水杨酸钠紫外分光光度法测定烟草中的总氮

建立水杨酸钠紫外分光光度法测定烟草中总氮含量的方法。烟草样品经硫酸铜–硫酸钾–浓硫酸消化,用水杨酸钠–二氯异氰尿酸钠显色后用紫外分光光度计检测,并对波长、显色剂用量和反应时间等实验条件进行了优化。总氮的质量浓度在5~60 mg/L范围内与其吸光度呈良好的线性关系,线性相关系数为0.998 8,方法的检出限为0.14 mg/L。样品分析结果的相对标准偏差为3.22%(n=6),样品加标回收率为99.30%~101.62%。该方法具有较高的精密度和准确度,尤其适用于样品量少时对烟草中总氮的测定。     

Br?nsted酸性离子液体催化缩醛化反应合成聚甲氧基二烷基醚

聚甲氧基二烷基醚(RO(CH2O)nR)具有高的十六烷值(CN)和含氧量,能显著改善柴油的燃烧特性,有效提高热效率,大幅减少碳烟和NOx排放,被认为是一种优良的环保型燃油组分.随着–R基碳链的增长,CN值、热值和闪点逐渐增大,密度和冷凝点逐渐降低.同时,该类化合物具有优异的溶解及渗透性能,能与许多有机溶剂互溶,低毒,可以用作溶剂或颜料分散剂.近年来,聚甲氧基二甲基醚(CH3O(CH2O)nCH3,PODEn,DMMn)的制备及应用研究受到广泛关注,而对封端基团(–R)碳数大于1的多醚类化合物的研究鲜有文献报道.本文以Br?nsted酸性离子液体为催化剂,对甲醛和二乙氧基甲烷或脂肪醇(碳数 ≥2)缩醛化反应制备聚甲氧基二烷基醚的反应性能进行了研究,考察了离子液体结构和酸性对其催化性能的影响.结果表明,–SO3H功能化的离子液体[MIMBs]HSO4在催化三聚甲醛与二乙氧基甲烷的缩醛化反应中表现出最好的催化活性.考察了催化剂用量、原料配比、反应温度、反应压力和反应时间等因素对反应性能的影响,并得到了最佳反应条件,在n([MIMBs]HSO4):n(DEM1):n(HCHO)=1:80:80,140°C下反应4 h,甲醛转化率达到了92.6%,DEM2–8选择性为95.1%.考察了不同甲醛源(三聚甲醛和多聚甲醛)与提供封端基团化合物(二乙氧基甲烷、乙醇、丙醇和丁醇)的缩醛化反应.结果发现,在反应过程中不生成水或不引入水的条件下,具有更高的反应转化率和产物选择性.分别采用静置分层和萃取实现了催化剂的分离与重复使用.推测反应机理认为,三聚甲醛首先在氢键作用下分解生成甲醛单体,甲醛和二乙氧基甲烷通过碳正离子反应机理实现了DEMn的链增长.     

2-取代芳基-4-丙酸乙酯基-1,5-苯并二氮卓衍生物的高效合成

以取代的芳香醛和乙酰丙酸乙酯为原料,通过克诺维纳盖尔(Knoevenagel)缩合、亲核加成、环合、脱水等过程,快速高效地合成了8种未见文献报道的2-芳基-4-丙酸乙酯基-1,5-苯并二氮杂卓化合物.通过₁H NMR、₁₃C NMR、IR、MS和单晶衍射确定了其目标产物结构,对合成目标化合物的反应条件进行了较详细的研究,并提出了可能的反应机理。     

搅拌萃取–分光光度法检测水环境中阴离子表面活性剂

建立搅拌萃取–分光光度法快速检测水环境中阴离子表面活性剂的含量。用三氯甲烷以800~1 200 r/min搅拌萃取水样与亚甲蓝溶液合成的活性物质,搅拌时间为2 min,静置分层后经脱脂棉过滤,待测。阴离子表面活性剂质量浓度在0.050~0.500 mg/L范围内与吸光度线性良好,相关系数大于0.999 0,方法检出限为0.010 mg/L。选择饮用水源水、农村地下水、湖泊水、城市河道水作为研究对象,平行检测结果的相对标准偏差(RSD)为1.9%~6.5%(n=6),加标回收率为91.3%~110%;对标准物质检测结果的相对误差为–2.3%~3.5%,满足实验室分析质量控制要求和现行地表水、地下水质量标准的评价要求。该方法与国标检测方法相比,在准确度、精密度、灵敏度、分析效率及试剂用量方面均有明显优势,具有推广应用价值。     

Synthesis and in vitro anticancer activity of pyrazolo[1,5-a]pyrimidines and pyrazolo[3,4-d][1,2,3]triazines

