气相色谱-质谱法测定煤直接液化供氢溶剂中55种芳烃

煤直接液化供氢溶剂样品经固相萃取和不同溶剂洗脱而分离为饱和烃、芳烃和胶质等3种组分。将所得芳烃组分进行气相色谱分离,由于所用色谱柱为弱极性毛细管色谱柱,得到了按沸点从低到高的规律出峰的55种芳烃的总离子流色谱图。在此基础上,经NIST谱库检索与标准谱库对比,运用ASPEN PLUS中数据库进行沸点检索,并结合保留指数文献对比,最终识别了这55种芳烃并计算其在HP-5MS色谱柱上的保留指数。采用高分辨气相色谱-质谱联用仪对各化合物的结构式和相对分子质量进行测定。用面积归一化法进行定量,确定了此55种芳烃的相对含量,芳烃碳数分布主要集中在C10～C16,占已测定芳烃总量的92.20%;芳烃类型主要为环烷苯类,占46.87%,其次为二环烷苯类和苊类,分别占19.13%,10.67%。     

喷气燃料裂解产物中芳烃的全二维气相色谱-质谱分析

采用全二维气相色谱-质谱联用仪(GC×GC-MS),通过优化程序升温和调制周期,建立了喷气燃料裂解产物中芳烃的定性定量分析方法。该方法对多环芳烃(PAH)同分异构体具有良好的分离能力。利用MS检测器谱库检索结果、芳烃标准品及相关的文献报道,对喷气燃料裂解产物中常见的单环芳烃、二环芳烃、三环芳烃及四环芳烃等共27种芳烃进行了准确定性,并利用外标GC×GC-FID法对其进行定量。定量结果表明,芳烃含量均随着裂解产气率的增加而增大,当裂解产气率达到22%时,二环芳烃开始产生,且其含量随着裂解产气率的增加呈指数形式增加。该方法与传统的气相色谱-质谱相比,具有更好的分离及定性能力,可应用于复杂样品的分离及其定性定量分析。     

全二维气相色谱-飞行时间质谱分析焦化柴油中饱和烃的分子组成

建立了全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)分析柴油馏分中饱和烃的分子组成的方法。结合谱库检索、质谱图解析、沸点与分子结构关系和全二维谱图特征,定性(或归类)了焦化柴油饱和烃组分中1057个化合物单体,其中正构烷烃排列规律性最强,一环~三环环烷烃按照极性和沸点的差异呈瓦片状分布在其上方。另外,还准确区分了在一维气相色谱上共流出的正构烷基环己烷和正构烷基环戊烷,以及正构 α 单烯烃。根据质谱采集的总离子流色谱图,采用峰面积归一化法得到了饱和烃组分的碳数分布结果,并将该方法应用于研究不同类型柴油馏分饱和烃的分子组成特点。结果表明,催化裂化和焦化柴油馏分饱和烃组分的化合物类型和分布各不相同。分子组成分析能为油品加工工艺机理的研究提供方法支持。     

全二维气相色谱-氢火焰离子化检测器定性定量分析柴油中的多环芳烃

提出了全二维气相色谱-氢火焰离子化检测器(GC×GC-FID)定性定量分析柴油中多环芳烃的方法。利用全二维气相色谱-飞行时间质谱法(GC×GC-TOF MS)确定柴油芳烃的4个族组成,分别为非芳烃、一环芳烃、二环芳烃和三环⁺芳烃,获得37种定性化合物;采用峰面积归一化法对多环芳烃进行定量。结果表明：柴油质控样中多环芳烃测定值的相对误差绝对值不大于5.0%;对柴油样品进行回收试验,回收率为95.7%～104%,测定值的相对标准偏差(n=6)为1.7%～4.3%。方法用于7种实际柴油样品分析,并与NB/SH/T 0806-2022进行比对,结果显示两种方法测定值的相对误差绝对值均不大于5.0%。     

烷基苯生产中循环烷烃的液固吸附色谱预分离和气相色谱/质谱分析

 利用 10 0目～ 2 0 0目的硅胶 ,选择正戊烷和二氯甲烷作为洗脱剂 ,采用吸附色谱法将烷基苯生产中的循环烷烃分离为饱和烃 (烷烃 +环烷烃 )及芳烃两部分。然后将饱和烃及芳烃分别进行色谱 /质谱 (GC/MS)联用分析 ,得到了有关循环烷烃构成的定性定量结果。定性结果如实地反映出烷基苯生产中的副反应产物 ,可直接用于指导生产。从定量结果可以看出 ,经过硅胶吸附分离后 ,试样中含量要求很低的芳烃被浓缩 ,提高了分析的准确度和灵敏度 ,可以检测出循环烷烃中含量很低的物质 ,为全面分析样品组成提供了有力的证据。     

