Sigma-Pi Rearrangements of Organotransition Metal Compounds

σ-Bonded organic groups in transition-metal complexes can rearrange to π-bonding ligands and vice versa: the classic example is the formation of π-arenechromium complexes from σ-arylchromium compounds. Rearrangements of this kind can be induced, inter alia, by reactions of the metal or of the ligand, as well as by migration or insertion of a ligand. Rearrangements play a role in many industrial processes, including the polymerization and isomerization of olefins and the hydroformylation of olefins.     

Skeletal Rearrangements of Organoalkali Metal Compounds

Organometallic compounds of the alkali metals undergo concerted [1,n] sigmatropic migration of aryl, vinyl, carbonyl, alkoxycarbonyl, silyl, germyl, and related groups. Sigmatropic migration of alkyl, benzyl, and hydrogen occur only under special circumstances and then may occur by an alternate fragmentation-recombination pathway. Allyl groups may migrate by the latter process or by a concerted [2,3] sigmatropic reaction. These molecular rearrangements are discussed from the viewpoint of simple molecular orbital theory. By suitable choice of the alkali metal, temperature, ligands of the alkali cation and/or the solvent, considerable control may be exercised over the rate of rearrangement, the relative migratory aptitude of groups, and the mechanistic pathway.     

Spectroscopic Properties of Organic Azo Compounds

Azo compounds are characterized by a low-energy ¹(n,π^*) electronic state, which gives rise to a weak band at long wavelengths in the absorption spectrum. Coupling of this state with other low-lying molecular states is responsible for the high intensity of the “azo band” compared to other forbidden transitions, for its lack of vibrational structure, and for the inability of nearly all organic azo compounds to fluoresce.     

多烯化合物的Cope重排反应:[5,5]σ迁移、串联[3,3]σ迁移与自由基重排机理

介绍戊二烯基苯基醚和1,3,7,9-癸四烯衍生物重排反应的机理。戊二烯基苯基醚的重排反应是经过[5,5]和串联的[3,3]σ迁移反应双途径进行的;而1,3,7,9-癸四烯衍生物重排反应既可以经过[5,5]和串联的[3,3]σ迁移反应双途径进行,也可以经过自由基机理进行。     

催化脱氢法合成新型偶氮化合物

催化脱氢法合成新型偶氮化合物王彩兰王玉炉王晓阳李建平王红马东兰（河南师范大学化学系新乡４５３００２）偶氮化合物是一类重要的有机化合物，它被广泛用作染料和分析试剂，还能用于现代科技中的非线性光学材料、油溶性染料等［１］。近来许多研究表明，偶氮苯类衍生物...     

吡啶酮系偶氮类化合物可见吸收光谱的预测

利用密度泛函的B3LYP方法, 在6-311G*基组水平对吡啶酮系偶氮类化合物进行构型优化, 并进行了自然键轨道(NBO)分析, 然后用TDDFT方法和ZINDO/S方法分别计算了它们的可见吸收光谱, 结果均与实验值十分吻合. 通过对比发现, 对于最高吸收波长的计算, ZINDO/S能以较快的速度得到较好的结果. 在用ZINDO/S计算的过程中, 回归分析发现π-π重叠加权因子(OWF_π-π)与染料分子吡啶环上两个羰基氧原子平均电荷Z_O有较好的线性关系: OWF_π-π＝0.11425－1.04178ZO, 这一关系不仅可从量子化学的角度进行解释, 而且可用于同类染料可见吸收光谱的预测. 分子轨道的研究表明, 这些化合物的最高可见吸收波长主要对应着共轭体系中给电子体到受电子体的电子跃迁.     

Electrochemical Behavior of Azo Compounds in Liquid Ammonia

Abstract

At -40°C, the behavior of lO compounds, differing widely in their standard potentials, has been investigated in liquid ammonia, using cyclic voltammetry at a smooth platinum electrode. The purpose of this study was the realization of a redox scale with reversible systems. With azobenzene, pyridazine, cin-noline, benzocinnoline and 4,4′-azobis-(pyridine-N-oxide), the first electron transfer is reversible and leads to the formation of the corresponding radical anions which are stable; the second electron transferleads to the ciianions which can be protonated yielding the corresponding hydrazo. Other compounds, such as azoxybenzene, 3-amino-1,2,4-triazine, pyridine-N-oxide, 8-azaadenine and 1H-tetrazole, have an electrochemical behavior which i s more intricate.     

