区带流动分析技术测定水中的氨氮

建立区带流动分析技术快速测定水中氨氮的方法。实验条件:进样体积为200μL,进样流量为10μL/s,加热温度为130℃,检测时间为6 min,检测波长:660 nm,混合方法:样品与试剂在储存管中往复运动混合。氨氮质量浓度与吸光度在0～1.0 mg/L范围内呈良好的线性关系,相关系数r~2=0.998 7,方法检出限为0.01mg/L。测定结果的相对标准偏差为1.8%～3.5%(n=7),样品加标回收率为95.5%～104.3%。该方法检测速度快,精密度与准确度较高,仪器携带方便,为氨氮污染的现场快速监测提供了一种新的手段。     

基于智能手机的数字图像比色法快速测定水中氨氮

建立基于智能手机与自制比色装置的数字图像比色法完成对水中氨氮的快速测定。以水杨酸钠为显色剂，三聚氰酸二氯钠为氧化剂，亚硝基铁氰化钠为催化剂，在碱性条件下与水中氨氮反应生成蓝色化合物，通过正交试验对反应条件进行优化。通过自制数字图像比色装置对显色溶液进行手机拍照分析，将经过色彩选择器（color picker）软件获得的RGB值和空白值基础上计算得出的欧氏距离D值应用于图片比色，对氨氮进行定量测定。氨氮质量浓度在0.05～2.0 mg/L与D值呈线性关系，相关系数（r）为0.998，检出限为0.03 mg/L，测定下限为0.12 mg/L。以空白水样为基体进行加标回收试验，氨氮回收率为98.7%～106.0%，测定结果的相对标准偏差为1.1%～7.4%(n=6)。实际样品该法分析结果与分光光度法基本一致。该方法可用于水样中氨氮的现场快速测定。     

电感耦合等离子体发射光谱法测定磷石膏中的水溶性五氧化二磷

建立电感耦合等离子发射光谱法(ICP–OES)测定磷石膏中水溶性五氧化二磷含量的方法。用超声波快速提取磷石膏中的磷,在178.284 nm波长下,用CID固体检测器测定样品溶液的光谱强度。五氧化二磷的质量浓度在0.007~200 mg/L范围内与光谱强度线性关系良好,线性相关系数r=0.999 96,检出限为0.006 9 mg/L。样品加标回收率在98%~102%之间,测定结果的相对标准偏差为0.95%~1.11%(n=6),该方法的测定结果与国标法基本一致。该法简便、快速,适合磷石膏中水溶性五氧化二磷的测定。     

氨氮TNT试剂在水环境应急监测中的应用

为了精准、快速检测环境应急事件中水质氨氮的质量浓度,提供及时、可靠的监测数据支持,依据国标方法,选用安全、高效、低耗的氨氮TNT试剂对饮用水源地、黑臭河道及工业污水监控区域的水环境应急监测氨氮样品进行多批次测试,将其结果与国标方法的测试结果进行比较,并对氨氮有证标准样品进行同步验证。氨氮TNT试剂测定水中氨氮的检出限为0.015 mg/L,氨氮测定结果的相对标准偏差为2.0%~4.7%(n=6),多批次检测的加标回收率为92%~108%,有证标准样品验证测试的相对误差为–1.1%~2.5%。用F检验、t检验法证实氨氮TNT试剂应用结果能够满足水环境应急监测中氨氮测试的精密度、准确度要求且具备分析高效、节能环保等优点。     

气相色谱法测定甘宝素中的甲苯残留量

采用毛细管气相色谱法快速测定甘宝素产品中的甲苯残留量。样品经甲醇稀释,氢火焰离子化检测器检测,外标法计算含量。甲苯的质量浓度在3.2~25.6 mg/L范围内与色谱峰面积线性良好,相关系数r=0.999 3,方法的检出限为1.16 mg/L,样品的加标回收率为96.5%~102.8%(n=6),测定结果的相对标准偏差为3.2%~4.5%。该方法操作简便,灵敏度高,适合于实际生产中甲苯残留量的快速测定。     

连续流动法同时测定污水中氨氮和总磷

采用连续流动分析法测定污水中氨氮、总磷的含量。比较了污水样品不同的稀释倍数对测定结果的影响。实验结果表明:氨氮和总磷的质量浓度在0.1~8 mg/L范围内线性良好,线性相关系数均为0.99997;测量结果的相对标准偏差分别为2.01%,0.84%(n=7);方法检出限分别为0.012,0.009 mg/L;质控样测量值均在标示值范围内;样品加标回收率为93.4%~101.1%。污水的洁净程度对测定结果影响较大。洁净度高的污水,直接测定与稀释后测定,测定值无显著性差异;而洁净度低的污水,直接测定与稀释后测定结果差异比较大。该法采用全谱直读CCD检测方式,灵敏度高,稳定性好,无光谱干扰,且支持氨氮和总磷同时测定,方便快捷,适合污水中氨氮和总磷的测定。     

高温水解-离子色谱法同时测定再生锌原料中氟和氯

采用自制的高温水解装置处理样品,结合离子色谱法测定了再生锌原料中氟、氯的含量。试样在1 000℃高温下通入氧气与水蒸汽进行水解反应,以NaHCO_3(6.0mmol/L)与Na_2CO_3(2.4mmol/L)的混合溶液作为淋洗液,经SH-AG-1保护柱及SH-AC-3分离柱分离,测得F-在0~10 mg/L、Cl-在0~50mg/L范围内浓度与峰面积呈线性关系,相关系数分别为r=0.999 8和r=0.999 9,检出限分别为0.020mg/L与0.033 mg/L。分析再生锌原料中氟、氯的加标回收率分别在95.70%~102.5%和96.72%~101.3%,相对标准偏差(n=11)分别在2.1%~6.6%和2.0%~5.8%。方法对再生锌原料中氟(0.010%~1.00%)和氯(0.050%~5.00%)测定,结果满意。     

自动电位滴定法测定工业碳酸钠中氯化钠含量

采用自动电位滴定法,用硝酸银标准溶液作为滴定剂,测定工业碳酸钠中氯化钠含量。方法检出限为0.13mg/L,不同含量氯化钠样品加标回收率为99.7%~100.3%,相对标准偏差(n=5)为0.17%~2.0%,方法简单、快速,精密度和准确度高,适合大批量快速分析样品。     

离子色谱双柱法测定硝酸中痕量氯离子

采用离子色谱双柱串联法分离硝酸样品,以离子色谱电导检测法测定硝酸滤液中的痕量氯离子。氯离子浓度在0.01~0.30 mg/L范围内与色谱峰面积成线性关系,对硝酸样品进行测定,氯离子的加标回收率为96.5%~99.0%,测定结果的相对标准偏差为1.84%~2.83%(n=5)。     

微量水体中氨氮的快速检测

以纳氏试剂比色法为基础,同倍比缩小样品体积以及所需试剂的体积,并对其分析测试步骤进行了适当的调整和改进,在多功能酶标仪上进行比色分析测定氨氮含量。分别对两种氨氮浓度(0.5 mg/L和2 mg/L)进行了8次重复性测试,相对标准偏差(RSD)为7.5%和3.6%,水样加标回收率在96.5%~106.1%之间。方法可以为微量水体的氨氮含量的确定提供依据。     

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.     

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.     

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.     

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.     

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.