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。     

催化显色反应测定痕量铜

在催化显色体系中引入合适的活化剂能显著地提高其反应灵敏度,通过实验,我们观察到,乙醇对Ｃｕ－邻苯二酚－Ｈ２Ｏ２的催化显色反应有明显的活化增敏作用。研究了该体系的实验条件,并成功应用于食品和发样中痕量铜的测定。１　试剂与仪器７２３０型分光光度计;ｐＨＳ－２型酸度计。铜（Ⅱ）标准贮备液浓度１ｍｇ／ｍＬ,工作液稀释为１μｇ／ｍＬ;邻苯二酚溶液０．２ｍｏｌ／Ｌ;３０％Ｈ２Ｏ２溶液、ｐＨ５．５,ＨＡｃ－ＮＨ４Ａｃ缓冲溶液。试剂均为分析纯,水为去离子水。２　实验方法在２５ｍＬ比色管中分别加入２．５ｍＬ的邻苯…     

甲醛被动式检气管的研制

在气体分子扩散和化学吸收的原理基础上，研制了一种测量甲醛气体含量的被动式检气管。检气管内的惰性担体上浸渍了酚酞亚硫酸钠溶液，遇甲醛后显色。显色长度的平方与甲醛浓度及采样时间的乘积成线性关系。检出下限为０．１７μｇ／ｍｌ（采样１．５ｈ）。它集采样与分析为一体，可以快速测定木材厂的甲醛储运房内气体中甲醛气体浓度。检气管结构简单，携带和操作方便。与传统的注射器采样比色分析法对比，相对偏差在±１４％内。检气管在避光条件下保存，保存期为三个月。     

食品中添加剂甘氨酸的比色分析

研究了甘氨酸与乙酰丙酮-甲醛试剂显色反应的最佳条件、反应机理及共存物质的影响等。开发出食品中添加剂甘氨酸的比色分析方法。在pH6.5乙酸盐介质中,显色产物的λ_(max)为415nm,甘氨酸含量在0～200ug/10mL范围内符合比尔关系,摩尔吸光系数ε为2.3×10~3L/mol·cm。     

基于化学比色法的TATP和DADP现场快速检测及区分

基于酸性条件下过氧化物爆炸物快速分解产生的H₂O₂与草酸钛钾发生特征显色反应，建立了三过氧化三丙酮(TATP)、二过氧化二丙酮(DADP)的现场快速检测及区分方法。结果表明，质量分数为60%的H₂SO₄是分解反应最佳引发剂，1 min内即可实现快速显色及区分；TATP和DADP目视检出限分别为3.0×10^-5 mol/L和4.05×10^-3 mol/L。根据比色分析结果制作标准比色卡，可实现过氧化物爆炸物的定性和半定量分析。TATP和DADP在基质样品中的加标回收率为95.3%～107.4%，相对标准偏差为0.5%～7.6%。通过控制酸的浓度，或比较相同反应时间和相同样品浓度下的显色效果，可实现TATP和DADP的区分。     

一种蜂蜜中羟甲基糠醛的快速检测方法

本发明公开了一种蜂蜜中羟甲基糠醛(HMF)的快速检测方法,包括如下步骤:(1)样品的制备。准确称取7.5 g蜂蜜样品置于一个小烧杯中,加入10 m L蒸馏水混匀,用玻璃棒搅匀后,转移至25 m L的容量瓶内,加蒸馏水定容至标线,摇匀;(2)显色。取1.00 m L待测样品于具塞刻度试管中,然后向试管中加入3 m L混合溶液,混匀后显色5 min;(3)检测。通过显色后溶液的颜色与比色卡对比,确定出HMF的含量值。本发明具有所用试剂简单、不需要复杂的条件和仪器设备、操作简便、快速的特点。     

贵金属元素分析化学(Ⅰ)——γ-酸(7-氨基-1-萘酚-3-磺酸)作为测定微量锇的显色试剂

关于锇的显色试剂在Snell的专著中已有综述。但现有比色用有机显色剂的灵敏度还不能满足矿石中微量锇的测定要求。作者曾报导过应用γ-酸作为微量锇的显色试剂,该试剂测锇的ε_(500nm)达50万升/摩尔·厘米以上,可与催化比色法测锇的灵敏度比美。γ-酸与锇(Ⅷ)在常温下显色很慢,但在加热至沸时则能很快显色完全,呈橙红色;常与锇共存的钌(Ⅷ)则不需加热就可立即显出绿色,但灵敏度远不及与锇(Ⅷ)的反应高,加热煮沸后变化也不大。因此可允许在有较多量钌存在下测锇。     

比色法快速测定大豆低聚糖-棉子糖的方法

本发明提供的是一种比色法快速测定大豆低聚糖-棉子糖的方法。首先配制测定用试剂，分别制备出1％大豆低聚糖-棉子糖标准液母液；用母液制备出不同浓度的溶液，向这些不同浓度的溶液中添加测定用试剂，在100℃温度下反应10min；之后利用分光光度计在波长540nm下测定出制作出浓度和吸光度之间的标准曲线，得到标准曲线的计算公式；其次配制未知样品溶液，     

燃烧-吸收-比色法测定高纯三氧化钨中微量硫

本文提出了测定高纯三氧化钨中微量硫的方法。试样在1400℃(燃烧)所含硫及硫化物与氧反应生成二氧化硫,用氯化汞酸钠溶液吸收,形成稳定的二氯亚硫酸根络合物。该络合物再与甲醛缩合,并与褪色品红作用,生成紫红色的化合物,在560nm处进行比色测定。对氯化汞酸钠的用量;显色剂、褪色品红与甲醛用量对显色的影响;显色时间及颜色的稳定性、试样燃烧吸收时间以及降低空白值等条件进行了试验。确定了最佳的测定条件。方法测定下限为0.5ppm,相对标准偏差±4.8％。     

应用2-氯苯甲醛与苯肼的衍生化反应于2-氯苯甲醛的荧光光度测定

研究了2-氯苯甲醛(CBZD)与苯肼的衍生化反应,在pH 1.0的乙醇/水溶液中,2-氯苯甲醛与苯肼形成荧光希夫碱,研究了希夫碱的荧光性质,希夫碱的荧光激发波长eλx=552.0 nm,发射波长eλm=299.2 nm.其荧光强度与2-氯苯甲醛浓度在0~120μg.L-1范围内呈线性关系,检出限为0.2μg.L-1。方法应用于矿泉水、自来水、生理盐水、葡萄糖注射液中2-氯苯甲醛的测定。     

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.     

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.     

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.     

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.     

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.     

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.