煤中含氧官能团的红外光谱定量分析

利用ＦＴＩＲ分析和合适的光谱分峰程序,把煤的红外吸收光谱分解为３８个Ｇａｕｓｓｉａｎ分布的峰。基于煤中含氧官能团在红外光谱中有吸收,并结合煤中含氧官能团的化学分析,确定了含氧官能团与其吸收强度之间的关系。对我国煤化程度有显著差异的１８种煤的红外光谱的研究表明,羧基、羟基和其它含氧官能团的氧含量均随煤化程度的增加而减少,煤中官能团的氧含量是煤化程度的量度     

13C固体核磁共振分析煤中含氧官能团的研究

采用 ¹³C交叉极化/魔角旋转-核磁共振（¹³C CP/MAS NMR）技术对四种煤进行分析,结合化学分析方法,考察了含氧官能团的分布规律,尤其是非活性醚键的含量。结果表明,¹³C CP/MAS NMR方法可以定量分析煤中部分含氧官能团,四种煤中羧基和羰基的含量分别为0.00~1.41和0.45~1.91 mol/kg;¹³C CP/MAS NMR与化学分析方法结合,可以定量解析煤中非活性醚键的含量,四种煤的醚键含量值为5.33~10.54 mol/kg,而活性醚键含量仅为0.04~0.13 mol/kg,煤中醚键的赋存状态以非活性醚键为主。     

低阶煤中含氧官能团分布的研究

采用化学法测定了四种典型中国低阶煤中羧基、醇羟基、酚羟基、甲氧基和羰基含氧官能团。其中,羧基的定量分析采用醋酸钙溶液和pH值为8.3的缓冲溶液进行,分析了测定条件对羧基和酸性含氧官能团测定结果的影响。结果表明,在N₂气氛下比空气条件下测定羧基含量准确,褐煤中羧酸根的主要存在形式为羧酸盐,酸洗后煤样中酚羟基的测定值随着离子交换溶液pH值的增加而增大;褐煤中的含氧官能团主要是羧基和羟基,分别占总氧量的34.49%和34.79%;在不同低阶煤中存在不同含量的羰基,甲氧基含量较小。     

水热法改性褐煤及含氧官能团与水相互作用的研究

利用水热法对蒙东褐煤进行了改性。通过微量热仪测定和分析了煤炭表面骨架大分子和各种官能团与水结合能的大小。结果表明,水热法改性后,褐煤中的羧基和羰基随温度升高显著降低,而羟基的变化比较复杂。计算得到了低阶煤中含氧官能团和煤炭表面骨架大分子亲水能力由大到小的顺序是羧基酚羟基羰基煤炭表面骨架大分子。     

活性炭的表面含氧官能团及其对吸附影响的研究进展

对活性炭表面含氧官能团的种类,生成原因以及活性炭含氧官能团的定性定量分析方法进行了综述。含氧官能团改变了活性炭的表面性质和表面行为,导致活性炭对金属离子和有机物的吸附性能发生变化,介绍了吸附金属离子和有机物时含氧官能团参与的作用机理,并对含氧官能团影响的研究提出了一些建议。     

褐煤模型化合物中含氧官能团脱出反应的理论研究

选取苯甲酸和苯酚作为褐煤含氧官能团模型化合物,采用密度泛函理论(DFT)中的B3LYP泛函和6-311+G(d,p)基组,研究了羧基和羟基可能的脱出反应机理.结果表明,不同含氧官能团脱出方式不同,脱出所需的能量也有差异;含有羧基物质的自催化交联脱羧是相对容易发生的反应;考虑到水分子对含氧官能团脱出的影响,选取甲酸和丙三醇作为褐煤含氧官能团模型,研究了水分子参与反应的过渡态结构及其反应活化能的变化,结果表明,反应中水分子作为质子传递介质能降低反应活化能,加快反应速率,一般1~2个水分子的催化效果较佳;同时研究了Na+,K+及其羧酸盐对丙三醇中羟基脱出反应过渡态结构和反应活化能的影响,表明Na+和K+均能与模型化合物形成络合物,稳定过渡态结构,降低活化能,其中Na+的催化效果更佳;与单纯的离子相比,K+羧酸盐催化效果变化不大,Na+羧酸盐催化能力降低幅度较大.     