几种烟煤CS2萃取物的GC/MS分析

利用气相色谱－质谱联用（GC／MS）技术测定了平朔、大同和神府三种烟煤中CS2萃取物的成分，对其化学组成及结构特征进行了对比研究。结果表明，萃取物主要由脂肪烃、芳烃和含杂原子化合物三类成分组成。芳烃在萃取物整体中占绝对优势，以苯系、萘系、菲系和芘系的烷基取代芳烃为主要成分：脂肪烃除主要成份正构烷烃外，还有少量的类异戊二烯烃和萜烷；含杂原子化合物所占的比例很小，以含氧、氮和硫的化合物为主，在平朔和大同煤的CS2萃取还发现少量邻二氯苯。     

全二维气相色谱-飞行时间质谱对催化裂化汽油的定性与定量分析

采用全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)对催化裂化汽油全馏分进行了定性与定量分析,建立了相应的分析方法.结果表明,汽油族组成中的烷烃、烯烃、环烷烃、芳烃在全二维点阵谱图中呈分区域、带状的分布特点.GC×GC-TOF MS根据催化裂化汽油组分内分子的沸点及极性差异对其进行两个维度分离,极大地避免了普通色谱法分析过程中沸点相似化合物共流的弊端,实现催化裂化汽油组分的精确分离和准确定性分析.通过引入响应因子,修正了不同性质的烃类在电离源上电离效率的差异,使得TOF对催化裂化汽油族组成的定量结果与普通气相色谱法的定量结果的相关性较好,且应用GC×GC-TOF MS方法获得了催化裂化汽油更为精确的族组成信息.GC×GC-TOF MS为催化裂化汽油精确表征提供了一种有效方法.     

快速气相色谱法分析石油饱和烃

提出了一种快速分析原油和岩石抽提物中饱和烃组分的毛细管气相色谱(GC)方法。由于在该方法中采用了细内径毛细管柱,故饱和烃的GC分析周期由原来的80~90 min缩短至15 min,分析速度加快约5倍,大大提高了工作效率和仪器通量,使石油饱和烃得到了很好的分离分析。该方法符合中华人民共和国石油天然气行业标准SY/T5120-1997的要求。20万理论塔板数的细径柱的应用,可供石油中异构烷烃,尤其是甾烷、萜烷类的气相色谱/质谱(GC/MS)快速分析方法及芳烃的GC快速分析方法借鉴。     

全二维气相色谱用于轻质石油馏分中芳烃含量的测定

建立了采用全二维气相色谱(GC×GC)技术一次进样完成轻质石油馏分中非芳烃、一环芳烃和二环芳烃的分离、定性 和定量。通过对柱系统的选择和色谱条件的优化,实现了一次全二维气相色谱分析即完成轻质石油馏分的族组成分离以及 目标化合物的分离。方法的加标回收率为89.5%～106.1%;样品中各组分含量重复测定的相对标准偏差均不大于5.8%,能 够满足样品测定的精密度和准确性要求,且完成1次分析最多只需要30 min。     

白音华褐煤可溶有机质的组成和结构特征

依次采用石油醚、环己烷、二硫化碳、丙酮、甲醇和等体积的丙酮/二硫化碳混合溶剂对白音华褐煤(BL)进行分级萃取得到萃取物(E_1-E_6),利用甲醇、甲苯和等体积的甲醇/甲苯混合溶剂对萃取残渣进行连续热溶得到热溶物(SP_1-SP_3)。利用傅里叶变换红外光谱(FT-IR)、气相色谱质谱(GC/MS)和实时直接分析-质谱(DART-MS)对萃取物和热溶物的组成和结构特征进行了分析。BL总的萃取物产率和热溶物产率分别为9.37%和21.84%。E_5和E_6的FT-IR谱图中有较强的羟基吸收峰,而E_1的FT-IR谱图中脂肪C-H的伸缩振动峰强度明显高于其他萃取物;三种溶剂热溶物的FT-IR谱图相似,但SP_1和SP_3的FT-IR谱图中羟基吸收峰较强。E_1和E_5中GC/MS可检测化合物分别以烷烃和芳烃为主,E_5中还含有较多的含氧化合物;三种热溶物中化合物均以烷烃和芳烃为主,SP_3中酚类、酮类和酯类等含氧化合物的含量较高。DART-MS可检测出萃取物和热溶物中GC/MS无法检测出的较强极性和难挥发化合物;热溶物中含量较高的化合物的碳数和等价双键数(Double bond equivalent,DBE)分别集中分布在10-25和2-16,并且DBE随碳数增加而增加。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.