顶空-气相色谱-质谱联用分析桂花和叶中挥发性成分

采用谱库检索结合准确质量测定、保留指数、串联质谱技术的多维定性分析策略鉴定化合物, 能够提高定性分析的效率和准确性. 运用顶空-气相色谱-四极质谱、顶空-气相色谱-飞行时间质谱以及顶空-气相色谱-串联质谱联用技术对桂花样品进行了分析检测, 并采用多维定性分析思路对检出的挥发性成分进行了鉴定. 结果共确认出47种挥发性成分, 其中单萜类和倍半萜类化合物为主要组分. 该定性分析策略准确可靠, 可以广泛应用于复杂样品挥发性成分的定性分析中.     

自动化静态顶空-气相色谱-质谱对天然香精中挥发性化学成分的快速分析

运用静态顶空-毛细管气相色谱-质谱法对天然香精中挥发性化学成分进行了分析，采用质谱和保留指数检索结合的方法对香精中挥发性成分进行定性分析；对香精顶空分析条件进行了优化，在香精样品中加入适量饱和NaCI溶液，显著地提高了低极性挥发性组分的分析灵敏度；从该香精中检出了68个化合物，将峰面积归一化结果大于0．1％的60种挥发性成分进行了定性分析，并通过保留指数分析对其中45种化合物进行了确认；分析结果表明：香精中含有萜类(30．3％)、萜类衍生物(11．7％)、酚醚类(17．0％)、脂肪酸酯(20．9％)和一些小分子的缩醛类化合物(17．7％)，其中主要的挥发性成分为丁酸-1，1-二甲基-苯基乙酯(18．9％)、茴香脑(15．6％)、2-乙基-4-甲基-1，3-二氧戊环(9．8％)和β-石竹烯(7．7％)；对方法精密度进行考察．相对标准偏差(RSD)在0．62—9．36之间。     

液液萃取/气相色谱-质谱法结合自动解卷积-Kováts保留指数法定性分析电子烟液中的挥发性成分

基于液液萃取/气相色谱-质谱法结合自动解卷积-Kováts保留指数法,建立了电子烟液中挥发性成分的检测方法。对提取溶剂种类进行了优化,并依据烟液中香气成分的香气特征,分析果味和烟草味烟液的香韵构成和差异,确定不同果味烟液的特征香气成分。结果表明：(1)以乙醚为提取溶剂能减弱丙三醇对其他组分识别的干扰。(2)自动解卷积法能准确识别共流出组分和低含量组分;Kováts保留指数法提升了化合物识别的准确度。(3)在10种烟草味烟液中检出15种成分,以豆香、焦香香韵化合物为主;在21种果味烟液中检出80种成分,以果香、花香香韵化合物为主,确定了16类果味烟液的特征香气成分。通过随机验证实验,该方法可有效分辨不同果味类型的果味烟液和烟草味烟液。该方法样品用量少、前处理过程简单、样品分析用时短,能满足烟液中香气成分的检测需要,可为果味电子烟液的检验识别和监管提供参考。     

顶空固相微萃取-气相色谱-质谱法快速测定酱油中的挥发性风味成分

建立了一种快速简便地测定酱油中挥发性风味成分的顶空固相微萃取（HS-SPME）-气相色谱-质谱法(GC-MS)。以2-辛醇为内标,考察了萃取头、萃取时间、离子强度、萃取温度对酱油样品中挥发性风味物质萃取的影响。该方法对酱油中常见挥发性风味成分的测定有良好的重复性和回收率,对常见挥发性物质的定量比较准确。优化的HS-SPME条件为：涂层厚度为85 μm聚丙烯酸酯(PA)萃取纤维头,于45 ℃、NaCl质量浓度为250 g/L下对酱油样品顶空吸附40 min,于250 ℃下解吸2 min后进行GC-MS分离鉴定。酱油样品的分析结果表明,其挥发性风味物质中含量较高的是醇、酸、酯和酚类,此外还有一些羰基化合物和杂环化合物。     

珀金埃尔默TurboMatrix40顶空进样系统

正珀金埃尔默TurboMatrix40顶空进样系统-GC/MS空气在线监测解决方案具有以下特点:(1)满足美国、欧洲臭氧前体物等监测法规要求;(2)连续自动监测,远程监控同一色谱分析系统即可每小时获取同一样品的1套C2~C12化合物分析数据;(3)分离分析乙烷、乙烯和丙烯等低碳类化合物,能捕集样品中较宽范围的挥发性化合物;(4)稳定的保留时间,便于定性分析,定量结果     

