热裂解-气相色谱-质谱法分析烟用咖啡颗粒热裂解特性

利用热裂解-气相色谱-质谱联用分析烟用咖啡颗粒的热裂解特性。分别于150、200、250、300、350℃对烟用咖啡颗粒进行热裂解分析，同时针对不同水分含量和粒径的咖啡颗粒在同一温度下进行热裂解成分分析。结果显示，随着温度的升高，热裂解产物逐渐增多，释放物质的种类逐渐也逐渐增多，在250℃时咖啡颗粒生成关键致香成分占比较高。不同水分含量和粒径的咖啡颗粒在250℃裂解时，水分越高，裂解产物中烟碱含量占比越高，烟气越充足；粒径越小，裂解产物中咖啡因和烟碱的总量越大，香气质量也越高。该试验为咖啡颗粒在卷烟中应用时的温度设计和香气品质改善提供理论依据。     

基于LC-MS/MS的咖啡酰奎宁酸异构体鉴别方法研究

该文对单咖啡酰奎宁酸和二咖啡酰奎宁酸的位置异构体分别进行液相色谱分析和不同碰撞能下的二级质谱分析,并对其质谱裂解规律进行了研究。结果发现,单咖啡酰奎宁酸的母离子377和子离子163在不同碰撞能下其强度发生显著变化,通过377/163的强度比值可区分其位置异构体。377/163比值大小依次为3-O-咖啡酰奎宁酸、4-O-咖啡酰奎宁酸、5-O-咖啡酰奎宁酸。二咖啡酰奎宁酸的母离子539和子离子377、163在不同碰撞能下其强度发生显著变化,通过539/377、377/163的强度比值可区分其位置异构体。539/377比值大小依次为4,5-O-二咖啡酰奎宁酸、3,4-O-二咖啡酰奎宁酸、3,5-O-二咖啡酰奎宁酸。377/163比值大小依次为3,5-O-二咖啡酰奎宁酸、4,5-O-二咖啡酰奎宁酸、3,4-O-二咖啡酰奎宁酸。基于Agilent Poroshell 120 SB-Aq C₁₈色谱柱,不同梯度下咖啡酰奎宁酸位置异构体的洗脱顺序均为5-O-咖啡酰奎宁酸、4-O-咖啡酰奎宁酸、3-O-咖啡酰奎宁酸、3,4-O-二咖啡酰奎宁酸、3,5-O-二咖啡酰奎宁酸和4,5-...     

乌龙茶新品种-乌木炎中香气成分的气相色谱/质谱分析

1 引言 乌木炎是近年来以大叶乌为母本,嫁接黄金桂后培育出来的一个新品种,乌木炎在外观、汤色、滋味及香气等方面均有其独特的风格.茶叶香气是构成茶叶品质的主要因子,关于乌木炎的香气成分未见有研究报道.本文采用气相色谱/质谱对乌木炎的香气成分进行了分析,并从感官评审和香气成分两个方面初步探讨了乌木炎与其嫁接源大叶乌和黄金桂之间的相关性.     

四川乌龙茶与福建武夷水仙茶香气成分的比较研究

茶叶的消费遍及全球。茶叶已成为人们喜爱的饮料,一个重要原因是它具有温和与优异的香气。乌龙茶是我国著名的半发酵茶,为市场上紧俏商品,其产品重视品种特征,成茶要有一定火候。红茶和绿茶香气成分在国外有较多研究,乌龙茶香气成分近     

