甲基丙烯酸甲酯的原子转移自由基悬浮聚合

以 1 苯基氯乙烷为引发剂 ,氯化亚铜为催化剂 ,2 ,2 联吡啶为配体 ,外加搅拌 ,氮气保护下进行了甲基丙烯酸甲酯 (MMA)在 80℃下的原子转移悬浮聚合 .结果表明 ,聚合反应符合对单体浓度为一级的动力学关系 .经计算聚合体系的增长自由基浓度为 5 .74× 10 - 8mol L .聚合物分子量随转化率呈线性增加 ,分子量分布较窄 ,Mw Mn 在 1.37～ 1.40之间 .还以AIBN为引发剂 ,在三氯化铁和三苯基膦存在下进行了MMA的反向原子转移本体和悬浮聚合研究 .结果证明本体聚合具有好的可控特征 ,分子量随转化率呈线性增长 ,分子量分布指数在 1.2 7～ 1.31之间 .聚合反应速率较快 ,聚合体系中的增长自由基浓度较高 ,为 1.6 4× 10 - 7mol L .而在此催化体系下的悬浮聚合则完全失去了活性特征     

红外光谱法研究苯乙烯原子转移自由基聚合反应动力学

利用红外光谱法测定反应转化率研究原子转移自由基聚合反应动力学。在环己酮溶液中,以卤代烃为引发剂,过渡金属卤化物与配位剂２,２‘－联吡啶为催化体系,进行了苯乙烯聚合。分别就反应温度,反应物浓度和引发体系对苯乙烯聚合速率的影响进行了动力学测定,证实了原子转移自由基聚合具有活性聚合的特征,同时计算并讨论了苯乙烯原子转移自由基聚合反应的动力学数据。     

原子转移自由基聚合及可控自由基聚合

以作者在原子转移自由基聚合领域的研究成果为主导,结合国内外文献,对近年来出现的颇具影响的可控自由基聚合体系与进行了评述与展望。     

氢氧根对苯乙烯和甲基丙烯酸甲酯ATRP悬浮共聚的影响

在85℃下,以α-溴异丁酰溴为引发剂、氯化亚铜为催化剂、2,2′-联吡啶(bpy)为配体,研究了氢氧化钠(NaOH)含量对苯乙烯和甲基丙烯酸甲酯的原子转移自由基悬浮共聚合的影响。1H-NMR分析和共聚竞聚率(rSt=0.83,rMMA=0.82)表明St/MMA原子转移悬浮共聚容易形成恒比共聚。ATRP的悬浮聚合表现出较好的可控/活性特征。在试验水相中氢氧根浓度为0至3%的范围内,单体转化率、ln[M]0/[M]和表观反应速率常数kappp都随着氢氧根浓度增大而增大。氢氧根并不影响聚合反应的一级动力学特征,但具有加速St/MMA原子转移悬浮共聚反应的作用。探讨了氢氧根在St/MMA原子转移悬浮共聚反应中的作用机理。     

含有热引发转移终止剂的引发体系在反向原子转移自由基聚合中的应用

原子转移自由基聚合 (ATRP)是实现活性聚合的一种颇为有效的途径 ,可以实现多种单体的活性自由基聚合 .反向原子转移自由基聚合 (ReverseATRP)的概念始提出于 1995年 ,是对传统ATRP的改进和拓展 .近年来关于此体系的引发剂的拓展、过渡金属及单体的适用性都得到了很大发展 .本文简要综述了我们研究组在反向原子转移自由基聚合方面的研究进展     

水介质中可控/活性自由基聚合的研究进展

综述了均相水溶液体系和分散，悬浮，乳液及微乳液等非均匀相水溶液体系中的可控／活性自由基聚合的研究现状，对一些最常见的可控自由基聚合方法，如氮氧调控聚合，原子转移自由基聚合和可逆加成－继裂链转移聚合方法的聚合情况进行了详细的介绍，展望了水介质中可控／活性自由基聚合的发展方向及前景。     

多官能团乙烯基单体原子转移自由基交联聚合机理

乙烯基单体;原子转移自由基交联聚合;聚合机理;交联网络     

原子转移自由基聚合的研究进展

综述了原子转移自由基“活性”聚合研究的进展，包括采用的各种引发体系，聚合反应机理，动力学研究以及所合成的各种模型聚合物。通过原子 转移自由基聚合可以方便地合成各种结构的模型聚合物，２包括窄分的均聚物，交替，无规和渐变共聚物、特殊链端的聚合物，嵌段和接枝共聚物等。     

甲基丙烯酸甲酯原子转移自由基聚合等规度研究

在０－１００℃温度范围内,由原子转移自由基聚合方法,采用助催化和非助催化体系,引发甲基丙烯酸甲酯聚合,利用＾１３Ｃ ＮＭＲ测定聚甲基丙烯酸甲酯的等规度,发现原子转移自由基聚合仍以间同位构为主,随着聚合温度的升高间同立构等规度降低,与通常自由基聚合对有规立构控制特性相似,助催化剂异丙醇铝和活性端羟基配位,对聚合物的规整性有一定的影响。     

甲基丙烯酸缩水甘油酯的常温原子转移自由基活性聚合

甲基丙烯酸缩水甘油酯的常温原子转移自由基活性聚合     

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.     

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.     

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.