A novel series of pyrazolo[1,5-a]pyrimidines 14a–j and pyrazolo[1,5-a]quinazolines 18a, b were synthesized via condensation of 5-amino-1H-pyrazoles 10a, b with 3-(dimethylamino)-1-aryl-prop-2-en-1-ones 11a–e and 2-((dimethylamino)methylene)-5,5-dimethylcyclohexane-1,3-dione (15), respectively, in glacial acetic acid. Finally, treatment of 10a, b with sodium nitrite (NaNO₂) afforded pyrazolo[3,4-d]triazines 20a, b. Structures of compounds were confirmed by their spectral data. These compounds were screened for their in vitro cytotoxic activities against human cancer cell lines (HepG-2 and MCF-7) using 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The results reveal that, the compounds 14b and 14h were the most potent in comparison with doxorubicin. The structure–activity relationship was discussed.     

Simultaneous Spectrophotometric Determination of Imipramine Hydrochloride with Chlordiazepoxide and Nortriptyline Hydrochloride with Fluphenazine Hydrochloride

Spectrophotometry was used with multivariate calibration to simultaneously determine compounds in mixtures. Two antidepressant mixtures were investigated: imipramine hydrochloride and chlordiazepoxide and nortriptyline hydrochloride and fluphenazine hydrochloride. Considerable spectral overlap and large differences in component concentrations were challenges. Since this type of analysis is often performed using complex algorithms, a simple strategy was used here for the simultaneous determination of both mixture components by classical least squares, principal component regression, and partial least squares. Experimental design was used to select the optimum parameters including the wavelength range, sampling interval, software, and derivative order. Accuracy was enhanced by proper wavelength selection. In addition, derivatives of the raw spectra improved the selectivity. The standard deviation, deviation of mean recovery from 100%, and prediction ability of the models were used as the responses. In respect to these terms, first-order derivatization of the spectra and a sampling interval of 1?nm provided the best results. In particular, the low concentration compounds in the mixtures (chlordiazepoxide and fluphenazine) were determined more accurately with precision lower than 3%. The strategy was used for the quality control of pharmaceuticals containing the mixtures without chemical pretreatment.     

Two compounds constructed from Strandberg-type polyoxoanions,metals and organic ligands

Two new hybrid compounds, [Cu(1)(phen)(H₂O)][Cu(2)(phen)(H₂O)]([Cu(3)]_0.25(H₂O)][P₂Mo₅O₂₃]·3.75H₂O (1) and [Cu(en)₂]_1.5[P₂Mo₅O₂₃]₂·(enH₂)₃·2H₂O (2) (phen = 1,10-phenanthroline, en = ethylenediamine), have been hydrothermally synthesized and characterized by IR, UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), powder XRD analyses, TG analyses, cyclic voltammogram analyses, elemental analyses, and single crystal X-ray diffraction analyses. Single crystal X-ray diffraction analyses reveal that the two compounds have a 1-D chain structure formed by Strandberg-type POMs and TMCs with –A–B–C–B–A–B–C–B– linking mode, then further extend into a 2-D layer structure through π?π or hydrogen bond interactions.     

Synthesis,Crystal Structure,Fluorescent and Antioxidation Properties of Cerium(III) and Europium(III) Complexes with Bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine

Two aliphatic ether Schiff base lanthanide complexes (Ln = Eu, Ce) with bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine (Bod), were synthesized and characterized by physicochemical and spectroscopic methods. [Eu(Bod)(NO₃)₃] ( 1 ) is a discrete mononuclear species and [Ce(Bod)(NO₃)₃DMF]_∞ ( 2 ) exhibits an inorganic coordination polymer. In the two complexes, the metal ions both are ten‐coordinated and the geometric structure around the Ln^III atom can be described as distorted hexadecahedron. Under excitation at room temperature, the red shift in the fluorescence band of the ligand in the complexes compared with that of the free ligand can be attributed to coordination of the rare earth ions to the ligand. Moreover, the antioxidant activities of the two complexes were investigated. The results demonstrated that the complexes have better scavenging activity than both the ligand and the usual antioxidants on the hydroxyl and superoxide radicals.     

Visible‐Light‐Mediated Remote Aliphatic C−H Functionalizations through a 1,5‐Hydrogen Transfer Cascade

A redox‐neutral, light‐mediated functionalization of unactivated C(sp³)−H bonds via iminyl radicals is presented here. A 1,5‐H transfer followed by the functionalization of a C(sp²)−H bond takes place in aqueous media producing a variety of elaborated fused ketones. Mechanistic investigations have revealed 1,5‐H transfer as the reversible, rate‐determining step in this transformation. Divergent scaffolds are also accessible via C(sp³)−N bond formation upon a careful choice of the reaction additives.