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1.
本实验选取大同、铁法大兴、义马和神府4种煤样,用乙腈、四氢呋喃、吡啶作溶剂连续抽提后,对其中的四氢呋喃抽提物进行了凝胶色谱及二极管阵列检测分析,以确定煤抽提物中中等极性化合物的分子量分布和结构特征。通过对样品的凝胶色谱及紫外光谱分析发现,煤四氢呋喃抽提物的分子量小于840 amu,分子量分布在840~340 amu(组分1)、340~175 amu(组分2)及175~110 amu(组分3)间的组分均为芳香族化合物。但由于芳环上有不同分子量的取代基存在,使分子量分布相差极大;分子量在110 amu以下(位于标定曲线以外)的(组分4)为小分子量的链烃或脂环烃类化合物;1、2、4组分是煤四氢呋喃抽提物主要组分;而组分3在抽提物样品中含量极少。分子量在110 amu以下的小分子化合物(组分4)除大同样品中含量(8.68%)较少外,在其余3个样品中占的比例很大(神府72.96%,义马54.05%,铁法大兴51.74%)。组分1随煤变质程度增加,相对含量增加,其它组分相对含量与煤变质程度没有直接关系。  相似文献   

2.
聚氯乙烯-丙烯酸丁酯接枝共聚物的结构表征   总被引:4,自引:0,他引:4  
以通用聚氯乙烯(PVC)和脱氯化氢和PVC树脂为基体,采用悬浮溶胀接枝共聚法合成聚氯乙烯-丙烯酯丁酯接枝共聚物,对脱氯化氢和PVC和接枝共聚物的结构进行了表征。结果表明,以碱液为介质加热PVC脱除少量氯化氢,得到以链节数为2,3,4的共轭双链为主的不饱和结构,而树脂的分子量变化不大;在相同接枝反应条件下,采用脱氯化氢PVC与丙烯酸丁酯接枝共聚可以提高接枝率和接枝效率;PVC接枝共聚物的特性粘度随接枝率增加而增加,其重均分子量和分子量分布指数均在接 枝所用的PVC树脂。  相似文献   

3.
程文旦  黄锦顺 《结构化学》1993,12(6):445-448
比较了含有配位不饱和过渡金属原子簇合物Mo_2S_4(dtp)_2,(Ⅰ)和Mo_3S_4(dtp)_4·Py,(Ⅱ)的紫外—可见电子吸收光谱实验数据和半经验的量子化学方法INDO计算得到的电子跃迁能,讨论了(d-p)π型共轭作用对其电子吸收光谱位移的影响。结果表明,过渡金属簇合物中电子吸收光谱位移,与有机共轭体系有着类似的变化规律,即随着共轭π键数目增加,π-π电子跃迁的吸收光谱红移。  相似文献   

4.
通过对兖州煤与大庆减压渣油共处理重质产物的组成,分子量及分子量分布的考察,研究了甲苯可溶重质产物组成性质随反应条件的变化规律。结果表明,在较低反应温度(375-425℃)下,共处理减缓了重质产物中饱和份的转化,同时使树脂和沥青质含量降低;在较高反应温(450℃)下,由于煤与渣油的裂解程度增加,共处理与单独处理重质产物中饱和份含量均降为0,共处理重质产物的树脂+沥青质含量显著增加,共处理使重质产物的分子量增大,且随着反应温度的升高,重质产物的分子量逐渐减小,同时分子量分布逐渐变窄 。  相似文献   

5.
分子结构对1,2-聚丁二烯橡胶性能的影响   总被引:1,自引:0,他引:1  
本文研究了分子链结构、分子量及其分布对钼催化聚合1,2-聚丁二烯(1,2-PB)的加工工艺性能及硫化胶性能的影响.实验发现,1,2-PB的加工工艺行为随分子量降低和分子量分布加宽而得以改善,其抗湿滑性能随分子链中1,2-结构含量增加而提高,而1,2-结构的空间规整性—间同含量的增加则导致1,2-PB应变诱导结晶、降低硫化胶的弹性和增加生热值。  相似文献   

