全扫描-选择离子数据采集技术应用于烟草中生物碱的快速测定

建立了应用气相色谱-质谱(GC-MS)全扫描-选择离子监测(Scan-SIM)数据采集方式同时测定烟草中8种含量相差较大的生物碱的方法,采用Scan模式分析烟碱、降烟碱、新烟碱、去氢新烟碱,同时采用SIM模式分析麦斯明、二烯烟碱、2,3′-联吡啶、可铁宁。结果表明,烟草中各生物碱的回收率为94.8%～98.8%,5次测定的相对标准偏差均小于6%。该方法具有简单、快速、准确的特点,应用于烟草样品测定,结果令人满意。     

溶剂萃取-毛细管气相色谱法测定烟草中主要生物碱

报道了用毛细管柱气相色谱同时测定烟草中尼古丁、去甲基尼古丁、新烟碱和去氢新烟碱4种主要生物碱的方法。烟草样品经二氯甲烷／甲醇(V/V,3：1)溶剂萃取,过一次性滤膜,直接进样,经HP-5MS毛细管柱分离,氮磷检测器(NPD)检测。该方法简单,重现性好;4种生物碱相对标准偏差为1．5％～3．4％;加标回收率为93．6％～102．4％。     

加速溶剂萃取-气相色谱-串联质谱法检测烟草中生物碱

建立了气相色谱-串联质谱(GC-MS/MS)法同时测定烟草中烟碱、降烟碱、麦斯明、假木贼碱和新烟草碱等5种生物碱的分析方法。以甲醇和Na OH溶液混合溶剂作提取溶剂,样品经加速溶剂萃取(ASE)萃取后,利用GC-MS/M S的多反应监测模式(M RM)测定,内标法定量。5种生物碱的检出限在0.06~0.12μg/m L之间,加标回收率介于88.9%~106.8%,相对标准偏差(RSD)均小于6%。方法适用于批量烟草样品中生物碱的快速测定。     

气相色谱-三重四极杆串联质谱法同时测定烟草中8种生物碱

建立了气相色谱-三重四极杆串联质谱(GC-MS/MS)分析烟草中8种主要生物碱的方法。样品经10%NaOH溶液浸提,二氯甲烷超声萃取后,采用GC-MS/MS多反应监测(MRM)模式测定,内标法定量。8种生物碱的回收率为93.2%~99.0%,相对标准偏差为2.8%~6.7%。该方法简单快速、灵敏准确,适用于烟草样品中生物碱的快速测定。     

超高效液相色谱-串联质谱法快速分析烟叶中的8种生物碱

采用超高效液相色谱-串联质谱(UPLC-MS-MS)建立了快速分析烟叶中8种生物碱的分析方法。50 mg烟叶粉末样品经2 mL 6%氨水浸润后，以10 mL二氯甲烷超声提取20 min,有机相用N-丙基-乙二胺(PSA)净化后氮吹近干，再以乙腈超声复溶后用UPLC-MS-MS分析。烟叶中8种生物碱(烟碱、新烟碱、新烟草碱、降烟碱、二烯烟碱、2,3′-联吡啶、可替宁、麦斯明)的平均回收率在86.5%～102%之间，相对标准偏差(n=6)为2.1%～5.4%;方法对烟碱的检出限为0.45 mg/g,定量限为1.5 mg/g;对其余7种微量生物碱的检出限在0.15～0.6μg/g之间，定量限在0.5～2μg/g之间。本方法适用于烟叶中8种生物碱含量的快速测定。     

基于顶空固相微萃取-全二维气相飞行时间质谱快速检测烟草挥发性及半挥发性生物碱

通过正交试验设计与单因素试验设计相结合,建立了顶空固相微萃取-全二维气相飞行时间质谱快速分析烟草挥发性及半挥发性生物碱的方法。烟叶样品在70℃条件下平衡20 min,然后采用PDMS/DVB/CAR纤维头在顶空瓶中平衡15 min,最后在250℃进样口解析3 min效果最好。以喹啉为内标,分别对烟草中烟碱、麦斯明和二烯烟碱3种生物碱的挥发性成分进行定性定量分析,其方法的线性相关系数(r2)为0.9944~0.9992,检出限为0.60~150 pg,添加回收率为86.7%~98.3%,相对标准偏差为1.8%~4.2%。通过实际烟草样品检测表明,不同生物碱的挥发性与总量具有显著相关性。     

气相色谱法测定烟草浸膏中的烟碱

为准确测定烟草浸膏中烟碱含量,以2-甲基喹啉为内标建立了测定烟草浸膏中烟碱的气相色谱-氢火焰离子化法(GC-FID),并测定了5个烟草浸膏样品.结果表明,方法的回收率为95.00%~98.58%,检出限为0.27 mg/g,定量限为0.89 mg/g.所测烟草浸膏中烟碱的质量分数在19.66~54.97 mg/g之间.方法简单、灵敏、准确,适用于烟草浸膏中烟碱的测定.     

气相色谱法分析电子烟烟液中主要生物碱含量

建立了电子烟烟液中主要生物碱含量的气相色谱测定方法,并对19种品牌电子烟共计51种型号电子烟烟液进行含量分析。电子烟烟液经超声稀释提取后,直接进行气相色谱分析。采用HP-50+型毛细管色谱柱,氢火焰离子化检测器检测,内标法定量。结果表明:上述化合物在各自浓度范围内线性关系良好(R20.996),3个加标水平的平均回收率在97.1%~104.6%之间,相对标准偏差(RSD)小于4%,检出限为0.00037%~0.0011%。实际样品测试结果表明:电子烟烟液中烟碱含量在0~28.36mg/mL,生产厂商所标注烟碱浓度差异率为-136.56%~100.00%,微量生物碱含量范围为0~0.045mg/mL,所测定微量生物碱总含量与烟碱含量之比在0~3.50%。     

GC/MS-SIM测定烟草中的生物碱

为了同时分析烟草中的烟碱和微量生物碱,考察了提取剂、提取时间、料液比对生物碱提取率的影响,建立了烟草中主要生物碱GC/MS-SIM快速测定方法,并采用这种方法分析了云南不同品种烤烟(C3F)中的生物碱。结果表明:该方法前处理简单,分析时间短,重复性好。烟草中的烟碱、降烟碱、麦斯明、二烯烟碱、新烟碱、去氢新烟碱、2,3’-联吡啶、可替宁能够完全分离。因此GC/MS-SIM适合批量烟叶样品中生物碱的分析。     

气相色谱-质谱法测定主流烟气中的植物碱

采用气相色谱-质谱法测定主流烟气中的烟碱、降烟碱、麦斯明、假木贼碱和新烟草碱。捕集有总粒相物的剑桥滤片加入内标后,用50g·L-1氢氧化钠溶液将植物碱游离出来,经乙酸乙酯萃取后,在DB-35MS色谱柱上分离,采用选择离子扫描模式。5种植物碱的浓度与峰面积在一定范围内呈线性关系。烟碱的检出限(3S/N)为12μg·支-1,其他4种植物碱的检出限(3S/N)为0.30~2.5μg·支-1。5种植物碱的加标回收率在86.5%~108%之间,测定值的相对标准偏差(n=6)在1.7%~4.5%之间。     

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%.     

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.     

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.     

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.     

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.