二氧化钛-硒化镉修饰电极电化学发光法测定甘氨酸

以二氧化钛和硒化镉复合膜修饰的玻碳电极(TiO_2/CdSe/GCE)作为工作电极,建立了一种测定甘氨酸的电化学发光(ECL)新方法。在强碱性溶液中,TiO_2/CdSe/GCE在鲁米诺溶液中会产生明显的电化学发光信号,而甘氨酸对该体系的电化学发光信号有较强的增敏作用。考察了TiO_2/CdSe复合物的比例、缓冲溶液的pH、发光试剂的浓度等条件对ECL强度的影响。最佳实验条件下,甘氨酸浓度在2.5×10~(-7)~1.0×10~(-10)mol/L范围内与相对ECL强度呈现良好的线性关系,检测限(S/N=3)为3.3×10~(-11)mol/L,方法用于乳酸饮料中甘氨酸的测定,结果令人满意。     

果汁饮料中甘氨酸添加剂的荧光分光光度分析

甘氨酸是生产氨基酸的基本原料,在食品工业中用作酿造、肉食加工和清凉饮料的配方,是重要的添加剂,其测定方法主要是茚三酮比色法和甲醛法。在醋酸与醋酸钠的缓冲介质中,将甘氨酸与乙酰丙酮以及甲醛按一定比例混合,在沸水浴中加热后能够发生灵敏的显色反应,曾有利用该反应进行甘氨酸测定的报道呤,试验表明该产物能够发生较强的荧光,基于此建立了一种测定甘氨酸的方法。本实验详细探讨了该反应的最佳条件以及共存离子的影响,对饮料中低浓度甘氨酸的测定有一定的意义。     

偶氮氯膦Ⅲ分光光度法测定铁铝铜镍合金中钇

偶氮氯膦Ⅲ可在较强的酸性介质中与各稀土元素呈显色反应,已广泛用于稀土元素总量的测定。本文研究了在0.2N硝酸、40%乙醇介质中钇与偶氮氯膦Ⅲ的显色反应,结果表明,显色可瞬时完成,络合物最大吸收位于670nm,其摩尔吸光系数为1.2×10~5,桑德尔灵敏度为0.00074微克/厘米~2;0—12微克钇/     

牛磺酸和甘氨酸在D290树脂上的离子交换平衡

研究了牛磺酸与甘氨酸在阴离子树脂D290上的离子交换平衡.采用静态法分别进行牛磺酸/氢氧根/D290树脂和甘氨酸/氢氧根/D290树脂体系的离子交换平衡实验并测定等温线;在不同的离子强度下进行了牛磺酸/甘氨酸/氢氧根/D290阴离子交换树脂体系的离子交换平衡实验,测定牛磺酸和甘氨酸在碱性条件下的竞争交换平衡等温线.实验结果表明,牛磺酸在D290阴离子交换树脂上的交换量大于甘氨酸的交换量,阴离子交换树脂对牛磺酸和甘氨酸的选择性系数分别为STau-,OH-=2.55,SGly-,OH-=1.65.在牛磺酸/甘氨酸/氢氧根/D290树脂体系中,D290树脂对牛磺酸/甘氨酸/氢氧根3种离子的选择性从高到底顺序是:牛磺酸＞甘氨酸＞氢氧根.树脂对牛磺酸的选择性要大于对甘氨酸的选择性.随着溶液中离子强度的增大,树脂对牛磺酸与甘氨酸之间的选择性下降.     

基于氧化还原体系纸芯片法对血清尿酸含量的快速检测

建立了以纸芯片为分析平台的尿酸含量快速检测方法.基于尿酸的还原性,以FeCl3为氧化剂组成氧化还原体系,以邻二氮菲为显色剂对反应产物Fe2+进行显色,根据显色强度对尿酸含量进行测定.结果 表明,当FeCl3与尿酸比例为1.6∶1,反应10 min,显色剂pH 7.4时显色最佳.显色强度(RGB值)与尿酸浓度在1.19～5.95 mmol/L范围内呈良好线性关系,相关系数为0.9998.方法 的检测限为0.342 mol/L,日内和日间相对标准偏差分别为0.42％和0.47％.15种共存物质在允许误差范围内均无干扰.测得牛血清中尿酸含量为0.238 mmol/L,平均回收率为96.4％.该方法可用于血清中尿酸含量检测.     