活性炭表面含氧官能团对二噁英吸附的影响机制研究

以分子结构和性质与二噁英相似的二苯并呋喃为模型化合物,椰壳炭为吸附剂,在120?℃条件下进行了吸附实验.将硝酸改性后的样品分别在300、500、800?℃进行热处理,比较了原始样品和改性后的椰壳炭对二苯并呋喃的吸附能力.并利用BET、TPD-MS、元素分析等手段对改性前后椰壳炭的物理化学性质进行了表征.结果表明,硝酸改...     

3种酸氧化法制备的功能化多壁碳纳米管中含氧官能团含量的比较

通过定量测定碳纳米管表面含氧官能团对其功能化程度进行了评估.采用3种方法制备了酸氧化多壁碳纳米管(c-MWNTs),并对比了其分散稳定性,通过扫描电镜(SEM)和红外光谱法(FTIR)对其进行定性表征,分别用NaHCO3,Na2CO,及NaOH选择性地与c-MWNTs表面不同的酸性位点发生反应,利用酸碱滴定法定量测定其...     

煤及其含氧基团模拟物的电化学还原

以四丁基溴化铵作支持电解质电化学还原煤及其含氧基团模拟物,用甲醇萃取电化学还原前后的煤.还原产物和萃取物由气相色谱-质谱联用仪定性分析,煤含氧基团模拟物的电还原产物用气相色谱定量分析.结果表明,经电化学还原后,煤表面含氧基团减少,需进一步提高煤含氧基团模拟物的转化率.电化学测试同时给出还原过程中各相关电极反应的动力学方程.     

低煤化度煤低温热解脱氧后结构的变化

采用低温热解脱氧方法对低煤化度煤中含氧官能团化学活性进行了系列研究,测定了ＦＴＩＲ、１Ｈ－ＮＭＲ、１３Ｃ－ＮＭＲ及比表面积和孔径分布。得出了煤中含氧官能团的化学活性顺序,并发现低温热解脱氧的同时,煤分子中的Ｏ重新分布,Ｈ分布、Ｃ分布及孔径分布的变化,是低温热解导致煤分子改性的原因所在     

聚合物支载的常见功能基团的分析鉴定方法

综述了目前用于固相有机合成中聚合物支载的功能基团的各种分析鉴定方法。     

Trifluoromethylation of Alkenes with Concomitant Introduction of Additional Functional Groups

The trifluoromethyl group is found in many synthetic bioactive compounds, and the difunctionalization of a C?C bond, as a powerful strategy for the construction of compounds with various functional groups, has been intensively investigated. Therefore, the difunctionalizing trifluoromethylation of alkenes has attracted growing interest because of the potential of the products as building blocks for bioactive molecules. In this review, we focus on recent advances in the trifluoromethylation of alkenes with concomitant introduction of additional functional groups.     

Introduction of Fluorine and Fluorine‐Containing Functional Groups

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo‐ and transition‐metal catalysis. The most challenging transformation remains the formation of the parent C? F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal—fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost‐efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.     

酞菁钴催化剂载体表面含氮官能团对其在燃料电池中氧还原性能的影响

以酞菁钴为催化剂,纳米碳管为载体,分别通过超声法和四氢呋喃法混合分散,并在氮气氛围高温热处理制备了两种酞菁钴催化剂.热重分析（TGA）结果显示超声法制备的酞菁钴催化剂（CoPc-CNT-S）含钴的质量分数为8.1 wt%,四氢呋喃混合法制备的酞菁钴催化剂（CoPc-CNT-R）含钴的质量分数为7.0 wt%.X射线光电子谱（XPS）结果显示CoPc-CNT-R催化剂的含氮量是CoPc-CNT-S催化剂的两倍多,且两种催化剂含氮官能团的种类及比例不同.相比较而言,CoPc-CNT-S表面有更多的吡咯型氮.将两种催化剂应用于混合酸碱燃料电池中发现：CoPc-CNT-S对电催化氧还原有较高的活性和稳定性,将CoPc-CNT-S作为燃料电池的阴极催化剂分别工作5 h和15 h后,电荷转移电阻相对CoPc-CNT-R为阴极催化剂时均较低.原因可能是相近比例的吡啶型N和吡咯型N的协同作用有利于电催化氧还原.     

