Water effect on peroxy radical measurement by chemical amplification: Experimental determination and chemical mechanism

The water effect on peroxy radical measurement by chemical amplification was determined experimentally for HO2 and HO2 OH, respectively at room temperature (298±2) K and atmospheric pressure (1×105 Pa). No significant difference in water effect was observed with the type of radicals. A theoretical study of the reaction of HO2·H2O adduct with NO was performed using density functional theory at CCSD(T)/6-311 G(2d, 2p)//B3LYP/6-311 G(2d, 2p) level of theory. It was found that the primary reaction channel for the reaction is HO2·H2O NO→HNO3 H2O (R4a). On the basis of the theoretical study, the rate constant for (R4a) was calculated using Polyrate Version 8.02 program. The fitted Arrenhnius equation for (R4a) is k = 5.49×107 T 1.03exp(?14798/T) between 200 and 2000 K. A chemical model incorporated with (R4a) was used to simulate the water effect. The water effect curve obtained by the model is in accordance with that of the experiment, suggesting that the water effect is probably caused mainly by (R4a).     

Reactions of fullerene C60 with methyl methacrylate radicals: A density functional theory study

We have investigated the stepwise addition of four growing methyl methacrylate (MMA) radicals to C₆₀ fullerene, taking into account all possible types of the formed adducts. This reaction set is a reliable approximation for understanding the MMA polymerization process in the presence of C₆₀ fullerene. We have analyzed the structures of the fullerene-MMA adducts and energy parameters of their formation (heat effects and activation enthalpies). We found that up to three MMA growing radicals are favorably attached to C₆₀ as the fullerene-MMA trisadduct is a stable radical of the allyl type. It is inactive for further radical addition, and the elimination of the hydrogen atom from the growing MMA radical becomes preferable. The effects of steric factors and structures of the products of multiple growing MMA radical additions to C₆₀ on the radical polymerization of MMA in the presence of C₆₀ fullerene are considered.     

可控自由基聚合系列实验教学中的一些尝试与经验*

设计了基于可控自由基聚合的系列实验教学,包括:单体和引发剂精制、RAFT试剂合成、不同单体的RAFT/ATRP聚合、RAFT聚合制备嵌段聚合物、ATRP制备嵌段聚合物等。这些实验环环相扣,互相支撑,又有着明显的对比效果。这种尝试有效改进和扩充了常规高分子合成教学中的自由基聚合部分,有效激发了学生的主动性,提高了其分析问题、解决问题的能力。     

Predictable site-selective radical fluorination of tertiary ethers

In this communication,we disclose the first example of metal-free and site-selective radical fluorination of readily available tertiary alkyl ethers,enabled by synergistic photocatalysis and organocatalysis.This catalytic combination allows for exclusive fluorination of tertiary C–O bonds under mild conditions even in the presence of competing reaction sites.The excellent functional group tolerance affords valuable access to sterically hindered alkyl fluorides through late-stage modification of complex molecules.The successful use of tertiary alkyl ethers in radical fluorination enhances the structural diversity of aliphatic fluorides that can be derived from naturally abundant alcohols.     

一例可分离的双核铁氢自由基阳离子

成功分离得到了一例双核铁氢自由基阳离子盐cis-[Fe₂Cp₂（μ-H）（μ-PPh₂）（CO）₂]^·+[Al（OC（CF₃）₃）₄]^-（cis-1^·+[Al（OC（CF₃）₃）₄]^-）晶体，并使用单晶X射线衍射、电子顺磁共振、红外光谱、紫外-可见光谱以及密度泛函理论对它进行了表征和理论计算。电子顺磁共振和密度泛函理论计算分析表明，自由基的自旋密度主要均等分布于2个铁原子上。     

利用自由基引发的1,2-炔基迁移实现非活性烯烃的炔膦酰化

研究了1,4-烯炔衍生物与二芳基膦氧化物在银介导下发生的炔酰化反应.该反应利用自由基引发的1,2-炔基迁移策略合成了一系列γ-酮膦氧化物,产率适中.该反应机理可能涉及膦中心自由基与乙烯基的加成、3-exo-dig环化和1,2-炔基迁移等连续的过程,一步形成了C-P、C-C键等化学键,实现了非活性烯烃的双官能化.     

TEMPO-mediated radical polymerization in the synthesis of poly(methyl methacrylate) macromonomer

1. Download : Download high-res image (53KB)
2. Download : Download full-size image

     

光诱导的二芳基烯丙醇氰甲基化合成δ-酮腈的反应研究

以二芳基烯丙醇与溴乙腈为原料,开发了一种可见光诱导的合成δ-酮腈的方法.控制实验的结果表明,该反应可能是通过自由基机理进行的,溴乙腈作为氰甲基自由基源参与到反应中.     

无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键研究进展

C—N键广泛存在于药物分子、天然产物及功能材料中,开发简洁高效的C—N键构建方法具有重要意义.近年来,无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键取得了诸多进展.该方法反应条件相对温和,反应活性较高,为C—N键构建提供了一条新途径.根据氮源类型的不同,对近年来C(sp^2)—H键的自由基反应构建C—N键的研究进展进行简要论述.     

可见光诱导烷基羧酸及其衍生物的脱羧偶联反应研究进展

烷基羧酸广泛存在于自然界之中,科研工作者一直致力于开发以来源丰富的烷基羧酸及其衍生物作为起始原料的反应.烷基羧酸及其衍生物在可见光氧化还原作用下可以高效地生成烷基自由基,从而在温和条件下用于构筑各类化学键.以可见光催化烷基羧酸及其衍生物的脱羧自由基反应类型为线索,系统地综述了近年来在可见光条件下烷基羧酸及其衍生物的脱羧官能团化反应研究进展.