螯合剂,Triton X-114作为表面活性剂,建立了浊点萃取预富集电热原子吸收光谱法测定水中痕量铊的方法。在优化的实验条件下,方法的检出限可达0.07μg/L,相对标准偏差为3.6%(4μg/L,n=7),加标回收率为93%~106%,富集倍率为31。该方法成功应用于自来水和河水中痕量铊的测定。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.