富勒醇清除OH自由基的ESR研究

富勒醇清除·ＯＨ自由基的ＥＳＲ研究祝严师，孙大勇，刘桂珍，刘子阳，詹瑞云，刘淑莹（中国科学院长春应用化学研究所应用谱学开放实验室，长春，１３００２２）关键词Ｃ_（６０），富勒醇，ＯＨ自由基，自旋捕捉，ＥＳＲ生物体内的许多现象均涉及到自由基反应，现已发?..     

H2O2-四丁基溴化铵-醋酸盐体系中肉桂酸的吸附平行催化波研究

在醋酸盐（ＰＨ＝４．０）－四丁基溴化铵（Ｂｕ_４Ｎ·Ｂｒ）－Ｈ_２Ｏ_２缓冲溶液中，用线性扫描示波极谱法、循环伏安法和数字模拟法等方法研究了肉桂酸（Ｃ_６Ｈ_５－ＣＨ＝ＣＨ—ＣＯＯＨ）的 吸附平行催化波产生机理．结果表明，肉桂酸的还原机理为 ＥＣ_ｄｉｍＥ’过程，即内桂酸的Ｃ＝Ｃ双键首先发生ｌｅ，１Ｈ~＋还原（Ｅ）产生一个中间体自由基Ｃ_６Ｈ_５－Ｃ·Ｈ－ＣＨ_２－ＣＯＯＨ，随后该自由基在以ｌｅ，１Ｈ~＋方式进一步还原（Ｅ’）的同时伴随着该自由基间的二聚化反应（Ｃ_ｄｉｍ）．由于Ｂｕ_４Ｎ~＋质点的诱导吸附作用，肉桂酸的极谱电流增加，峰电位正移．Ｈ_２Ｏ_２氧化肉桂酸还原中间体自由基使原Ｃ＝Ｃ双键再生（Ｃ’），同时阻止了该自由基的进一步还原和二聚化反应，产生了平行催化波．该催化波的产生机理为ＥＣ＇过程．Ｈ_２Ｏ_２氧化肉桂酸自由基的表观速率常数Ｋ_ｆ为 １．３５ ×１０~２ｍｏｌ· Ｌ~(－１)· ｓ(－１)．提出了一种有机化合物极谱催 化波的新类型──由表面活性剂和氧化剂双增敏的吸附平行催化波．     

双电荷离子［C_（12）H_（12）N_2O］~（2＋）和［C_（12）H_（12

双电荷离子［Ｃ_（１２）Ｈ_（１２）Ｎ_２Ｏ］~（２＋）和［Ｃ_（１２）Ｈ_（１２）Ｎ_２Ｓ］~（２＋）的气相单分子分解反应研究任达，贾维平，李智立，刘淑莹（中国科学院长春应用化学研究所，长春，１３００２２）关键词双电荷离子，质量分析离子动能谱，串联质谱，４...     

2，5－二叔丁基对二甲氧基苯的去叔丁基反应的研究

２，５－二叔丁基对二甲氧基苯（１）在ＣＦ_３ＣＯ_２Ｈ，ｎ－Ｃ_３Ｆ_７ＣＯ_２Ｈ或ＡｌＣｌ_３－ＣＨ_２Ｃｌ_２体系中易发生去叔丁基化反应，而在强质子酸ＨＩ（ａｑ）．ＨＢＦ_４或ＣＣｌ_３ＣＯ_２Ｈ中不发生此反应。在前一类体系中，都可在反应过程中观察到较强的阳离子基１￣＋的ＥＰＲ信号，而在后一类体系中则无此信号。动力学测定表明，受物１与三氟乙酸的反应表现为三级动力学，其中１为二级，ＣＦ_３ＣＯ_２Ｈ为一级。这些结果揭示了去叔丁基化反应与离子自由基的形成有着内在的联系。     

C60硫衍生物—C60S^＋的气相合成

Ｃ_（６０）硫衍生物──Ｃ_（６０）Ｓ~＋的气相合成刘子阳，郝国仑，郭兴华，刘淑莹（中国科学院长春应用化学研究所，长春，１３００２２）关键词Ｃ_（６０），ＣＳ_２，离子－分子反应自实现Ｃ（６０）的宏观量合成以来［１］，通过将Ｃ（６０）进行化学衍生进而改变?..     

