SPE-NPD气相色谱法测定水中莠去津和甲草胺除草剂

建立了以固相萃取-大口径毛细柱-NPD气相色谱法测定水中莠去津和甲草胺除草剂含量的方法.在优化的条件下,两种物质的响应值与浓度有良好的线性关系,灵敏度高,此方法测定水中莠去津的最低检出浓度为0.0002mg/L,而甲草胺则为0.0006 mg/L.该方法用于实际水样分析,样品的回收率为92.5%～114%.该方法具有预处理简便,分析速度快,干扰少等优点.     

直接进样毛细管气相色谱法测定水中乙醛和丙烯醛

建立气相色谱法测定水中乙醛和丙烯醛的方法.直接进样用大口径填充毛细管柱进行分离分析,分离度好,灵敏度高,水中乙醛和丙烯醛的栓出浓度分别为0.02mg/L、0.01mg/L;样品加标回收率乙醛为102%～103%,丙烯醛为94.8%～!96.8%;6次平行测定结果的相对标准差不大于5.8%(n=6).该方法简便、快速、准确、重现性好.适合各种水中乙醛和丙烯醛的同时测定     

离子色谱法测定水中的腐胺、尸胺和组胺

建立了离子色谱法快速测定水中腐胺、尸胺和组胺的方法, 考察了淋洗液条件、干扰离子对实验的影响, 优化了分离条件, 进行了方法学评估. 实验结果表明: 3种物质可以在9 min内达到基线分离, 腐胺和尸胺在1.0～20.0 mg/L、组胺在1.0～100.0 mg/L的浓度范围内, 峰面积和浓度之间线性关系良好, 保留时间的RSD＜0.01%, 峰高的RSD＜2.32%, 峰面积的RSD＜2.08%, 回收率在92.0%～107.4%之间. 本方法适用于水中腐胺、尸胺和组胺的测定.     

仪器装置与实验技术余氯、总氯现场快速测定仪的研制和应用

研制了一种基于光度法现场测定水中余氯、总氯的手持式仪器 ,开发了相应的专用试剂包 ,讨论了影响该仪器分析性能的主要因素。用该仪器和试剂现场测定水中的余氯和总氯 ,线性范围是 0 .0 1～ 5 .0mg/L ;RSD <3% ;单个样品分析时间不超过 3min。     

流动注射在线分析法测定水源水中的总氮

采用流动注射在线分析法测定水源水中总氮的含量。研究了样品预处理过程中水样浊度干扰、实验用水、试剂纯度选择、试剂配制及存放、气泡的干扰、干扰物的消除、显色剂浓度优化等对实验结果的影响。在磺胺和盐酸萘乙二胺溶液的质量浓度分别为35、1 g/L的最优条件下，水源水中的总氮质量浓度在0.040～10.0 mg/L范围内与吸收峰面积具有良好的线性关系，相关系数为0.999 9。水源水中总氮的检出限为0.010 mg/L，加标回收率为92.5%～105%，测定结果的相对标准偏差为0.22%～1.10%(n=6)。该方法运行成本低，操作方便，分析速度快，稳定性和安全性好，适用于大批量水源水中总氮的测定，能够满足水源水监测的技术要求。     

直接进水样气相色谱法测定饮用水源水中吡啶

建立直接进水样气相色谱法测定饮用水源水中吡啶的分析方法.吡啶浓度在0.1～5.0 mg/L范围内与峰面积呈良好的线性关系,相关系数为0.9999,检出限为0.03 mg/L.相对标准偏差不大于4.91%(n=5),回收率为81%～107%.实验证明,该方法符合国标GB 3838-2002的要求,与推荐方法相比具有操作简便快速、环保安全等优点.     

重铬酸钾光度法快速测定水中化学需氧量

建立快速测定水中化学需氧量(COD)的重铬酸钾光度法。样品消解温度为165℃,消解时间为15 min。当水中含有氯离子时,可加入硫酸汞掩蔽剂消除氯离子影响,其加入量按每毫克氯离子加入20 mg硫酸汞计算。该方法检测范围为20~800 mg/L,当水中COD质量浓度大于800 mg/L时应先进行稀释,然后测定;当COD质量浓度小于20 mg/L时,可以采用真空蒸馏法浓缩,以提高COD质量浓度。采用该方法对COD质量浓度为300 mg/L的标准溶液进行测定,测定结果的相对标准偏差为0.7%(n=6),相对误差为-2.0%。分别采用所建方法和国家标准方法HJ 828—2017(重铬酸钾回流消解滴定法)测定两个不同水样,相对偏差分别为-1.6%和-1.1%。该方法适用于水中COD的快速测定。     

气相色谱法测定水中的松节油

研究了测定水中松节油的气相色谱法.采用二硫化碳萃取,DB-5型毛细管柱分离,氢火焰检测器(FID)检测水中松节油的含量.松节油浓度在1. 00～25. 0 mg/L范围内与色谱峰面积呈良好的线性关系,线性相关系数r=0. 9996.加标回收率为86. 3%～91. 3%,测定结果的相对标准偏差为8. 7%(n=6).该法可满足地表水环境质量标准的要求.     

电感耦合等离子体原子发射光谱法同时测定不锈钢中的11种元素

建立电感耦合等离子体原子发射光谱法同时测定不锈钢中硅、锰、磷、铬、镍、钼、钴、钒、钛、铜、铝11种元素含量的方法。样品采用盐酸溶液溶解,硝酸氧化,在优化的实验条件下,用电感耦合等离子体原子发射光谱法测定各元素含量。磷的质量浓度在0～5 mg/L范围内,钛、铝、钴的质量浓度在0～10 mg/L范围内,钒的质量浓度在0～15mg/L范围内,铜、硅、钼的质量浓度在0～20 mg/L范围内,锰的质量浓度在0～50 mg/L范围内,镍的质量浓度在0～80 mg/L范围内,铬的质量浓度在0～100 mg/L范围内与光谱强度呈良好的线性关系,相关系数均大于0.998,方法检出限为0.002～0.035 mg/L。测定结果的相对标准偏差均小于2%(n=6),加标回收率为97.9%～105.6%.该方法快速、准确,适用于实际生产中不锈钢样品的批量检测。     

固相萃取-气相色谱法测定水中甲胺磷

建立固相萃取-气相色谱法测定水中甲胺磷的方法。以甲醇为洗脱剂,采用椰壳活性炭固相萃取柱对水样富集,将洗脱液氮吹至近干,然后用乙酸乙酯定容至1 mL,采用气相色谱火焰热离子检测器（FTD）检测。甲胺磷的质量浓度在0.1～1.0 mg/L范围内与色谱峰面积线性关系良好,相关系数为0.998,甲胺磷的检出限为0.000 1 mg/L,定量限为0.000 4 mg/L。采用所建方法对实际水样进行测定,地表水和自来水样品加标回收率分别为83.2%～90.8%、87.8%～98.8%,测定结果的相对标准偏差分别为5.5%～8.3%、7.7%～10%(n=6)。该方法操作简单、有机溶剂用量小,可用于生活饮用水及水源水中甲胺磷的测定。     

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.     

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.     

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.     

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.     

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.     

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.