镍(Ⅱ)-1-(1吡啶偶氮)-2-萘酚-十二烷基苯磺酸钠体系共振光散射法测定痕量镍

在pH 8.0的Tris-盐酸缓冲介质中,利用十二烷基苯磺酸钠(SDBS)增敏镍(Ⅱ)和1-(2-吡啶偶氮)-2-萘酚(PAN)形成离子缔合物体系,使体系共振光散射增强.体系最大散射波长545 nm,在15～500μg·L-1范围内共振散射增强强度(△I)与镍(Ⅱ)质量浓度呈线性关系.检出限(3S/N)为4.57μg·L-1,分别对50,200,400 μg·L-1镍(Ⅱ)标准溶液进行11次平行测定,测定值的相对标准偏差(n=6)依次为3.5%,3.0%,1.7%.据此提出了一种简单而快速的测定镍的方法.应用于测定水样中镍量,测得其平均回收率为98.5%.     

溴代十六烷基吡啶增敏共振光散射法测定乌拉地尔

以稀盐酸介质,固绿FCF作探针,表面活性剂溴代十六烷基吡啶作增敏剂,建立了测定乌拉地尔的共振光散射新方法。在稀盐酸存在下,乌拉地尔与固绿FCF-溴代十六烷基吡啶反应生成离子缔合物,使体系的共振光散射信号明显增强并产生新的共振光散射光谱,最大共振光散射(RLS)峰位于344 nm,乌拉地尔的质量浓度在0. 003～0. 28mg·L-1范围内与体系的共振光散射增强强度(ΔIRLS)呈线性关系,检出限为0. 0028 mg·L-1,加标回收率为98. 96%～101. 3%,相对标准偏差(RSD)(n=5)为2. 1%～2. 6%。该法灵敏、快速,用于市售乌拉地尔药物中乌拉地尔的测定,结果满意。     

曙红Y-SDS体系共振光散射法测定丁胺卡那霉素

在十二烷基磺酸钠存在下,于pH=5.5的Britton-Robinson(B-R)缓冲溶液中,丁胺卡那霉素(AMK)与曙红Y形成复合物,据此建立了以曙红Y作为共振光散射探针测定AMK的分析方法.在λ= 525 nm处,共振光散射强度(△IRLS)最大且光散射的强度与AMK的浓度在4～20 μg·5mL-1内成正比.该方法简便、快速、灵敏度高,对4.0 μg·5mL-1的AMK平行测定11次,检出限为0.0108 μg·5mL-1,RSD为3.23%,用于市售药品的分析测定,结果满意.     

蛋白质-SDS-罗丹明B体系的共振光散射光谱及其分析应用

研究了阴离子表面活性剂十二烷基硫酸钠(SDS),阳离子染料罗丹明B,与蛋白质相互作用的共振光散射(RLS)光谱及用于蛋白质的测定.实验表明,在pH 4.35的酸性介质中,SDS的共振光散射强度较小,它与蛋白质结合后,共振光散射强度能得到增强,但加入阳离子染料罗丹明B后,共振光散射强度显著增强.在λ=332.0 nm处,ΔIRLS最大,并且增强的共振光散射信号与蛋白质的浓度成正比.据此建立了一种测定蛋白质的新方法,该方法灵敏度高,对HSA的检出限达到1.9 ng/mL,线性范围为0.01～5.0 μg/mL.用于人血清样品中蛋白质的测定,回收率为94.0%～105.5%.     

共振散射光谱法测定环境水样中痕量锡（Ⅱ）

在pH 4.3的缓冲介质中,痕量锡(Ⅱ)对氯酚红-人血白蛋白-十二烷基硫酸钠体系的共振散射光谱有明显的减弱作用,共振散射强度的减弱程度(△I)与锡(Ⅱ)的质量浓度之间在0.2～4.0μg·L-1范围内呈线性关系,检出限(3S/N)为0.12μg·L-1,用于3件环境水样中痕量锡(Ⅱ)的测定,测定结果的相对标准偏差(n=6)小于3.5 %,加标回收率为95.5%～100.6%.     