钌（Ⅱ）—邻菲咯啉偶合化学发光法测定Fenton反应产生的羟自由基

提出了一种测定Ｆｅｎｔｏｎ反应产生羟自由基的偶合化学发光分析法。羟自由基与苯甲酸发生烃化反应后生成的羟基苯甲酸能增大钌（Ⅱ）邻菲咯啉－Ｃｅ（Ⅳ）化学发光反应的发光强度。用化学发光法测定羟基苯甲酸的含量可间接测定自由基的生成量。拟定的方法,简单,灵敏度高,可用于筛选羟自由基消除剂。     

CH（B~2Σ~－）和卤代甲烷、CS_2、O_2及Ar碰撞过程动力学研究

用四倍频ＹＡＧ激光（２６６ｎｍ）光解ＣＨＢｒ_３产生ＣＨ（Ｂ~２Σ~－）自由基，通过测量自发辐射ＣＨ（Ｂ→Ｘ）的时间分辨信号测得室温下ＣＨ（Ｂ）被卤代甲烷、ＣＳ_２、Ｏ_２及Ａｒ的猝灭速率常数（×１０~（－１０）ｃｍ~３·ｍｏｌｅｃ~（－１）·ｓ~（－１））分别为４．４±０．７（ＣＨ_２Ｃｌ_２）、５．２±０．４（ＣＨＣｌ_３）、５．０±０．７（ＣＣｌ_４）、８．２±０．３（ＣＨＢｒ_３）、７．９±０．７（ＣＳ_２）、０．１９±０．０２（Ｏ_２）及（１．１±０．１）×１０~（－２）（Ａｒ）．结果表明，除Ｏ_２外，其它猝灭剂对ＣＨ（Ｂ）的猝灭速率常数均大于对ＣＨ（Ａ）的。对卤代甲烷分子，猝灭速率常数显示了因Ｃｌ原子数增加而增加的趋势。     

典型无机含氧酸自由基的特性

碳酸自由基、硝酸自由基、磷酸自由基和硫酸自由基是化学反应的重要中间体，都具有氧化性，对污染物在自然和人为环境中的迁移转化会产生重要的影响.文中较为详细地介绍这几种自由基的电极电位、产生方式、检测方法及与有机物的反应方式.总结四种自由基的特性及与有机物的反应方式可发现，四种自由基和羟自由基电极电位不同，导致它们和有机物反应速率的不同；碳酸自由基并不是羟自由基去除剂，对于一些容易被氧化的化合物，碳酸自由基氧化效果比羟自由基好；四种自由基均可由羟自由基转化而来，并且这四种自由基和羟自由基与有机物反应方式基本一致，都通过电子转移、夺氢和加成的方式进行.可以预测四种自由基和羟自由基降解有机物的机理将非常相似，今后应研究四种自由基与羟自由基相互转化的规律，以及与代表性有机物的反应机理.     

乙烯基炔与一氧化氮反应机理的理论探讨

利用半经验AM1方法，研究了乙烯基乙炔与一氧化氮反应生成丙炔腈（反应1）和丙烯腈（反应2）的两条竞争反应途径．采用Berny梯度法优化得到了反应势能面上的所有驻点，并逐一进行了振动分析确认．结果表明，反应互较反应Ⅱ易引发（即；NO比较容易与乙烯基乙炔进行分步的1，4-加成，形成六元环过渡态及中间体，最终消除CH2O和H自由基后生成丙炔腈），而反应Ⅱ较难引发（NO与乙烯基乙炔较难进行1，2-加成，形成四元环过渡态及中间体），但一经引发，就能较容易地进行分步裂解，生成丙烯腈和CHO自由基．     

MZrO3（M=Ba,Sr,Ca）水热合成中结构与反应活性的关系

ＭＺｒＯ_３（Ｍ＝Ｂａ，Ｓｒ，Ｃａ）水热合成中结构与反应活性的关系郑文君，庞文琴（吉林大学化学系，长春，１３００２３）关键词水热合成，ＭＺｒＯ_３（Ｍ＝Ｂａ，Ｓｒ，Ｃａ），结构，反应活性钙钛矿型复合氧化物ＭＺｒＯ３（Ｍ＝Ｂａ，Ｓｒ，Ｃａ）是重要的功能陶...     

