催化动力学光计法测定微量碘的研究

基于微量碘离子对高碘酸钠氧化甲基紫反应的催化作用，建立了测定微量碘的动力学光度法。方法检出限０．２２μｇ／ｍＬ线性范围０．３０－１．４０μｇ／ｍＬ，包括其它卤素在内的大多数阴离子、阳离子不干扰测定，用于食盐中微量碘的测定，有满意的结果。     

二氯荧光素—氯化十六烷基吡啶荧光猝灭法测定微量碘

本文研究了用二氯荧光素（ＤＣＦ）－氯化十六烷基吡啶（ＣＰＣ）体系荧光猝灭法测定微量碘。在ｐＨ为２．８－３．１的Ｈ２ＳＯ４介质中，检出限为０．３０μｇ／２５ｍｌ线性范围为０．３０－２．００μｇ／２５ｍｌ，本法灵敏度高，选择性好，适用于微量碘的测定。     

过碘酸钾氧化鸡冠花红动力学光度法测定食品中痕量碘

基于硫酸介质中，草酸钠作活化剂，碘催化过碘酸钾氧化鸡冠花红而使其褪色的反应，建立了测定痕量碘的新方法。方法灵敏、简便、选择性好。测定碘的线性范围为０－２０μｇ／Ｌ；检出限为０．６６μｇ／Ｌ。用于食品中痕量碘的测定，结果满意。     

流动注射催化动力学光度法测定碘的研究

本文采用流动注射技术,利用微量碘离子催化铁的硫氰酸配合物与亚硝酸钠的褪色反应,实现水中微量碘离子的催化动力学光度测定。该法测定碘离子的线性范围是1．0～7．0μg／mL,检出限为0．5μg／mL,相对标准偏差为5．0％。方法用于实际水样中微量碘离子的测定,结果令人满意。     

异硫氰酸荧光素荧光猝灭法测定痕量碘酸根

碘酸根与碘离子反应生成游离碘使异硫氰酸荧光素的荧光猝灭,λｅｘ为４８７ｎｍ,λｅｍ为５１７ｎｍ,碘酸根含量在２－８μｇ／Ｌ范围内与荧光猝灭程度有良好线性关系,检测限为０．７４μｇ／Ｌ,该法灵敏度高,操作简便,用于含碘含盐中微量碘酸根的测定,结果满意。     

靛蓝胭脂红-溴酸钾体系催化光度法测定微量碘

研究了在室温及0．4mol/L H2SO4介质中碘离子对KBrO3氧化靛蓝胭脂红褪色反应的催化作用,建立了一种测定微量碘的新方法。碘离子浓度在0．20－2．0μg/mL范围内与△A呈线性关系,检测限为0．14μg/mL。多数常见离子无干扰。可用于海带中微量碘的测定。     

Pt（Ⅳ）—三氯偶氮胂—溴酸钾催化分光光度法测定微量铂的研究

在硫酸介质中，微量铂的存在对溴酸钾氧化三氯偶氮胂的褪色反应有明显的催化作用，研究了催化分光光度法测定微量铂的新方法。该法灵敏度高，测定铂的线性范围为０．００－０．４０μｇ／１０ｍＬ。该方法已用于铂催化剂中微量铂的测定，结果令人满意。     

氯化三辛基甲基胺萃取原子吸收法测定微量锑的研究

本文在ＫＩ－Ｈ２ＳＯ４体系中，研究了锑的碘络阴离子的萃取行为，并结合火焰原子吸收法测定了微量锑，萃取体积比（Ｖ水／Ｖ有）为２０，线性范围为０－２μｇ／ｍｌ，锑的特征浓度为０．５μｇ／ｍｌ／１％吸收，检出限为０．１μｇ／ｍｌ。     

Pt(Ⅳ)-三氯偶氮胂-溴酸钾催化分光光度法测定微量铂的研究

在硫酸介质中，微量铂（Ⅳ）的存在对溴酸钾氧化三氯偶氮胂的褪色反应有明显的催化作用，研究了催化分光光度法测定微量铂的新方法。该法灵敏度高，测定铂的线性范围为０．００～０．４０μｇ／１０ｍＬ。该方法已用于铂催化剂中微量铂的测定，结果令人满意。     

基于重氮化反应分光光度法测定微量亚硝酸根

基于在盐酸介质中微量亚硝酸根与罗丹明ＧＯ发生的重氮化褪色反应,建立了光度法测定微量亚硝酸根的新方法,并对机理进行了初步讨论。方法的线性范围为０．０２－０．４μｇ／ｍＬ,检出限为０．０２μｇ／ｍＬ。方法已用于水呈微量亚硝酸根的测定。     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.