顶空固相微萃取-气相色谱-质谱法分离鉴定金华火腿的挥发性风味物质

采用顶空固相微萃取法(HS-SPME)制备样品,利用气相色谱-质谱法（GC-MS）分离鉴定了金华火腿的挥发性风味物质。实验中筛选了固相微萃取纤维头,优化了固相微萃取的操作条件。用75 μm碳分子筛/聚二甲基硅氧烷（CAR-PDMS）纤维头,于60 ℃下对金华火腿样品顶空吸附40 min,于250　℃下解吸2 min,采用GC-MS对解吸物进行分离鉴定。金华火腿样品的分析结果表明,其挥发性风味物质中含量较高的是醛、酸和酮类化合物,还有一些含硫或杂环化合物。     

基于HS-GC-IMS分析爆珠香精挥发性风味成分差异

采用顶空气相色谱-离子迁移谱（HS-GC-IMS）技术,对不同清新玫瑰爆珠样品中的香精挥发性成分进行鉴定,并通过感官评价,结合主成分分析（PCA）、偏最小二乘判别分析（PLS-DA）、偏最小二乘回归法（PLSR）等多元统计方法识别判定不同样品的主要风味成分差异。结果表明：(1)感官评价显示该爆珠样品风格特征主要以花香、果香、木香为主,并辅以青香、甜香与酒香香韵,不同样品在花香、果香属性上呈显著差异（p<0.05）;(2)GC-IMS非靶向定性出样品中22种主要的挥发性风味组分,其中醇类8种、酯类3种、酮类3种、醛类3种、烯烃类3种、酸类1种、吡嗪类1种,且指纹图谱直观显示出挥发性较强的醇类、酯类等香气化合物在样品间差异明显;(3)PCA、PLS-DA能对不同样品进行有效区别,并筛选出10个特征差异组分（VIP>1）,PLSR得出样品感官差异主要与2-甲基丁酸乙酯、丁酸乙酯、环己酮、苯乙酮、辛醛、正丙醇和芳樟醇有关。该方法可有效区分不同清新玫瑰爆珠样品,其判定结果与感官评价结果一致,具有准确可靠、可视化强等特点,能够为烟用爆珠产品感官质量快速检验提供技术支持。     

固相萃取-气相色谱-质谱法分析电子烟烟液中的香味成分

为了检测电子烟烟液中的香味成分,建立了固相萃取-气相色谱质谱检测方法。利用Li Chrolut EN固相萃取柱富集香味成分,以二氯甲烷为洗脱剂,洗脱液用气相色谱串联质谱分析。方法能有效富集烟液中的香味物质,排除雾化剂(甘油、丙二醇)对香味成分的干扰;重复性较好,大部分化合物峰面积相对标准偏差小于10%。利用该方法分析了4种烟液样品,结果不同口味电子烟所含香味成分差别较大。     

气-质联用及感官气相色谱法测定轮胎中的挥发性异味物质

采用-顶空气相色谱-质谱联用法(GC-MS)结合感官气相色谱法(Sensory-GC)检测分析了轮胎中挥发性异味物质。对影响分析结果的主要条件进行了优化。GC-MS共定性出25种化合物,而Sensory-GC分析结果表明轮胎挥发性物质中呈现明显异味的物质共有17种,其中烃类物质有6种;酮类物质有3种;胺类物质有2种;醛类物质1种;杂环化合物1种;酚类化合物1种。另外还有3种找不到化合物与之匹配的未知物。通过频率检测法及AEDA法分析可知,叔丁胺、甲基异丁基甲酮、对二甲苯、苯甲醛、苯并噻唑、对叔丁基苯酚等对轮胎异味有较大的贡献,它们分别表现为氨臭味、樟脑气味、干草臭、杏仁味、橡胶味及焦臭味等。     

柠檬果茶中游离态和键合态挥发性成分分析

以柠檬果茶为研究对象,建立了顶空固相微萃取前处理结合气相色谱质谱联用技术测定其中挥发性化合物的分析方法。采用开水冲泡对样品进行提取,通过Amberlite XAD-2大孔吸附树脂对柠檬果茶中的糖苷类挥发性组分键合,分离游离态和键合态化合物,甲醇溶剂作为洗脱剂对键合态化合物进行洗脱,Almondsβ-D-葡萄糖苷酶对其酶解。使用气质联用对样品中游离态和键合态挥发性成分进行检测,其结果根据数据库匹配和对比文献保留时间定性,内标法进行定量。结果表明,柠檬果茶中含有游离态物质24种,键合态物质16种,主要为(+)-柠檬烯、1-辛醇、橙花醇、(-)-4-萜品醇、alpha-松油醇等。方法为花果茶干燥工艺提供参考。     

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%.     

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.     

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.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.