顶空-箭形固相微萃取-气相色谱-质谱法测定水中松节油的含量北大核心CSCD

在顶空瓶中加入水样10.0 mL、氯化钠3 g和20.0 mg·L^(-1)内标溶液10.0μL,选择涂层为120μm二乙烯苯/聚二甲基硅氧烷的箭形固相微萃取头,于50℃萃取30 min,脱附的气体用DB-1毛细管色谱柱分离,质谱仪检测,内标法定量。结果显示:松节油的主要成分为α-蒎烯,还有少量莰烯、β-蒎烯和柠檬烯等;松节油标准曲线的线性范围为5.0~100.0μg·L^(-1),检出限(3.143s)为0.6μg·L^(-1);对空白样品进行加标回收试验,回收率为95.9%~98.0%,测定值的相对标准偏差(n=6)为3.7%~4.3%;方法用于实际样品分析,结果均未检出松节油。     

气相色谱-质谱技术分析红松松塔挥发性成分

采用水蒸气蒸馏法,对红松松塔挥发性成分进行提取和研究,最佳蒸馏时间5.5 h,挥发油提取率1.28%.利用气相色谱-质谱联用技术对提取的挥发油成分进行分析,共鉴定出32种化学成分,主要为单萜和倍半萜类化合物,其中相对含量较高的有α-蒎烯(44.258%)、D-柠檬烯(23.426%)、β-蒎烯(8.674%)、石竹烯(3.462%)、β-月桂烯(3.018%)等.研究结果表明红松松塔挥发油中富含α-蒎烯、D-柠檬烯、石竹烯等多种具有药理活性的成分.因此,红松松塔是一种具有较好前景的天然药用资源.     

固相微萃取结合气-质联用分析麻椒挥发性成分

以四川广元产的麻椒为原料,利用固相微萃取技术对麻椒中的挥发性成分进行提取,分别用装有HP-5ms和HP-INNOWAXms两种色谱柱的GC-MS进行分离与鉴定;采用质谱与保留指数进行定性,共鉴定出99种成分,其中烯烃类58种、醛类15种、醇类9种、酯类7种、酮类3种、其他烃类4种、其他化合物3种。采用面积归一化法确定了它们相对含量,含量较高的有芳樟醇、D-柠檬烯、β-崖柏烯、β-水芹烯、β-月桂烯、β-蒎烯、(-)-右旋吉玛烯、石竹烯、γ-萜品烯、3-崖柏烯、(Z)-β-罗勒烯、(1R)-(+)-α-蒎烯、(+)-3-蒈烯、(Z,Z,Z)-1,5,9,9四甲基-1,4,7环-十一碳三烯、萜品油烯。从鉴定出的挥发性成分的香气特征可知,烯烃类、醇类和醛类对麻椒的香气贡献较大。     

火炬松挥发物的固相微萃取-气相色谱/质谱法分析

采用固相微萃取(SPME)技术,结合气相色谱/质谱(GC-MS)分析了火炬松枝条和针叶中的挥发性化合物,共鉴定了30种化学成分。其中枝条中分离鉴定出21种挥发性成分。主要成分为α-蒎烯、β-蒎烯、β-月蒎烯、反式-石竹烯、β-杜松烯、大根叶烯-D;针叶中分离鉴定出24种挥发性成分,主要成分为α-蒎烯、β-蒎烯、β-月桂烯、β-水芹烯、异长叶烯、反式-石竹烯、α-律草烯、大根叶烯-D、双环吉马烯和双环榄香烯。     

分散固相萃取-气相色谱-质谱法测定地表水中的异味物质

研究了分散固相萃取-气相色谱质谱法测定地表水中土臭素、2-甲基异茨醇、β-环柠檬醛、β-紫罗兰酮、2,4,6-三氯苯甲醚、2-异丙基-3-甲氧基吡嗪、2-异丁基-3-甲氧基吡嗪的方法。确定最佳分散固相萃取条件,在优化试验条件下对异味物质的测定结果显示,该方法重现性好,精密度高,7种异味物质的质量浓度均在0.05~10.0μg·L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)在1~5ng·L-1之间。应用本方法对空白加标水样进行测定,回收率在81.6%~98.4%之间,测定值的相对标准偏差(n=5)在7.1%~14%之间。     

