Chiral phosphine-catalyzed regio- and enantioselective allylic amination of Morita–Baylis–Hillman acetates

Enantioselective allylic substitution of Morita–Baylis–Hillman (MBH) acetates with phthalimide was realized in the presence of a novel l-proline-derived chiral trifunctional phosphine amide ligand to give the corresponding allylic amination adducts in good yields (70–95%) and in modest to good enantioselectivities (34–78% ee’s).     

Organocatalytic Asymmetric Friedel–Crafts Reaction of Sesamol with Isatins: Access to Biologically Relevant 3‐Aryl‐3‐hydroxy‐2‐oxindoles

The Friedel–Crafts reaction of electron‐rich phenols with isatins was developed by employing bifunctional thiourea–tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epiCDT‐ 3 a efficiently catalyzed the Friedel–Crafts‐type addition of phenols to isatin derivatives to provide 3‐aryl‐3‐hydroxy‐2‐oxindoles 7 and 9 in good yield (80–95 %) with good enantiomeric excess (83–94 %). Friedel–Crafts adduct 7 t was subjected to a copper(I)‐catalyzed azide–alkyne cycloaddition to obtain biologically important 3‐aryl‐3‐hydroxy‐2‐oxindole 11 in good enantiomeric excess and having a 1,2,3‐triazole moiety.     

铬天青S–盐酸氯丙嗪–溴化十六烷基三甲铵光度法测定水样中的铁

采用铁(Ⅲ)–铬天青S–盐酸氯丙嗪–溴化十六烷基三甲铵(CTMAB)四元配合物光度法测定水样中铁的含量。在pH 5.50的HAc–NaAc缓冲介质中,在铁(Ⅲ)–铬天青S–盐酸氯丙嗪显色反应中,加入CTMAB,四元配合物的表观摩尔吸光系数为9.85×10~4 L/(mol·cm),是三元配合物灵敏度的两倍。结果表明,配合物在657nm波长处有最大吸收,Fe(Ⅲ)的质量浓度在0~20μg/(25 mL)范围内与吸光度呈良好的线性关系,线性相关系数为0.999 6,方法的检出限为1.84×10~(–3) mg/L。样品加标回收率为97.3%~98.8%,测定结果的相对标准偏差为1.9%~3.2%(n=5)。该方法灵敏度高,精密度与准确度好,便于在实验室推广应用。     

Catalyst-free facile and efficient one-pot synthesis of densely functionalized pyrroles and α-amino ketones

An efficient catalyst-free one-pot three-component synthesis of penta-substituted pyrroles has been successfully developed. A variety of penta-substituted pyrroles were straightforwardly synthesized from good to excellent yields (78%–93%) by using easily accessible starting materials under mild conditions. This protocol also provided α-amino ketones in good yields (87%–98%) without column chromatography.     

免试剂离子色谱法测定污水处理厂出水中氟、氯、亚硝酸根、硫酸根、硝酸根离子的含量

应用离子色谱法测定污水处理厂出水中F^ F^-, CI^-, NO2^-, SO4^2-, NO3^-离子的含量,利用ICS-2000免试剂淋洗液发生器,通过调节淋洗液的浓度及流速,方便、快速地实现了5种离子的良好分离。同时建立了5种离子的分析方法,该法具有良好的线性、准确性和重现性,测定结果的相对标准偏差小于1％（n=6）,5种离子的回收率为97．7％-102．6％.对比了标准曲线法与单点矫正法在分析5种离子上的优缺点。     

快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺含量

以快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺的含量。土壤样品经ASE–350快速溶剂萃取仪萃取,萃取液用凝胶渗透色谱净化浓缩后,用全扫描模式(SCAN)采集气相色谱–质谱法测定土壤中的邻甲苯胺含量。该方法检出限为0.01 mg/kg,加标回收率为78.3%~95.5%,测定结果的相对标准偏差为2.35%~14.9%(n=6)。该方法具有分离效果好、灵敏度高、重现性好、前处理操作简便及纯化效果好等优点,可用于测定土壤中邻甲苯胺的含量。     

Asymmetric cross aldol addition of isatins with α,β-unsaturated ketones catalyzed by a bifunctional Brønsted acid–Brønsted base organocatalyst

The asymmetric cross-aldol reaction of isatins with α,β-unsaturated ketones has been developed under catalysis by a Cinchona alkaloid-derivated bifunctional Brønsted acid–Brønsted base catalyst, affording the aldol adducts in moderate to good yields (18–98%) with moderate to good enantioselectivities (30–97%). The noncovalent organo-catalyzed asymmetric cross-aldol reaction displays a broad substrate scope and wide functional-group tolerability, albeit the electronic and steric properties of both reaction partners have considerable and regular effects on the reactivity and stereocontrol.     