Kinetics and Mechanism of the Reaction of Chloroplatinum(II) Complexes with Alkyl Radicals

The reaction between certain platinum(II) complexes and alky radicals produces an unstable organoplatinum(III) intermediate, {Pt^III -R}. The kinetics of this step were evaluated by laser flash photolysis with ABTS² (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) ion) and TMPD (tetramethylphenylenediamine) as kinetic probes. The rate constants for PtCl₄^2? are: k_Pt/10⁸ L mol^?1 s^?1 = 5.2, 2.8 and 0.27 for CH_3, C₂H₅, and CH₂Cl in aqueous solution at pH 1. Those with cis-Pt(NH₃)₂Cl₂ are somewhat smaller, and those for Pt(NH₃)₄²⁺ too small to measure will) this technique. The product analysis indicates that the decomposition of organoplatinum takes place by hydrolysis and (for R = C₂H₅ only) by β-elimination, The kinetic isotope effect on die β-elimination of DCH₂CH₂PtC₄,^2? is k_H/k_D = 1.2. The β-elimination step produces a Pt^III-hydride that releases hydrogen gas and forms {Pt_III-OH}. The short-lived Pt(III) intermediate may disproportionate or oxidize the Co^II complex that is produced in the radical-generating step.     

Transition-metal-free regioselective thiocyanation of phenols,anilines and heterocycles

An expedient direct and regioselective thiocyanation of phenols, anilines and heterocycles is described. Transformation is realized via the direct CH functionalization under transition metal free conditions at ambient temperature in excellent yields. Method proved to be monoselective and variety of functional groups tolerated the reaction conditions. The practicality of the protocol is demonstrated in gram scale synthesis of a precursor of PPAR δ agonist in excellent yield.     

Electron Transfer through DNA in the Course of Radical-Induced Strand Cleavage

No benefit from base stacking is observed for rates of electron transfer in DNA. This conclusion was drawn from experiments with a new DNA assay in which a radical cationic site, generated by strand cleavage, can be reduced by the guanine bases in the same DNA (the electron transfer is indicated by arrows in the diagram). The distance dependence of this electron transfer step is determined by the chemical yield of the reduction product.     

Synthesis and polymerization of novel fluorinated acrylates and methacrylates bearing alkoxyl groups derived from radical addition reaction of perfluoroisopropenyl ester

Radical addition of 2-benzoxypentafluoropropene [CF₂C(CF₃)OCOC₆H₅] (BPFP) with alcohols such as ethanol and 2-propanol was investigated to afford fluorinated alcohols. Radical addition of BPFP with cyclic ethers such as tetrahydrofuran, 1,3-dioxolane and tetrahydropyran was also achieved to afford addition products followed by hydrolysis to yield fluorinated alcohols possessing cyclic structures. Novel fluoroalkyl acrylates and methacrylates were synthesized from the fluorinated alcohols with (meth)acryloyl chlorides. Radical polymerization of the fluoroalkyl (meth)acrylates yielded polymers of 1.2 × 10⁵ as the highest molecular weight.     

Formyl Radical Generation from α-Chloro N-Methoxyphthalimides Enables Selective Aldehyde Synthesis

The aldehydes installation by radical formylation constitutes an attractive synthetic strategy. However, the generation of formyl radicals for organic synthesis applications remains unknown. Herein we report the first formyl radical generation from α-chloro N-methoxyphthalimides, which selectively synthesize aldehydes by alkene hydroformylation under mild photoredox conditions. The aldehydes can be installed on acrylates, acrylamides, vinyl sulfones, vinyl ketones, and complex steroids by radical hydroformylation in excellent chemoselectivity and regioselectivity. The concerted hydrochloride elimination for the formyl radical generation from α-chloro methoxy radicals is established by experimental and computational approaches.     