固相微萃取结合气-质联用分析侧柏叶中的挥发性成分

以产自河北的侧柏叶为原料,采用四种固相微萃取纤维对其中的挥发性成分进行提取,用气质联用进行分析,共分离出112种成分,采用质谱与保留指数进行定性,鉴定出87种成分(四种萃取纤维的提取物中都鉴定出的成分有59种),其中烯烃类51种(以单萜和倍半萜为主),烷烃类4种,芳香烃类3种,醇类18种,醛酮类3种,酯类4种,醚类3种,吡嗪类1种;另外采用质谱初步定性出12种。采用面积归一化法确定了它们的相对含量,含量较高的有(1R)-(+)-α-蒎烯、(+)-3-蒈烯、D-柠檬烯、β-水芹烯、δ-松油烯、β-榄香烯、石竹烯、顺式-罗汉柏烯、葎草烯、大根香叶烯D、δ-杜松烯、柏木脑等。对比所得结果可以发现,CAR/PDMS(85μm)的萃取纤维对侧柏叶中挥发性成分的提取效果较好。     

气相色谱-质谱技术分析红松松塔挥发性成分

采用水蒸气蒸馏法，对红松松塔挥发性成分进行提取和研究，最佳蒸馏时间5.5h，挥发油提取率1.28％。利用气相色谱-质谱联用技术对提取的挥发油成分进行分析，共鉴定出32种化学成分，主要为单萜和倍半萜类化合物，其中相对含量较高的有α-蒎烯（44．258％）、D-柠檬烯（23．426％）、β-蒎烯（8.674％）、有石竹烯（3.462％）、β-月桂烯（3.018％）等。研究结果表明红松松塔挥发油中富含α-蒎烯、D-柠檬烯、石竹烯等多种具有药理活性的成分。因此，红松松塔是一种具有较好前景的天然药用资源。     

固相微萃取/加速溶剂萃取-气相色谱-质谱法分析青山绿水茶叶的挥发性成分

采用固相微萃取(SPME)和加速溶剂萃取(ASE)两种前处理方法从青山绿水茶叶(也叫苦丁茶)中提取挥发性成分,用气相色谱-质谱法(GC-MS)定性。实验结果表明:两种前处理方法共检测出91种成分,SPME检出49种,ASE检出56种,共同组分14种。青山绿水茶叶的挥发性成分主要成分有β-月桂烯、3,3,5-三甲基-1,5-庚二烯、L-柠檬烯、α-罗勒烯、β-罗勒烯、β-蒎烯、2-甲基安息香醛和5-羟甲基糠醛等物质。这两种提取方法各具优势,共同应用可以起到取长补短的作用。     

离子液体萃取-分光光度法测定水中结晶紫

合成了离子液体六氟磷酸1-丁基-3-甲基-咪唑[Bmim][PF_6],并以其为萃取剂,对结晶紫进行萃取。实验考察了溶液pH值、离子液体用量、盐的加入量、温度、共存离子等因素对结晶紫萃取率的影响。结果表明,溶液酸度在pH 3.2~6.0,在10.00 mL水中,离子液体加入量为0.40 mL时,离子液体对结晶紫的萃取率最大。结晶紫的质量浓度在0.1~2.0μg·mL~(-1)范围内与吸光度呈线性关系,相关系数R=0.9923。方法的检出限为0.02μg·mL~(-1),平均回收率在93.0%~96.6%之间。     

新型1-(4-取代苯基)-3-[4-(4-氧香豆素基)苯基]硫脲衍生物的合成及其抑菌活性

以4-羟基香豆素为原料,经氯化、醚化和异硫氰酸化3步反应制得中间体——4-(4-异硫氰酸酯苯氧基)香豆素(3);3与取代芳香胺经加成反应合成了9个新型的1-(4-取代苯基)-3-[4-(4-氧香豆素基)苯基]硫脲衍生物(4a~4i),其结构经1H NMR,13C NMR,IR和MS(ESI)表征。采用浑浊度法测试了4的抑菌活性。结果表明:4a、4b、4e和4f抑制烟草青枯菌活性EC50值分别为112.02、121.39、88.72和86.90μg·mL~(-1),优于噻菌铜(130.25μg·mL~(-1));4a、4b、4e和4f抑制番茄青枯菌活性EC50值分别为107.89、110.69、82.43和82.48μg·mL~(-1),优于噻菌铜(123.94μg·mL~(-1))。     

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.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

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.     

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.