气相色谱法同时测定西草净、丁草胺和噁草灵

 采用气相色谱法,以癸二酸二正丁酯为内标物,对新研制的复合型稻田除草剂26％丁··西乳油进行了一次性定量分析。色谱条件为5％SE-302m×3mm的玻璃柱,柱温为210℃,检测温度为230℃。方法的回收率为98．62％～100．77％,线性相关系数大于0．999。方法准确、简便、快速。     

固相萃取/高效液相色谱法测定水中痕量硝磺草酮

建立了一种固相萃取/高效液相色谱(SPE/HPLC)测定水中痕量硝磺草酮的方法。水样用磷酸调至p H 3.0~4.0,经C18固相萃取柱富集、乙腈-水(1∶1)洗脱后,用HPLC/紫外检测器测定。测定条件为:流动相为乙腈-磷酸水溶液(45∶55,p H 3.0),流速0.5 m L/min,色谱柱为Thermo Hypersil-C18柱(250 mm×4.6 mm,5μm),柱温30℃,检测波长233 nm。结果表明:在0.4~20μg·L-1范围内,硝磺草酮的线性良好,方法检出限为0.039μg·L-1。加标浓度为1,5,10μg·L-1时,硝磺草酮的回收率为90.3%~94.7%,相对标准偏差为3.5%~4.6%。应用该方法测得实际水样中硝磺草酮的加标回收率为89.9%~93.2%。该方法具有快速、简便、灵敏等优点,可用于水样中痕量硝磺草酮的测定。     

反相高效液相色谱法同时测定土壤中莠去津,氰草津残留量方法研究

提出了用高效液相色谱法同时测定土壤中莠去津、氰草津残留量的方法。用甲醇／乙腈提取，石油醚脱脂，中性氧化铝小柱净化，最后用Ｎｏｖａ－ＰａｋＣ１６柱进行ＨＰＬＣ分析，流动相：甲醇－水（５５＋４５），吸收波长 ２２８ ｎｍ，流速０． ７ ｍＬ／ｍｉｎ．莠去津最低检出限为 ０．３ ｎｇ，氰草津为０．２ ｎｇ。回收率分别为莠去津８３．４％～１０２．３％，氰草津 ８２．４％～９３．５％．     

离子色谱柱后衍生光度法检测食品中含硫的阴离子化合物

研究了一种离子色谱柱后衍生直接光度法测定食品中含硫阴离子化合物．采用IonPacAS22A分析柱（250mm×4mm）,IonPacAG22A保护柱（50mm×4mm）,4．5mmol·L^-1碳酸钠和0．8mmol·L^-1碳酸氢钠等度淋洗,柱温设为室温,衍生试剂是0．24g·L^-1碘液和0．2％磷酸（V：V）的混合溶液,检测波长为288nm．样品用20mg·L^-1草酸溶液萃取,经高速离心、上层清液过C18预处理小柱及0．45μm过滤膜后直接进样．实验结果表明,方法的检测限硫离子、甲醛合次硫酸氢根离子、亚硫酸根离子、硫氰酸根离子及硫代硫酸根离子分别为0．006,0．004,0．006,0．006和0．007mg·L^-1一天之内的相对标准偏差分别为4．86％,3．24％,3．76％,2．68％和2．07％．实际样品测定,除硫离子外,方法的回收率分布在67．2％～116．5％之间,硫离子的回收率为38％～45％．     

对土壤及玉米植株中均三氮苯类除草剂的残留分析

土壤或玉米植株样品用Ｖ（甲醇）∶Ｖ（乙腈）＝１∶１提取,提取液用石油醚净化后,浓缩液过Ｃ１８小柱净化,最后用Ｎｏｖａ－ＰａｋＣ１８柱进行ＨＰＬＣ分析。回收率：氰草津为８２．４％～９９．８％,莠去津为８５．６％～１０２．３％,西草净为８９．１％～１０８．４％。     

草一光可湿性粉剂活性成分的反相高效液相色谱分析

采用反相高效液相色谱法同时测定15.5％草一光可湿性粉剂中的异丙甲草胶和苄嘧黄隆两种活性成分,以V（甲醇）：V（酸性水）=70：30作为流动相,采用ZORBAXSB-C18色谱柱。方法回收率达98.1％～102.6％,变异系数为0.4％～0.8％。     

HPLC法拆分高效盖草能乳油中吡氟氯禾灵的光学异构体

建立了高效盖草能乳油中有效成分精吡氟氯禾灵的快速、准确的高效液相色谱分析方法;在流动相为正已烷-异丙醇（体积比70：30）,流速1.0mL/min,检测波长为280nm,柱温为25℃时,高效盖草能乳油中吡氟氯禾灵的光学异构体在Chiralcel OK柱得到很好分离;方法的标准偏差和相对标准偏差分别为0.46g/L和0.43%     

反相高效液相色谱法测定葛根素和大豆苷元

利用反相高效液相色谱法,配以二极管阵列检测器测定了心可舒片中的葛根素和大豆苷元,建立了一种心可舒片的质量控制方法。色谱柱为C18柱,流动相为乙腈和0．02mol／L磷酸二氢钾,柱温为25℃,流速为0．8mL／min,梯度洗脱,检测波长为250nm。葛根素和大豆苷元的平均回收率分别为97．3％和101．4％：RSD为0．6％和1．9％。     

固相萃取-高效液相色谱法测定水中的多环芳烃

建立了固相萃取-一高效液相色谱法测定水中多环芳烃的方法。水样经L-18固相萃取柱吸附后用二氯甲烷洗脱,氮吹干后换甲醇溶剂。反相C18柱为色谱柱;水、甲醇为流动相进行梯度洗脱,流速为1．0mL／min;柱温为30℃;检测器为荧光检测器、紫外检测器。方法的检出限为0．00006-0.03μg／L,回收率为80％～110％,测定结果的相对标准偏差为0．1％～3．6％（n=5）。方法适合于水中16种多环芳烃的测定。     

反相高效液相色谱法测定狼把草中的木犀草素

用反相高效液相色谱法分离并测定了狼把草中的木犀草素，建立了该中药中木犀草素分离、测定的色谱方法。色谱条件：ＯＤＳ柱，甲醇－水－乙酸（７０：３０：０．４Ｖ／Ｖ）为流动相，紫外检测波长２５４ｎｍ。为扩大中药及植物中木犀草素药物资源的开发提供了简便、灵敏、准确的测定方法     

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.     

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.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.