咔唑-9-乙基氯甲酸酯柱前衍生胺类化合物高效液相色谱分离

采用一种新的氯甲酸酯类荧光衍生试剂咔唑-9-乙基氯甲酸酯进行柱前衍生胺类化合物并通过荧光检测的方法进行高效液相色谱(HPLC)分析。衍生物的荧光激发和发射波长为λcr／λcrs=293/365nm。色谱柱：Hypersil BDS C18柱，柱温：35℃；流速：l mL/min；流动相A为水/乙腈(20／80，V／V)，流动相B为乙腈/水(95／5，V／V)。衍生试剂用量(mol)是胺类化合物总量的3～4倍时，衍生化产率最大且恒定。该方法具有检测灵敏度高，衍生化反应简单、快速、不受样品基质盐分的干扰，尤其适合天然生物样品，食品及饲料中的胺类化合物的分析。     

荧光试剂柱前衍生高效液相色谱-荧光检测生物检材中的氟乙酸钠

建立了以4-溴甲基-7-甲氧基香豆素(BrMMC)为柱前荧光衍生试剂,反相高效液相色谱荧光检测(HPLC-FLD)生物检材中氟乙酸钠的分析方法。采用Hewlett Packard RP-18色谱柱,以甲醇-水(60/40,V/V)为流动相,流速1.0 mL/min,柱温26℃,荧光检测:eλx=319 nm,eλm=390 nm,进样量2μL。结果表明:该法在氟乙酸钠含量为0.1~20μg/mL范围内与其峰面积呈良好的线性关系,线性相关系数为0.9996,检出限(S/N=3)为5×10-10mol/mL,相对标准偏差(RSD)小于4%。本法用于中毒死亡者的血液样品及其它检材的测定,效果良好。     

高效液相色谱法测定大鼠给药盐酸氟西汀后脑渗析液中的5-羟色胺

建立了高效液相色谱柱前衍生化法测定大鼠腹腔注射(i.p.)给药盐酸氟西汀前后脑渗析液中5-羟色胺(5-HT)的浓度变化情况。在大鼠给药盐酸氟西汀前和给药后不同时间点取其脑渗析液,加入衍生化试剂反应后,以乙腈-20 mmol/L醋酸盐缓冲液(pH 5.0)(体积比为45∶55)（含20 mmol/L辛烷磺酸钠）作为流动相,在Hypersil C18色谱柱 (250 mm×2.0 mm,5 μm)上进行分离,荧光检测波长为λex=330 nm,λem=455 nm。5-HT在浓度为0.25～5.0 nmol/L 范围内线性关系良好(r=0.9991);5-HT的最低定量限为0.25 nmol/L。本法准确可靠、简便,适用于生物样品中5-HT的浓度测定。     

高效液相色谱荧光检测法测定药物中的氯乙酰氯

建立测定药物中氯乙酰氯含量的高效液相色谱–荧光检测方法。以吖啶酮乙酰肼为荧光标记试剂,对氯乙酰氯进行柱前衍生。在室温下反应15 min,衍生产率达到最大。衍生溶液在XDB–C18柱上,以水和乙腈为流动相进行分析,激发波长和发射波长分别为255 nm和429 nm。氯乙酰氯浓度在1~1 000 nmol/L范围内与色谱峰面积具有良好的线性关系,线性相关系数r=0.999 9。方法的检出限为0.35 nmol/L,仪器精密度和方法精密度分别为0.52%和0.67%(n=6)。样品加标回收率为92.5%~95.6%。该方法简单、准确,精密度良好,可用于测定药物中氯乙酰氯的残留量。     

