溶剂萃取-GC-MS法分析4个品种风信子花挥发性成分

建立了风信子花挥发性成分的溶剂萃取-GC-MS的联用分析方法。从4个品种风信子花中共分离鉴定出挥发性成分65种,其中,以醇类和酯类化合物数量较多,合计占了各品种总数量50%以上;以萜、醇和酯三类含量占比较多,均超过各品种总香气成分70%。4个品种的共有成分有7个,分别为苯甲醇、苯乙醇、苯甲醛、乙酸正丁酯、丁酸乙酯、苯甲酸苄酯和1-苯基-1-甲氧基甲酮肟,在各品种中所占总含量分别为39.3%、12.4%、29.1%和76.1%。4个品种所占主要成分各异,表现出明显不同的“骨架”香气特征。     

顶空固相微萃取-气相色谱-质谱法分析芝麻香精的挥发性成分

采用顶空固相微萃取-气相色谱-质谱法分离和鉴定芝麻香精中挥发性成分,用归一化法测定其相对含量。为使固相微萃取达到更高的效率,选用50/30μm DVB-CAR-PDMS的固相萃取头,萃取温度及时间为60℃和1h。两种芝麻香精中分别鉴定出31和28种香气成分,其中含量较高的几类物质分别为吡嗪类、呋喃类、吡啶类、酮类和酚类物质。1号香精中的主要香气化合物为:1,6-二氢-咪唑并[4,5-d]咪唑、甲基吡嗪、3,5-二甲基苯酚、糠醛、2,6-二甲基-4-氨基吡啶和5-甲基-2-呋喃甲醛。2号香精中的主要香气化合物为:2,3-二甲基吡嗪、2-糠酸糠酯、4-氨基吡啶、3,5-二甲基苯酚、乙酰基吡嗪和糠醛。     

GC-O-MS法对酒花中香气活性成分的分析

采用顶空固相微萃取气相色谱-嗅闻-质谱((HS-SPME-GC-O-MS)联用的方法研究酒花中的香气化合物的组成和风味,并与传统的同时蒸馏萃取、水蒸气蒸馏方法进行比较,定性采用质谱谱库检索结合保留指数进行验证。结果表明:3种方法测得的1号酒花中的香气活性成分存在较大的差异,HS-SPME法最为适合,该法共鉴定出71种成分,占总峰面积质量分数的97.93%,以月桂烯、β-石竹烯为主要成分的萜烯类化合物共22种,其质量分数达88.73%,醇类及酯类质量分数分别为1.98%,3.42%。采用该方法对3个不同的酒花品种定性并嗅闻,能够嗅闻到的香气活性成分共计34种,包括碳氢化合物(包括萜烯)类7种,醇(酚)类11种,酯类10种,酮类2种,未知化合物4种。嗅闻结果表明,在1号、2号、3号3种酒花中分别嗅闻到了26,23,16种香气物质,其中重要的香气活性成分为β-香茅醇、β-石竹烯、里那醇、香叶醇、α-萜品醇、β-香茅醇、橙花醇、橙花椒醇、香叶酸甲酯、辛酸甲酯、乙酸香叶酯等。     

固相微萃取-气相色谱-质谱测定杨梅香气

对利用固相微萃取-气相色谱-质谱联用仪分析杨梅果汁香气成分过程中的萃取及色谱质谱条件等关键因素进行了研究.通过优化条件,确定最佳萃取条件为:8 mL果汁加入1 g NaCl,50/30 μm的DVB/CAR/PDMS纤维头在50 ℃下萃取30 min.气质分析时,采用小直径衬管,并控制合适的质谱条件,可提高痕量组分响应及匹配度.通过面积归一法,确定杨梅香气主要成分为:4种烯类物质,约占62.59%;8种醇类物质,约12.68%;2种酯类,约0.89%.     

固相微萃取气质联用分析茉莉花的香气成分

利用顶空固相微萃取技术,采用气质联用仪分析茉莉花的香气成分,在弱极性和极性毛细管色谱柱条件下,分别用PDMS、PDMS/DVB、PA三种萃取头富集香气,分离出100多种香气成分,鉴定出含量大于0.1%的55种组分,占香气成分的97%,三种萃取头所得主成分完全一致,均为芳樟醇、乙酸苄酯、反式-金合欢烯、顺式-苯甲酸-3-己烯酯和吲哚。     

蛇龙珠干红葡萄酒香气成分的GC-MS分析

研究宁夏贺兰山东麓地区蛇龙珠(Cabemet Gemischt)干红葡萄酒香气的化学成分,采用溶液萃取法提取蛇龙珠干红葡萄酒中的香气成分;用气相色谱一质谱进行分离测定,结合计算机检索技术对分离化合物进行鉴定,应用TIC峰面积归一法测定各成分的相对含量;分离出32个峰,鉴定出29个香气化学成分,共占其色谱流出组分总量的98．06％;其中相对含量以3-甲基丁醇(47．97％)、丁二酸二乙酯(16．49％)、苯乙醇(10．33％)、2-羟基丙酸乙酯(6．41％)、2-甲基丙醇(3．51％)、二氢化-2[3氢]-呋喃酮(2．07％)、2,3-丁二醇(1．93％)、四氢化2-甲基噻吩(1．68％)、乙酸乙酯(1．21％)、己醇(0．95％)等成分为主。     

