多组分烟用香精定量分析方法的研究进展

综述了近年来烟用香精、香料各组分化合物的定量分析方法的研究进展。面积归一化法、内标法、外标法和标准加入法等常用色谱定量分析方法主要用于烟用香精、香料中目标化合物或单个组分的测定;多标定量法、特征峰-内标定量法和多元校正法能深入剖析烟用香精复杂体系中各组分含量(引用文献48篇)。     

复杂香精配方的化学组成解析及香韵识别

结合气相色谱-质谱(GC-MS)分析结果和"烟用香精香料智能辅助调香系统"对复杂香精配方的化学组成进行解析,共解析出14种单体、2种精油。对精油类香料采用混合物加标法判断其是否存在于香精中,同时结合香原料的香韵分析进一步确定复杂香精的配方,香精的主体香韵是花香韵、果香韵和甜香韵。解析结果与调香师的品评结果一致。     

固相微萃取-气相色谱/质谱法建立烟用香精指纹图谱

采用固相微萃取法(SPME)对6批次的烟用HMT-4香精成分进行提取,GC/MS对其进行分析,建立了该香精的GC/MS指纹图谱的研究方法。通过参兑实验考察了色谱指纹图谱用于香精质量控制的可行性。结果表明:SPME法具有操作简便、快速、节能、萃取效率高等特点,适合于烟用香精成分的提取。6批次的HMT-4香精的指纹图谱稳定性好,相似度高,具有很强的特征性和唯一性。通过参兑实验发现色谱指纹图谱能全面、综合、准确地反映烟用香精的质量情况,可以成为烟用香精质量控制的有效手段。     

复杂烟用香精定量分析方法

采用色谱指纹图谱技术,对成品香精中各香料组分进行定量分析。首先,在对复杂烟用香精准确定性的基础上,确定各种香原料的特有组分,并在香精和香料中同时加入相同选定内标,通过已知质量的香料特征物的含量与香精中各香料的特征组分之比推出香精中各香料的含量。此定量方法简单快捷,实现了只用一种内标物定量分析出复杂香精中所有组分含量。分析结果准确可靠,为复杂香精配方进行深入的研究提供了可靠方法,提高了调香和仿香研究的工作效率,并为自主创香打下了基础。     

全二维气相色谱/飞行时间质谱用于烟用香精化学组分的分析

采用全二维气相色谱/飞行时间质谱(GC×GC/TOFMS),以较长的极性柱DB-WAX(60 m×0.25 mm×0.25μm)作为第一柱,较短的中等极性柱DB-1701(3 m×0.1 mm,0.4μm)作为第二柱,对一种国产香烟中常用的烟用香精进行了分析,共鉴定出相似度和反相似度分别大于800和900的化合物有84种(在相同条件下,GC/MS鉴定出的组分数仅为21种)。在与GC×GC/TOFMS相同的分析条件下,利用多内标定量法,用GC-GC/氢火焰离子化检测器(FID)进一步对这些组分进行了准确定量。实验结果很好地解释了该香精的致香机理。     

烟用香精的气相色谱法质量控制研究

采用配有氢焰检测器或催燃检测器的气相色谱仪,对烟用香精进行了快速分析。方法操作简便,结果可靠,可作为烟用香精原料、产品质量监控的有效手段。     

烟用香精的GC-MS指纹图谱

在卷烟生产中,烟用香精对卷烟的风格起着决定作用,所以稳定的烟用香精质量对卷烟内在品质的控制非常重要。目前,烟用香精的质量控制以物理指标方法为主,对质量的变化反映不显著,给质量控制带来困难。作者采用气相色谱一质谱(GC-MS)测定烟用香精的成分,建立其GC-MS指纹图,既有定量信息又有定性信息,为控制烟用香精的质量提供科学依据。     

烟用香精香料的固相微萃取-气相色谱指纹图谱及系统聚类分析

建立了1115烟用香精香料的气相色谱指纹图谱。选择65μm的PDMS/DVB作为萃取头的涂层,萃取温度及萃取时间分别为70℃和45min。用TEKNOKROMA TBR-5石英毛细管柱分离,氢火焰离子化检测器检测。应用所提出的方法分析了9个不同批次的1115烟用香精香料样品,结合系统聚类分析法区分了不同批次的样品指纹图谱,并通过掺兑试验进一步验证了方法用于烟用香精质量控制的可行性。     

基于GC-MS和计算机智能系统的烟草香精剖析及复配方法初探

通过GC-MS分析方法以及基于化学计量学建立的"烟用香精香料智能辅助调香系统"对复杂烟用香精进行定性定量解析,确定了香精的化学组成,并结合调香经验知识复配香精。从化学组成及气味特征两个方面对复配香精进行考察,结果表明,复配香精与原香精的色谱指纹图谱相似度达到97.8%,经专业调香小组品析,其气味特征与原香精基本一致。该工作综合仪器分析手段、化学计量学方法以及调香经验知识,为烟草香精的剖析和复配研究提供了一种思路。     

气相色谱-质谱联用法测定烟用香精成分——烟草用香精前处理方法比较

采用同时蒸馏萃取(SDE)、超声辅助液液萃取(ULLE)和固相微萃取(SPME)3种前处理方法提取HMT-3烟用香精成分,用气相色谱-质谱联用法(GC-MS)进行分析.对3种萃取方法鉴定出的组分作出比较,考察了方法的各自特点.选取了15种烟用香精为代表,分别采用3种萃取方法对不同类型的烟用香精进行提取.结果表明:ULLE操作简便、快速、节能、萃取效率高;SDE法和ULLE法的重现性明显好于SPME法,适合于香精的定量分析,而SPME有较高的灵敏度,更适合香精的定性分析.根据定性和定量的需要、方法的适用性和香精的物理状态,应选取不同的提取方法,从而能够快速、准确地获得样品信息.     

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.