氢化铝锂—气相色谱法测定聚有机硅氧烷中硅羟基含量

硅羟基(≡SiOH)是一个较活泼的基团。聚有机硅氧烷中的硅羟基在一定条件下可以进一步相互缩合,固化成型,制成各种有用材料。该基团含量的多少对硅树脂、室温熟化硅橡胶的结构、性能、固化速度以及贮存期等都有直接影响。因此,硅羟基的测定对有机硅高分子材料的生产和研究都是很必要的。关于硅羟基的分析方法,前人做了不     

红外光谱法测定端羟基聚丁二烯(HTPB)胶粘体系的固化度

介绍用红外光谱法测定端羟基聚丁二烯（HTPB）胶粘体系固化度的原理及方法，并对端羟基聚丁二烯胶粘体系固化过程进行监控，分析了一定温度下胶粘体系的固化度与固化时间，以及相同固化时间内胶粘体系的固化度与固化温度之间的数学关系。     

流化床反应器中α-FeOOH粒子表面水解包覆SiO2过程研究

研究了流化床反应器中α－ＦｅＯＯＨ粒子表面脱水与正硅酸乙酯（ＴＥＯＳ）水解反应形成ＳｉＯ２包覆层的过程,结果表明,α－ＦｅＯＯＨ脱水促进了粒子表面水解反应,有利于形成均匀的ＳｉＯ２包膜,同时还进一步研究了反应温度、反应时间、ＴＥＯＳ浓度和氨浓度对ＳｉＯ２包覆量的影响,采用这一技术,一步实现了脱水、包覆和还原过程,得到了性能良好的ＳｉＯ２包覆了Ｆｅ２Ｏ４磁性粉末。     

有机硅改性UV固化水性环氧树脂的研究

以环氧树脂E-51、甲基三乙氧基硅烷为原料,用接枝共聚的方法合成了有机硅改性水溶性UV固化环氧树脂,该方法有效地改善了环氧树脂的柔韧性、水溶解性,提高了成膜物的机械性能,其拉伸强度达到53.5 MPa,断裂伸长率为46.5%,耐冲击性大于50 kg/cm。通过红外光谱、热重分析表征产物的结构和性能,结果表明,有机硅已经成功接枝到环氧树脂的分子上。有机硅改性后环氧树脂在400℃的分解率由之前的60%降至40%。文章同时讨论了有机硅改性水性UV固化环氧树脂合成中反应温度、有机硅种类以及加入量等对UV固化水性环氧树脂成膜物的附着力、耐水性及耐碱性的影响,以此获得最佳反应条件:质量分数为14.4%的甲基三乙氧基硅烷与羧酸改性的环氧树脂在90℃下反应5～6 h。     

含磷有机硅杂化环氧树脂固化体系性能研究

通过磷酸与γ-环氧丙氧基三甲氧基硅烷反应得到含磷有机硅氧烷,并加入到环氧树脂/4,4'-二氨基二苯基甲烷体系中混合,通过溶胶-凝胶的方法制备了含磷有机硅杂化环氧树脂固化物.对固化体系进行了玻璃化转变温度、热失重、阻燃、拉伸强度、冲击强度测试分析.结果表明,该固化体系的阻燃性得到提高,极限氧指数在25.8～29.3,玻璃化转变温度得到提高,在161～179℃;虽然初始分解温度比纯环氧树脂固化物低,但800℃残炭率可以达到26.5%,提高了36%;拉伸强度得到提高,在71～94 MPa,冲击强度可以达到14.36 kJ/m2,提高了14%.该固化体系具有较好的阻燃性能和热性能,同时具有较好的力学性能.     

EO／THF无规共聚醚结构研究（II）—NMR方法研究溶剂配合物与溶…

用１Ｄ－ＮＭＲ和２Ｄ－ＮＭＲ方法研究了ＥＯ／ＴＨＦ共聚醚（ＴＥＯ）的溶液行为，ＴＥＯ浓溶液状态，其溶液浓度不仅使谱峰化学位移值增减，而且使峰型发生较大的变化，当改变温度时，ＣＮＭＲ谱在高场区有如同溶剂化效应的过程，实验结果表明，浓度与温度使ＴＥＯ溶液分子内部结构发生变化，２Ｄ－ＮＯＥＳＹ实验表明：在低浓度情况下，ＴＥＯ分子易与活泼氢溶剂生成配合物，分子间偶极－偶极相互作用受温度和浓度的影响。     

乙醇分子间脱水制乙醚

醇能发生脱水反应,这是由于醇分子内有羟基决定的。乙醇的脱水其一是分子内脱水,其二是分子间脱水;分子内的脱水发生消除反应生成乙烯,分子间的脱水发生取代反应,即一个醇分子的羟基被另一个醇分子的烷氧基所取代生成乙醚。     

酚醛／石墨导热塑料的固化动力学研究

采用动态ＤＳＣ技术研究热固性酚醛／石墨导热塑料反应固化工艺过程，建立动力学方程，利用动力学方程和动力学参数进一步得到固化反应程度、固化反应温度以及固化反应时间三者之间的关系。动力学参数为ｌｎ＝６．７８，Ｅ＝４６．８６ＫＪ／ｍｏｌ，ｎ＝０．９７；该材质理论上较为合适的固化温度Ｔ＝２００℃，固化时间ｔ＝１５ｍｉｎ。     

EO／THF无规共聚醚结构研究（Ⅱ）──NMR方法研究溶剂配合物与溶液行为

用１Ｄ－ＮＭＲ和２Ｄ－ＮＭＲ方法研究了ＥＯ／ＴＨＦ共聚醚（ＴＥＯ）的溶液行为。ＴＥＯ在浓溶液状态，其溶液浓度不仅使谱峰化学位移值增减，而且使峰型发生较大的变化。当改变温度时，~（１３）ＣＮＭＲ谱在高场区有如同溶剂化效应的过程，实验结果表明：浓度与温度使ＴＥＯ溶液分子内部结构发生变化。２Ｄ－ＮＯＥＳＹ实验表明：在低浓度情况下，ＴＥＯ分子易与活泼氢溶剂生成配合物，分子间偶极－偶极相互作用受温度和浓度的影响。     

毛细管区带电泳对羟基苯甲酸三种异构体的分离研究

考察了邻羟基苯甲酸、间羟基苯甲酸和对羟基苯甲酸在毛细管区带电泳分离时的行为。研究了缓冲液pH、浓度和分离电压对三种羟基苯甲酸异构体分离的影响,结果表明在10 mmol/L Na2HPO4缓冲体系(pH 10.15),运行电压25kV,实验温度25℃的分离条件下,采取压力进样(3.4 kPa×3 s),检测波长210nm;3种异构体在7 min内获得基线分离。邻羟基苯甲酸、间羟基苯甲酸、对羟基苯甲酸在2~100μg/mL范围内,峰面积与质量浓度具有较好的线性关系,检出限分别是0.96,1.27和1.07μg/mL。     

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%).     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

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.