6.
苯乙烯与富马酸二甲酯的原子转移自由基无规共聚   总被引:1,自引:1,他引:0  
2-溴丙酸乙酯(EBP)为引发剂,CuBr为催化剂,N,N,N′,N″,N″-五甲基二亚乙基三胺(PMDETA)为配位剂的富马酸二甲酯(DMF)与苯乙烯(St)的原子转移自由基无规共聚合,转化率低于60%时,1n([M]0/[M])随聚合时间线性增加,数均分子量(Mn)随转化率性增长,所得聚合物分子量分布(PDI)较窄。根据元素分析所得共聚物的平均组成,由Kelerr—Tudos方程,计算两种共聚单体的竞聚率分别是rst=0.488,rDMF=0.303。并探讨了单体与引发剂配比以及温度对聚合反应的影响。  相似文献   

7.
选用了变质程度不同的八种煤和三种不同分子量的聚对苯乙烯磺酸钠(PSS)添加剂,详细考查了该添加剂的分子量对水煤浆浆体性质的影响。结果发现,在考查PSS相对分子量的范围内(质均分子量为5.34×104~33.39×104),八种煤的水煤浆成浆性随着分子量的增大而增加,水煤浆成浆性与PSS添加剂的平均分子量的关系可归因于添加剂在煤粒上的吸附,分子量小的PSS在煤粒上的吸附量大于分子量大的PSS;PSS分子量的增加有利于水煤浆的流变性由胀性向假塑性转变;PSS分子量的增加使水煤浆的静态稳定性得到显著的改善。  相似文献   

8.
丁伟  孙颖  吕崇福  景慧  于涛  曲广淼 《应用化学》2011,28(10):1148-1154
以季戊四醇为原料,合成了2,2-二溴甲基-1,3-二溴丙烷(PEBr4),并以此为四官能度引发剂,Cu0粉/三-(2-二甲氨基乙基)胺(Me6-TREN)为催化体系,在离子液体中实现了丙烯酰胺(AM)的单电子转移活性自由基聚合(SET-LRP),得到了窄分子量分布的星形聚丙烯酰胺(PAM),Mw/Mn约为1.26(MGPCn=14.1×103,转化率为43.4%)。 采用1H NMR对PAM结构进行表征确认,并采用GPC测定了PAM的分子量及分子量分布;考察了水、单体/催化剂(引发剂)配比对聚合反应的影响。 结果表明,少量水的加入能够加快聚合反应,使链增长速率常数由kappp=0.042 4 h-1增加至kappp=0.148 6 h-1;催化剂、引发剂用量越大,AM的SET-LRP的聚合反应速率越快,聚合反应的可控性越好,Mn随催化剂用量的增大及引发剂用量的减小而增大,且与理论分子量相近,分子量分布均呈下降趋势。  相似文献   

9.
对45℃时的氯乙烯/邻苯二甲酸二烯丙基酯(VC/DAP)的悬浮共聚进行了研究,得到表观竞聚率rVC=0769、rDAP=0374.凝胶点对应的DAP临界起始浓度在0466~0493mmol/molVC之间(聚合转化率为80~85%),当DAP起始浓度小于临界浓度时,VC/DAP共聚物均为溶胶,溶胶平均聚合度随DAP起始浓度和聚合转化率的提高而增大;当DAP起始浓度大于临界浓度时,共聚物由溶胶和凝胶组成,凝胶含量随DAP浓度和聚合转化率的提高而增加,溶胶聚合度则随DAP浓度的提高而减小.在凝胶点前,共聚物的分子量分布随DAP浓度的增加而变宽;凝胶点以后,分子量分布随DAP浓度的增加而变窄.  相似文献   

10.
煤沥青筑路油受氢改质   总被引:4,自引:0,他引:4  
研究了煤沥青在供氢剂(再生橡胶)的上,族组成随反应时间的变化规律及其受氢改质机理。利用核磁共振、元素分析、分子量测定等手段,计算得到了煤沥青、溶剂油以及改质筑路油等的平均结构参数。结果表明,与空白样对比,加入再生橡胶使得筑路油中沥青质含量由45.0%增加到61.5%,软沥青由27.0%降低到14.4%,不溶物由28.0%降低至24.1%,对比橡胶和筑路油族组成的^1H~NMR谱图可发现,在化学位移  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
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%).  相似文献   

19.
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.  相似文献   

20.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
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.  相似文献   

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