酸性品红共振光散射法测定食品中的锌

建立了测定面制食品中锌的酸性品红共振光散射方法,研究了共振光散射的光谱特征及适宜的反应条件。在pH 6.88的Tris-盐酸缓冲介质及表面活性剂溴代十六烷基吡啶(TPB)存在下,Zn(Ⅱ)能够与酸性品红-TPB结合生成三元复合物,使共振光散射(RLS)显著增强并产生新的共振散射光谱,在最大散射峰379 nm处,体系的共振光散射增强程度(△IRLS)与0.008~0.25 mg·L~(-1)范围内的Zn(Ⅱ)呈线性关系,定量限为0.028 mg/100 g。方法简便、灵敏,加标回收率为98.9%~102%,相对标准偏差(RSD)(n=6)为2.0%~2.2%。方法用于面制食品中Zn的测定,结果满意。     

日落黄-十六烷基三甲基溴化铵共振光散射法测定核酸

以日落黄(Sunset Yellow,SY)为探针,十六烷基三甲基溴化铵(Hexadecyl Trimethyl Ammonium Bromide,CTMAB)为增敏剂,与核酸(DNA)形成SY-CTMAB-DNA可使体系共振光显著增强。在1.0 m L p H 7.5的BR缓冲溶液中,该体系共振光散射强度最大,反应可在室温5 min内迅速完成。在0.01~2.10μg·m L-1范围内散射强度(ΔI)与核酸的浓度成正比,检出限最低为2.76μg·L-1(n=6)。建立了一种简便、快速测定核酸的方法,并成功用于合成样品中核酸含量的测定,回收率在94.2%~108.5%,RSD为1.8%~3.2%,结果良好。     

以多胺为探针的DNA共振光散射光谱法测定

研究了三种常见多胺与小牛胸腺脱氧核糖核酸(DNA)作用的共振光散射光谱.发现在pH 2.21～9.15的B-R缓冲溶液中,小牛胸腺DNA与精胺的结合产生强烈的共振光散射,散射强度在343 nm波长处达到最大.小牛胸腺DNA的质量浓度在0.1～40 mg·L-1范围内与共振光散射强度呈线性关系,回归方程的相关系数为0.998 9,检出限为19μg·L-1.5倍于DNA浓度的蛋白质、核苷酸都不干扰DNA的分析测定,金属离子的允许浓度一般为1.0×10-6mol·L-1.     

乙醇敏化钛黄与蛋白质作用的共振光散射光谱研究及其分析应用

研究了在乙醇存在下钛黄（TY）与蛋白质作用的共振光散射（RLS）光谱特征 。基于RLS的增强,建立了一种测定蛋白质的新方法。考察了各种影响因素,在优 化条件下确定了RLS强度与蛋白质浓度之间的关系。当TY浓度为4 * 10~(-5)mol· L~(-1)时,牛血清白蛋白（BSA）、人血清白蛋白（HSA）和溶菌酶(lysozyme)的线 性响应范围分别为0.1～6.0 μg·mL~(-1), 0.1～5.0 μg·mL~(-1), 0.2～3.0 μg·mL~(-1),检出限分别为12.7 ng·mL~(-1), 11.6 ng·mL~(-1)和18.8 ng· mL~(-1)。三种合成样品五次平行测定的回收率和相对标准偏差（RSD）分别为96. 0%～102.3%和0.8%～3.2%。将该方法与经典的Bradford方法分别用于人血清试样中 蛋白的测定,两种方法的分析结果经F-检验和双总体T-检验证明无显著性差异。     

金纳米微粒共振光散射光谱探针测定维生素B_4-水溶性腺嘌呤的研究

建立了一种以金纳米微粒为探针共振光散射(RLS)法测定维生素B4的新方法.在弱酸性介质中(pH 4.2),金纳米微粒在635 nm有一最大共振散射峰.加入微量维生素B4后,金纳米微粒与维生素B4通过静电引力结合.形成了粒径较大的聚集体,导致RLS强度显著增强.研究了体系的共振光散射光谱特征和反应适宜条件,探讨了共振光散射增强的机理.结果表明,维生素B4质量浓度在0.1～5.0μg/mL 时与散射强度(△I)呈线性关系,检出限(3σ)为12.0 ng/mL,相对标准偏差(RSD)为2.2%.该方法已用于片剂中维生素B4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%.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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.