花生微波烘烤香气成分分析方法的建立与应用

建立了烤制花生香气成分分析的顶空固相微萃取/气相色谱-质谱(HS SPME/GC-MS)分析方法。优化的实验条件:HP-5色谱柱,萃取平衡温度80℃,萃取时间40 min,解析时间5 min。采用该方法对四粒红、大白沙、鲁花3种花生进行微波炉焙烤后产生的挥发性香气成分进行分析,共鉴定出29种成分,其中主要包括杂环类化合物9种,醛类化合物7种,醇类化合物3种,烯类化合物3种,酚类化合物2种,酯类化合物3种,其他化合物2种。根据上述风味物质对花生香味的贡献大小,选择7种主要特征香气成分2,5-二甲基吡嗪、2-乙基-3,5(6)-二甲基吡嗪、2-乙基-6-甲基吡嗪、2-戊基呋喃、2,3-二氢苯并呋喃、苯甲醛和苯乙醛进行定量分析,其标准曲线相关系数均超过0.997,标准物质的加标回收率为85%~101%,RSD不大于6.9%,检出限为0.63~13.4μg/L。比较了不同花生品种的香气差异,并通过分析不良风味成分苯乙醛的含量,发现以大白沙花生的特征香气浓度最高,苯乙醛含量最低,更适宜利用微波烘焙技术生产咸干花生食品。     

气相色谱-质谱对天然酿造酱油与配制酱油香气成分的分析比较

利用蒸馏萃取/气相色谱-质谱(SDE/GC-MS)方法对酱油香气成分进行了分析,在4种不同工艺生产的酱油中共鉴定出51种化学成分,其中醇类12种、酚类5种、醛酮8种、酸类6种、酯类7种、杂环化合物类13种,同时发现,3种酿造酱油中的共有成分为35种.不同工艺生产的酿造酱油中醇、酚、醛酮、酯类物质的种类均比配制酱油多1倍以上,酸类物质的总含量也远大于配制酱油,但配制酱油的杂环类风味物质比较丰富,主要为体现烤香风味的吡嗪类化合物.乙醇、2-甲基丙醇、3-己醇、3-甲硫基丙醇、苯乙醇、乙烯基-2-甲氧基-苯酚、4-乙基-苯酚、α-亚乙基-苯乙醛、香草醛、2-羟基丙酸乙酯、乙酸乙酯、乙酸苯甲酯、亚油酸乙酯、5-甲基糠醇、3-苯基呋喃为酿造酱油的特有成分.构成酱油特征香气成分的4-乙基愈创木酚、糠醇、糠醛等物质的含量在配制酱油中也相对较少.这正是酿造酱油与配制酱油风味不同的原因之一.该文研究结果验证了生产酿造酱油时不同原料不同工艺会对风味物质产生影响.     

干黄芪中挥发性成分的提取与分析

为了确定干黄芪的特征香气成分,采用同时蒸馏萃取法对干黄芪中的挥发性成分进行提取,并考察了原料用量、浸泡时间和提取时间三个因素对结果的影响。在较优条件下对干黄芪中的挥发性成分进行提取,提取物通过GC-MS分析,结合计算保留指数和NIST11谱库检索,共鉴定出65种挥发性成分,其中包括醛类20种、醇类9种、烃类7种、酚类5种、酯类5种、杂环类5种、酮类4种、酸类2种、其他类8种。其中正己醛、2-戊基呋喃、丁香酚、正己醇、1-辛烯-3-醇、糠醛等挥发性成分对干黄芪的特征香气贡献较大。     

同时蒸馏萃取-气相色谱/质谱法分析烟草中挥发性成分

本文对云南12种烟叶中挥发性成分进行提取分离,气相色谱/质谱测定.系统地对同时蒸馏萃取条件和色谱分离条件进行优化,结合谱库检索和匹配度定性方法鉴定149种化合物,并对其中的35种重要香气成分进行了定量分析,包括酮类7种、醇类6种、烯烃类4种、烟碱类3种、烷烃类2种、醛类2种、酯类2种、呋喃类2种等.该方法具有81.09％～97.45％的高回收率.结果表明,同时蒸馏萃取集采样、萃取、浓缩于一体,操作简单快速,适合于烟草中挥发性成分的提取,结合气相色谱/质谱联用仪(GC-MS)分离测定,能准确对挥发性成分进行定性和定量分析.     

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.     

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.     

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.     

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.     

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.     

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.