喷墨打印中“咖啡环”效应的调控及应用

喷墨打印是一种将功能材料进行图案化沉积的手段,具有方法简便、成本低廉、灵活快速等优点,成为了最具前景的图案化方法之一,在功能器件研究应用领域受到了广泛关注。"咖啡环"效应是喷墨打印过程中一种常见的现象,它会导致功能材料的不均匀沉积,影响打印图案的分辨率以及所制备功能器件的性能。因此,"咖啡环"效应的研究对于喷墨打印图案精度及功能器件性能极为重要。本文综述了近年来液滴蒸发过程中"咖啡环"效应的研究进展,阐述了"咖啡环"效应的产生机理及抑制"咖啡环"效应的方法,并进一步介绍了抑制或利用"咖啡环"效应在喷墨打印制备高性能器件,如高质量光子晶体图案、高灵敏度传感器、半导体薄膜、透明导电膜、短沟道晶体管等方面的应用。最后,探讨了目前"咖啡环"效应在喷墨打印应用中仍需解决的问题,展望了调控喷墨打印过程中"咖啡环"效应与纳米材料相结合的广阔研究应用空间。这些工作将会对功能材料图案化、高性能器件制备及3D打印等具有重要意义。     

用乙烯与四氯化碳合成巨环内酯和含氧内酯

在环上含有13—17个、碳原子的巨环内酯,不仅具有极细腻而独特的麝香香气,更重要的是其定香功效(fixative power),这就是说能使香精的香气持久,在整个挥发过程中香气始终如一,并且能调和整个香精配方使其香气高尚而圆润,因此引起了香料业很大的兴趣。但直到目前为止,由于还没有能够用价廉而易于获得的原料来合成的简易方法,所以这些珍贵香料都是在极其小规模地进行生产。     

国家咖啡检测重点实验室在普洱开建

正从云南省出入境检验检疫局获悉,经过地方政府和检验检疫局积极筹备,国家咖啡检测重点实验室(普洱)在普洱市正式开工建设。国家咖啡检测重点实验室(普洱)建成后,将填补我国咖啡产品专业实验室的空白,为普洱咖啡产业检验检疫、仲     

辛醛VC缩醛的合成及其在茶籽油中的抗氧化性能

缩醛类化合物由于保持了原来醛类化合物所具有的珍贵香气,且留香持久,香气类型多,在调香中有很高的使用价值[1,2]。辛醛有很强的水果香味,在极稀时有令人愉快的甜橙香气,是我国GB2760-86规定暂时允许使用的食用香料,主要用于饮料、冰淇淋、糖果、面包中以及柑橘类香料的调合[3]     

气质联用法对比分析微波辅助裂解前后烟叶中主要香气物质的含量

使用微波辅助烟叶裂解模拟烟叶燃吸时的裂解过程,并利用同时蒸馏萃取装置提取微波辅助裂解前后烟叶中的主要香气成分,采用气相色谱.质谱联用法对微波裂解前后烟叶中的香气成分进行对比分析.研究表明经过微波辅助裂解后,烟叶中的大部分香气成分均有了较大的提高,尤其是与烟叶香气质量密切相关的类胡萝卜素降解产物和棕色化产物含量提高明显,烟叶裂解产生的致香成分的含量信息能够更科学、更合理的反映烟叶的香气质量,可以以此含量为标准来评价烟叶香气质量.     

中国不同产区赤霞珠干红葡萄酒香气成分数据的可视化分析

可视化技术被引入葡萄酒香气成分数据的分析,以达到鉴别区分不同产区葡萄酒的目的。葡萄酒分析样品是2005年赤霞珠干红葡萄酒产品。5个产区是河北昌黎、新疆玛纳斯、云南弥勒、宁夏贺兰山东麓和河北沙城。香气成分用二氯甲烷连续萃取,有机相真空浓缩之后进行GC-MS分析检测。共鉴定并半定量分析出5个产区赤霞珠干红葡萄酒中68种香气成分,对原始色谱分析数据进行标准归一化处理,将信息映射到[0,1]之间的灰度图空间,然后根据数据可视化原理,用Vc 构建含多种香气成分信息的二维灰度图,直观表征不同产地赤霞珠干红葡萄酒的香气成分信息。研究结果是一种反映葡萄酒化学信息的条形码技术,该技术转换葡萄酒香气成分色谱数据之后得到二维灰度图,能够良好区分不同产区的赤霞珠干红葡萄酒。     

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.     

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.