N-邻羟基苯基氮氧方酸与铬显色反应的研究和应用

研究了N 邻羟基苯基氮氧方酸与Cr(Ⅵ )的显色反应 ,在柠檬酸 柠檬酸铵缓冲溶液中 ,发生氧化还原反应生成棕黄色水溶性化合物。其最大吸收波长在 4 10nm处 ,ε值为 9.5× 10 3,线性范围为 0～ 75 μg/2 5ml。此显色反应可用于铬的光度测定 ,其结果与使用二苯基碳酰二肼吻合     

分光光度法和比色卡法快速测定蜂蜜中羟甲基糠醛

建立了分光光度法和比色卡法快速测定蜂蜜中羟甲基糠醛(HMF)的方法。通过优化测定条件和显色体系,选择最佳参数,在此基础上制作了比色卡。结果表明,最佳测定波长为550 nm,显色温度为25℃,显色时间为5 min。对甲苯胺溶液的最佳质量浓度为0.15 g/m L,巴比妥酸溶液的最佳质量浓度为5 mg/m L,以体积比为5:1混合后制成显色混合液。该显色混合液可保持稳定10 d。经优化后的分光光度法,在0~8μg/m L范围内HM F浓度与吸光度有良好的线性关系,相关系数为0.9997,加标回收率为95.4%~103.5%,相对标准偏差为0.6%~2.9%。所研制的比色卡的检测范围为0~60 mg/kg。以上两种方法对实际样品的检测结果与国标法的结果基本相符,方法适合于蜂蜜中HMF含量的快速检测。     

混合微乳液对Mn(Ⅱ)-水杨基荧光酮显色反应的增敏研究

研究了在O/W混合微乳液:CTMAB-OP/n-C_5H_(11)OH/n-C_7H_(16)/H_2O介质中,Mn(Ⅱ)-SAF的显色反应。结果表明,在此微乳液介质中,Mn(Ⅱ)-SAF显色反应的ε_(578)=1.6×10~5,与以CTMAB/n-C_5H_(11)OH/n-C_7H_(16)/H_2O为反应介质的ε_(575)=1.3×10~5比较,具有更大的增敏作用和稳定性。Mn(Ⅱ)0～2.5Pg/10ml范围内具有良好的线性关系。方法用于测定天然水中的锰,结果满意。     

吸附镍(Ⅱ)的甘氨酸共价修饰玻碳电极的制备及应用于葡萄糖的无酶催化氧化测定

将玻碳电极(GCE)置于0.01 mol·L-1甘氨酸的[Bmin]PF6离子液体溶液中,于0~2.0 V电位间以50 mV·s-1扫描速率进行循环伏安扫描10圈,从而制成通过C-N共价键结合的甘氨酸修饰玻碳电极(Gly/GCE)。将此修饰电极置于0.1 mol·L-1氯化镍溶液中浸泡6 h,镍(Ⅱ)就吸附于甘氨酸修饰层上,制成了吸附着镍(Ⅱ)的Gly/GCE,记作Ni(Ⅱ)-Gly/GCE。此电极在0.1 mol·L-1氢氧化钠溶液中由于Ni2+/Ni3+电对的媒介作用对葡萄糖产生无酶催化氧化反应,导致在+0.55 V(vs.SCE)处氧化峰电流明显增高,电流响应值与葡萄糖浓度在1×10-6~2×10-3mol·L-1范围内呈线性关系,其检出限(3S/N)为3×10-7mol·L-1。据此,提出了测定葡萄糖的计时电流法,并应用于血清样品中葡萄糖的测定,所得结果与用Dimension RXL-MAX自动化分析仪的测定结果相符。     

A STUDY OF THE STABILIZING CAPACITY OF GLYCINE TOWARD SILVER CLUSTER Ag42+ IN AQUEOUS SOLUTION

本文用溴钨灯照射含异丙醇、甘氨酸(稳定剂)和硝酸银的水溶液制得非金属银团簇Ag₄²⁺(λmax=275nm),其产率随甘氨酸量的增加而增加,并且在空气中甘氨酸可以稳定其数天。对所得结果以及Ag₄²⁺在照相潜影形成过程中的可能作用进行了讨论。本文用溴钨灯照射含异丙醇、甘氨酸(稳定剂)和硝酸银的水溶液制得非金属银团簇Ag₄²⁺(λ_max=275nm),其产率随甘氨酸量的增加而增加,并且在空气中甘氨酸可以稳定其数天。对所得结果以及Ag₄²⁺在照相潜影形成过程中的可能作用进行了讨论。     

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.