A New Method for Preparing Amine Azo Compounds

In previous work, we have found that DMF is a good absorbent of NO₂, The resulting product DMF-NO₂ can be used as a mild and selective oxidant to oxidize acetals and oximes to corresponding aldehydes or ketones. Now,we find that it is also effective to covert substituted aniline compounds into corresponding amino azo compounds.     

Lead-Catalyzed Synthesis of Azo Compounds by Ammonium Acetate Reduction of Aromatic Nitro Compounds

Abstract

Lead/ammonium acetate is a convenient reagent for the reduction of aromatic nitro compounds to the corresponding symmetrically substituted azo compounds. Various azo compounds containing additional reducible substituents such as halogen, nitrile, acid, phenol, ester, methoxy, etc., functions have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol.     

芳香偶氮化合物的合成研究进展

综述了芳香偶氮化合物的主要合成方法,包括重氮偶联反应、米尔斯反应、胺的氧化、芳肼的的氧化、硝基化合物的还原偶联反应、重氮盐的二聚反应、叠氮化合物的热解等,并对各方法的优缺点进行了简要评述。     

Reductive Cleavage of Azo Compounds by Zinc and Ammonium Chloride

Abstract

Azo compounds are reduced to corresponding anilines with zinc dust in the presence of ammonium chloride in methanol at room temperature.     

Dehydrogenation of Unsymmetric Hydrazo Compounds in Ionic Liquid: Novel Green Synthesis of Azo Compounds

Using NBS (N‐bromosuccinimide) and the ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate) as an oxidation system, twelve unsymmetric azo compounds were efficiently prepared from hydrazo compounds for the first time. In contrast to the known methods, this novel access to azo compounds presented here is operationally simple, environmentally benign and has the advantage of enhanced atom utilization. Furthermore, the solvent and the basic catalyst used can be recovered conveniently and reused efficiently.     

相转移催化法合成新型偶氮化合物

由β－苯丙烯酰氯与取代苯肼的综合反应合成了芳基取代的α,β－不饱和酰肼化合物,进而利用相转移催化剂４－羟基－２,２,６,６－四甲基－１－哌啶基氧自由基以及Ｇａｌｖｉｎｏｘｙｌ自由基对基进行了相转移催化脱氢,合成了８种芳基取代的α,β－不饱和酰基偶氮新型化合物,其结构经元素分析、ＩＲ和＾１ＨＮＭＲ证实,并讨论了可能的反应机理。     

A Convenient Solid State Method for Preparing Aryl Azo Compounds

A convenient solid state reaction using ferric nitrate to oxidize substituted semicarbazide for preparing azo ureas has been reported for the first time. Eight phenyldiazenecarboxylic acid anilide derivatives, have been synthesized in excellent yields with cheap reagents and simple instruments under room temperature.     

基于环糊精和偶氮化合物的光控可逆超分子体系

超分子化学是当前化学领域的研究热点之一。基于环糊精和偶氮化合物的光控超分子可逆体系是近几年在超分子化学基础上发展起来的活跃领域。二者的复合物具有的优秀光学性质使其在光敏型自组装、催化、分子机器设计和智能材料领域受到极大的关注。本文综述了基于环糊精和偶氮化合物的光控超分子可逆体系的研究进展。介绍了该体系的研究背景、优势与原理; 根据该体系控制组装体的不同进行了分类总结,包括囊泡、凝胶、轮烷、催化体系、分子触手等; 最后结合现阶段的研究情况,对其前景与发展方向进行了展望。     

A Simple and Efficient Method for the Reduction of Azo Compounds

Abstract

Reduction of azo compounds using hydrazine hydrate as reducant without catalyst is described, which proceeded smoothly in mild condition and did not pollute the environment.     

The Chemistry of α-Carbonyl Azo Compounds

α-Carbonyl azo compounds such as diesters of azodicarboxylic acids, diacylazo compounds, and esters of arylazocarboxylic acids are highly reactive. They add e.g. to amines, aromatic compounds, olefins, CH acids, Grignard and diazo compounds, aldehydes, ketones, and ketenes. These reactions can be used for the preparation of triazanes, hydrazones, oxa-diazoline, azomethinimine, and diazetidine derivatives, etc. α,α′-Dicarbonyl azo compounds are among the strongest dienophiles known.