Synthesis and Bioactivity of Benzothiazaphosphepines and Relevant Phosphonates as Antioxidant/Antidiabetic Agents

An efficient approach to a new series of benzothiazaphosphepines and their derived phosphonates in good yields (64–75%) was reported. The strategy relied on the reactions of the easily available 2-arylmethylene-aminobenzenethiols with different types of Wadsworth–Horner–Emmons (WHE) reagents in dimethylformamide (DMF)/lithium hydride (LiH) solution. All new compounds were bioscreened and showed, in vitro, moderate to good antioxidant and antidiabetic activities.     

ICP-AES法测定钢中的铈

建立了离子体发射光谱仪测定钢中铈元素的方法。为消除共存元素对铈分析游线的光谱干扰,选择Ce413．380nm作为分析线,铈含量在0．005％-0．50％之间工作曲线线性良好。对于含量范围在0．005％-0．10％的铈元素,回收率为85．6％-12．5％,测定结果的相对标准偏差小于9．74％（n=8）;对于含量范围在0．10％-0．50％的铈元素,回收率为99．5％-103．0％,测定结果的相对标准偏差小于3．52％（n=8）。该方法适宜钢中含量范围在O．005％-0．50％的铈元素的测定。     

电感耦合等离子体质谱法检测农作物土壤中的镉、锡、锰、锑、钒、钛、锶金属污染物残留

建立全自动石墨消解- 电感耦合等离子体质谱(ICP-MS)法检测农作物土壤中的镉、锡、锰、锑、钒、钛、锶金属污染物残留的分析方法.随机采集农作物土壤,取约200 g,置于烘箱中烘干,烘干后的样品用粉碎机粉碎,精密称取粉碎后的样品约0.25 g,置于聚四氟乙烯材质的消解罐内,按既定消解程序进行自动消解处理,得样品溶液,上...     

Palladium-catalyzed asymmetric allylic alkylation using chiral aminophosphine ligands

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate 18 with a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of new chiral aminophosphine ligands 1–5 in good yields with good enantioselectivities (up to 85% e.e.).     

吹扫捕集–气相色谱–质谱法测定地表水中5种硝基苯类化合物

对吹地表水中5种硝基苯类化合物进行吹扫捕集富集,解吸后用气相色谱-质谱联用法同时测定,内标法定量,加入硫酸钠提高方法的灵敏度,优化并验证检测方法。实验结果表明,使用Te Kmer-Dohrmann 3100型吹扫捕集仪,在吹扫温度为45℃、吹扫14 min的条件下测定水质中5种硝基苯类化合物,在0~60μg/L范围内线性关系良好,检出限为0.03~0.05μg/L,加标回收率为91.7%~95.9%,测定结果的相对标准偏差为1.00%~1.84%(n=7)。该方法操作简便、准确度高、重现性好,能够满足地表水中5种硝基苯类化合物的同时测定。     

Synthesis and characterization of polyarylates derived from 4,4′-dihydroxy-meta-terphenyl and aromatic diacid chlorides

Polyarylates derived from 4,4″-dihydroxy-meta-terphenyl (DHmTP) were prepared by the phase-transfer catalyzed, two-phase polycondensation with aromatic diacid chlorides. The resulting polymers were crystalline, solvent resistant, and produced brittle films. Copolymers with bisphenol-A were also synthesized using isophthaloyl diacid chloride. At low to moderate levels of DHmTP in the copolymers (25–75%), the materials had high glass transition temperatures (186–201°C), good solvent resistance, and gave tough, clear films. Terpolymers of DHmTP and BPA with 50:50 isophthaloyl and terphthaloyl diacid chloride were prepared with not much improvement over Ardel D-100®. All the DHmTP-polyarylates had good thermal stability (5% weight loss in air > 415–460°C) and had a high % char (20–48%). © 1994 John Wiley & Sons, Inc.     

Microwave assisted asymmetric Suzuki-Miyaura and Negishi cross-coupling reactions: synthesis of chiral binaphthalenes

Microwave assisted asymmetric Suzuki-Miyaura and Negishi enantioselective cross-coupling reactions are reported for the first time, and have been applied to the rapid synthesis of chiral sterically hindered binaphthalene derivatives in reasonable to excellent yields (65–96%) and fair to good enantioselectivities (43–70% ee).     