A Strategy for Controlling the Polymerizations of Thiyl Radical Propagation by RAFT Agents

The ability to extend the polymerizations of thiyl radical propagation to be regulated by existing controlled methods would be highly desirable, yet remained very challenging to achieve because the thiyl radicals still cannot be reversibly controlled by these methods. In this article, we reported a novel strategy that could enable the radical ring-opening polymerization of macrocyclic allylic sulfides, wherein propagating specie is thiyl radical, to be controlled by reversible addition–fragmentation chain transfer (RAFT) agents. The key to the success of this strategy is the propagating thiyl radical can undergo desulfurization with isocyanide and generate a stabilized alkyl radical for reversible control. Systematic optimization of the reaction conditions allowed good control over the polymerization, leading to the formation of polymers with well-defined architectures, exemplified by the radical block copolymerization of macrocyclic allylic sulfides and vinyl monomers and the incorporation of sequence-defined segments into the polymer backbone. This work represents a significant step toward directly enabling the polymerizations of heteroatom-centered radical propagation to be regulated by existing reversible-deactivation radical polymerization techniques.     

自由基聚合中扩散效应分析

自由基聚合扩散效应包括“笼蔽效应”、凝胶效应和玻璃化效应,本文以聚合物大分子扩散理论发展为线索,首先讨论了基于粘度理论、标度理论、链缠结理论、自由体积理论等从宏观尺度描述自由基聚合扩散效应的模型,然后深入到微观分子尺度,从初级自由基的扩散行为讨论了“笼蔽效应”,基于增长自由基的三种扩散行为解释了凝胶效应和玻璃化效应,最后简单介绍了其他理论模型,并对理论未来的发展进行了展望。     

Synthesis and atropisomerism of 2,2′-ortho disubstituted biphenyls

The role of substitution on the aromatic rings for the synthesis of 2:2 disubstituted biphenyls has been investigated. Atropisomerism involved in the above ring system has been studied using NMR spectroscopy. The outcome of inter and intramolecular Heck reaction is discussed.     

DPPH (= 2,2‐Diphenyl‐1‐picrylhydrazyl) Radical‐Scavenging Reaction of Protocatechuic Acid (= 3,4‐Dihydroxybenzoic Acid): Difference in Reactivity between Acids and Their Esters

Protocatechuic acid (= 3,4‐dihydroxybenzoic acid; 1 ) exhibits a significantly slow DPPH (= 2,2‐diphenyl‐1‐picrylhydrazyl) radical‐scavenging reaction compared to its esters in alcoholic solvents. The present study is aimed at the elucidation of the difference between the radical‐scavenging mechanisms of protocatechuic acid and its esters in alcohol. Both protocatechuic acid ( 1 ) and its methyl ester 2 rapidly scavenged 2 equiv. of radical and were converted to the corresponding o‐quinone structures 1a and 2a , respectively (Scheme). Then, a regeneration of catechol (= benzene‐1,2‐diol) structures occurred via a nucleophilic addition of a MeOH molecule to the o‐quinones to yield alcohol adducts 1f and 2c , respectively, which can scavenge additional 2 equiv. of radical. However, the reaction of protocatechuic acid ( 1 ) beyond the formation of the o‐quinone was much slower than that of its methyl ester 2 . The results suggest that the slower radical‐scavenging reaction of 1 compared to its esters is due to a dissociation of the electron‐withdrawing carboxylic acid function to the electron‐donating carboxylate ion, which decreases the electrophilicity of the o‐quinone, leading to a lower susceptibility towards a nucleophilic attack by an alcohol molecule.     

Visible-light-induced halogenation of aliphatic CH bonds

Alkyl halides are of particular interests in the areas of pharmaceutical, agrochemical, and material sciences. Direct CH halogenation has been recognized as the most efficient method for the introduction of halogen atoms into organic molecules. This Digest paper highlighted some of the most recent and significant developments in the visible light-promoted halogenation of aliphatic CH bonds.