基于氧硫功能团载体的铅离子电位传感器的研究与进展

系统总结归纳了基于氧硫功能团载体的铅离子电位传感器,具体涉及到蒽醌、芳羧酸、羧酸酯、磷酸酯和含酰胺、硫酰胺大环化合物等.蒽醌类载体普遍具有较快的铅离子响应速度,响应时间为2s.含硫芳香羧酸对铅离子的传感普遍较为敏感,构建不对称膜后,探检出限改善至6.0× 10-10 mol/L.磷酸酯则具有很强的抗干扰能力,大部分金属离子选择系数logK均小于-3.0.而含酰胺基团的大环化合物载体已构建成微型传感器,从而可探测受限于3 μL测量池的样品,检出限达2.7×10-9 mol/L.     

Acceptor Derivatization of the 4CzIPN TADF System: Color Tuning and Introduction of Functional Groups

We demonstrate modular modifications of the widely employed emitter 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) by replacing one or both nitrile acceptors with oxadiazole groups via a tetrazole intermediate. This allows the introduction of various functional groups including halides, alkynes, alkenes, nitriles, esters, ethers and a protected amino acid while preserving the thermally activated delayed fluorescence (TADF) properties. The substituents control the emission maximum of the corresponding emitters, ranging between 472–527 nm, and show high solid-state photoluminescence quantum yields up to 85 %. The TADF emission of two compounds, 4CzCNOXDtBu and 4CzdOXDtBu, a mono- and a bis-oxadiazole substituted 4CzIPN is characterized in detail by time- and temperature-dependent photoluminescence. Solution-processed OLEDs comprising 4CzCNOXDtBu and 4CzdOXDtBu show a significant blue-shift of the emission compared to the reference 4CzIPN, with external quantum efficiencies of 16 %, 5.9 % and 17 % at 100 cd m⁻², respectively.     

Reactive Groups,Spacer Groups and Functional Groups in Macromolecular Design

Several aspects of modern design of macromolecular architecture are discussed: the influence and importance of functional groups which often dominate the characteristics of the macromolecular structure; the importance of the spacer groups that provide flexibility and allow the functional group to act independently from the main chain when the functional group is attached to the main chain.

Examples are given for the synthesis of reactive, telechelic polymers, for polymerizability of monomers whose polymerizable group is separated from the functional group by a flexible methylene spacer, and the reactivity of functional groups separated from the main chain by a spacer group.     

Pyrylium Mediated Transformations of Primary Amino Groups into Other Functional Groups. New Synthetic Methods (41)

The first pyrylium salt was isolated some 80 years ago, yet up to the 1950s only moderate interest was taken in the preparation, properties and uses of such salts. However, the past thirty years has seen a phenomenal growth in the literature pertinent to this area of chemistry: the importance of pyrylium salts as intermediates has been realized. They are readily prepared by a variety of generally applicable routes, and they are highly reactive towards nucleophiles. Together, this enables the convenient synthesis of a great variety of acyclic and heterocyclic compounds. We have used highly substituted pyrylium salts for the two-step conversion of the amino group in alkylamines RNH₂ into numerous other functionalities. In the first step, the pyrylium salts are converted with the amines into N-substituted pyridinium salts, which, in the second step, react with Nu^? to give the desired products RNu. In some cases the R moiety is also changed, e.g. by elimination. Studies of the reactions of these pyridinium salts have allowed interesting insights into the mechanisms of nucleophilic substitution, in addition to rendering aliphatic amines important synthetic intermediates. Thus, the method complements the diazotization procedure for the transformation of arylamines.     

化学新课导入方法研究

“良好的开端是成功的一半”。本文从新课导入功能、常见新课导入方法及分类、如何进行新课导入的设计3个方面对新课导入进行研究,并结合“离子键”一节导入的设计,对新课导入加以深入、具体的阐述。