Pipette‐tip solid‐phase extraction using cetyltrimethylammonium bromide enhanced molybdenum disulfide nanosheets as an efficient adsorbent for the extraction of sulfonamides in environmental water samples

Surfactant cetyltrimethylammonium bromide enhanced molybdenum disulfide was used as an adsorbent in pipette‐tip solid‐phase extraction for the pretreatment of sulfonamides in environmental water samples. The factors affecting the extraction recoveries of the analytes, including the sample pH value, amount of sorbent, type and volume of eluent solution, and salt concentration were optimized. This pipette‐tip solid‐phase extraction method demonstrated good linearity (0.05–10.0 µg/L) with a coefficient of determination of 0.9984–0.9996, limit of detection (0.2–0.4 ng/L) and limit of quantitation (0.5–1.0 ng/L), good analyte recoveries (76–91), and acceptable limit of quantitation (<10%) under the optimized conditions. These results indicated that the proposed method was a good tool for monitoring sulfonamides in environmental water samples.     

Novel synthesis of aminoacetonitriles via the selective demethylation of quaternary ammonium salts

N-Methyl cyclic amines readily formed quaternary ammonium salts upon treatment with iodoacetonitrile in high yields (70–96%). The latter were selectively demethylated by heating in dimethylformamide to give aminoacetonitriles in moderate to good overall yields (36–69%).     

Palladium-catalyzed asymmetric allylic substitution using planar chiral hydrazone ligands

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (3) with a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of planar chiral phosphine-hydrazone ligands such as 2a in good yields with good enantioselectivities (up to 96% ee).     

Simultaneous quantitation of seven alkaloids in processed Fuzi decoction by rapid resolution liquid chromatography coupled with tandem mass spectrometry

A rapid analytical method based on rapid resolution LC coupled with MS/MS was first established to quantify seven alkaloids in processed Fuzi decoction. The chromatographic method was optimized to allow simultaneous analysis of all analytes in 5 min and demonstrated good linearity (r > 0.9995), repeatability (RSD < 4.36%), intra‐ and interday precisions (RSD < 5.07%) with good accuracies (97.76–105.08%) and good recovery (95.0–107.5%) of seven alkaloids, namely higenamine, benzoylhypaconine, benzoylmesaconine, benzoylaconine, aconitine, hypaconitine, and mesaconitine. The LODs for these markers were in the range of 2.30–17.00 pg/mL. Quantitative analysis of the seven alkaloids in Baifupian decoction and Heishunpian decoction showed that the content of the seven marker chemicals varied significantly and concluded that the quality of Fuzi was greatly affected by different processed methods. The developed method could be used as a rapid, sensitive, and reliable approach for assessment of the quality of processed Fuzi and related decoction.     

Modified knoevenagel condensations. Synthesis of (E)-3-alkenoic acids.

Condensation of aliphatic aldehydes with a three molar excess of malonic acid and 0.001 mole of piperidinium acetate in refluxing xylene, with continuous removal of the water formed, gave almost exclusively (E)-3-alkenoic acids, in good yield (60–85%) and of high stereochemical purity (95–99%).     

Polyimide‐coated magnetic nanoparticles as a sorbent in the solid‐phase extraction of polycyclic aromatic hydrocarbons in seawater samples

Magnetic polyimide poly(4,4′‐oxydiphenylene‐pyromellitimide) nanoparticles were successfully synthesized and developed for the solid‐phase extraction of polycyclic aromatic hydrocarbons in seawater samples. The aromatic rings of polyimide coating provided a good adsorption capacity (28.3–42.5 mg/g) for polycyclic aromatic hydrocarbons because of the π–π stacking interaction. The developed method was used as a simple, fast, and efficient extraction and preconcentration technique for the trace analysis of polycyclic aromatic hydrocarbons. The high chemical, physical and thermal stability, excellent reusability, and good magnetic properties are the merits of the sorbent. High preconcentration factors (41–63) were obtained. The sorbent was also characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, transmission electron microscopy, and vibrating sample magnetometry. After optimizing several appropriate extraction parameters, the results indicated that the extraction recoveries of polycyclic aromatic hydrocarbons were in the range of 61.6–94.7%, with relative standard deviations between 2.9 and 5.4%, the calibration graph was linear in the concentration range of 1–100 μg/L (r > 0.9991) with limit of detection in the range of 0.15–0.19 μg/L (n = 3). Seawater samples were analyzed as real samples and good recoveries (68.5–99.5%) were obtained at different spiked values.