动物组织中金霉素残留测定的高效液相色谱柱后衍生反应研究

建立了动物组织中金霉素残留测定的高效液相色谱柱后衍生法,研究了镁离子和草酸体系对金霉素荧光强度的影响。结果表明,镁离子浓度和草酸浓度为1∶1.2时,金霉素的荧光强度最强。动物组织样品以5%高氯酸提取,正己烷脱脂,C18净化,Hy-persil ODS C18(250×4.6 mm,5μm)分离,流动相为甲醇∶0.05 mol/L草酸=80∶20(V/V),流速为0.7 mL/min,柱后0.05 mol/L乙酸镁衍生,流速为0.1 mL/min,紫外检测器和荧光检测器同时测定,提高了金霉素残留定量灵敏度。紫外检测波长365nm,荧光检测波长eλx=360 nm,eλm=520 nm。     

荧光衍生中性糖的高效液相色谱分析

在HypersilODS2色谱柱上,利用新型荧光试剂1,2-苯并-3,4-二氢咔唑-9-乙基肼基甲酸酯(BCEC)作柱前衍生化试剂,采用梯度洗脱对5种中性糖荧光衍生物进行了优化分离.65℃下在乙腈溶剂中以冰乙酸作催化剂,衍生反应6.5h后获得稳定的荧光产物,衍生反应完全.激发和发射波长分别为λex=333nm,λem=390nm.线性回归系数均在0.999以上,检测限为24.3～62.1fmol.     

2-(11H-苯[a]咔唑)乙基氯甲酸酯柱前衍生化用于氨基酸的高效液相色谱分析

利用新型荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯(BCEC-Cl)作为柱前衍生化试剂,在HypersilBDS C18(200mm×4.6mm,5μm)反相色谱柱上,采用梯度洗脱对20种氨基酸衍生物进行了分离检测。在乙腈与Na2B4O7缓冲液中,室温下BCEC-Cl与氨基酸反应5min可实现完全衍生。检测的激发和发射波长分别为λex=279nm,λem=380nm。采用柱后质谱电喷雾离子源(ESI source)正离子模式,实现了水解牛血清白蛋白中氨基酸和油菜蜂花粉中氨基酸的定性定量检测。荧光定性检测的线性回归系数均大于0.9990,检出限为1.49~19.74fmol(S/N=3)。     

柱前衍生高效液相色谱法检测合成牛磺酸及其中间产物的含量

提出了柱前衍生高效液相色谱法检测工业合成牛磺酸及其中间产物2-氨基乙基硫酸酯.用2,4-二硝基氟苯作为衍生化试剂,以乙腈-水-磷酸缓冲溶液(pH=7)为流动相,在360nm处进行紫外检测.上述两种物质在C_(18)反相色谱柱上得到良好的分离,并进行了定量测定.     

HPLC-APCI-MS法分析测定白刺籽油中游离脂肪酸

利用荧光衍生试剂1,2-苯并-3,4-二氢咔唑-9-乙基对甲苯磺酸酯(BDETS)作为脂肪酸柱前衍生化试剂,采用梯度洗脱在Eclipse XDB-C8色谱柱上对游离脂肪酸(FFA)(油酸、亚油酸、软脂酸和硬脂酸)衍生物进行分离.利用柱后在线的串联质谱以大气压化学电离源(APCI)正离子模式实现了各组分的质谱定性.荧光检测的激发和发射波长分别为λex=333 nm,λem=390 nm.脂肪酸的线性回归系数大于0.9990,检出限为3.38～6.59 nmol/L.建立的方法具有良好的重现性.利用此方法对超临界CO2提取的唐古特白刺籽油中几种游离脂肪酸进行了分析.结果表明白刺籽油中含有大量的游离不饱和脂肪酸.     

化学衍生-高效液相色谱法测定硫氰酸根阴离子

以α-溴-2,3,4,5,6-五氟甲苯作柱前衍生试剂,经优化衍生和色谱条件,实现了用高效液相色谱法测定硫氰酸根离子。在ODS柱上,用甲醇-水(80:20)作流动相,于254nm检测,得到线性关系良好的工作曲线,最小检测限为4.7ng。分析了吸烟者唾液样品,回收率为93.7％～101.4％。     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.