1,5—双二茂铁基—4—己烯—1,3—二酮的合成

β-二酮是一类性能良好的螯合剂。化合物的一端引入二茂铁基,可使β-二酮与稀土离子的络合性能有所改变,但它对稀土金属的络合仍然没有选择性。为了寻找对稀土有不同络合能力的β-二酮,从而达到选择性地络合分离稀土的目的,我们首次合成了一种新的β-     

几种β-二酮化合物互变异构体的光谱性质研究

合成了5种不同结构的β-二酮化合物,采用电喷雾质谱、紫外光谱、红外光谱和核磁共振法对其结构进行表征,并讨论了它们的酮式-烯醇式互变异构现象.结果表明,β-二酮分子内酮式-烯醇式的互变异构平衡明显受取代基影响,它们的酮式-烯醇式互变异构体含量完全不同.在固态和CDCl3溶液中,其中2种β-二酮化合物(a1,a2)中主要以烯醇形式存在,仅含有少量的酮式结构;而2种α-取代β-二酮(b1,b2)由于烯醇异构体的空间位阻效应,不能以分子内氢键形成烯醇六元环,全部以酮式结构形式存在;另外,由于强吸电子基团-CF3的作用,使得β-二酮(c)全部以烯醇形式存在.     

双-[一氰乙基化β-二酮基]合铜Ⅱ的合成及其性质

本文通过一氰乙基化β-二酮与醋酸铜作用合成了五个双-[一氰乙基化β-二酮基]合铜(Ⅱ)配合物,并进行了元素定量分析,红外光谱分析、紫外光谱分析,这些配合物是未知的新的配合物。     

几种β-二酮化合物及其互变异构体的光谱

合成了 6种β-二酮化合物 :1 ,3-二 (4 -硝基苯基 ) -1 ,3-丙二酮 ,1 -(4 -硝基苯基 ) -3-(3-硝基苯基 ) -1 ,3-丙二酮 ,1 ,3-二 (3-硝基苯基 ) -1 ,3-丙二酮 ,1 ,3-二 (4 -氨基苯基 ) -1 ,3-丙二酮 ,1 -(4 -氨基苯基 ) -3-(3-氨基苯基 ) -1 ,3-丙二酮和 1 ,3-二 (3-氨基苯基 ) -1 ,3-丙二酮 .采用多种光谱法对其结构进行了鉴定 .测量了不同溶剂中β-二酮化合物的酮式含量 ,给出了酮式 -烯醇式异构化平衡常数和烯醇式异构体的存在比例     

β—二酮或β—三酮对铈（Ⅳ）盐引发烯类单体聚合的影响

研究了β－二酮或β－三酮（如：３－苄基乙酰丙酮，苯甲酰基丙酮，二苯甲酰基甲烷及３－苯甲酰基乙酰丙酮）对铈（Ⅳ）盐引发丙烯酰胺聚合的促进作用，测定了聚合反应速度及表观活化能，表明铈（Ⅳ）盐／β－二酮或β－三酮可组成活性很高的氧化还原体系，采用版自旋捕捉技术及ＥＳＲ谱研究了体系的初系级自由基结构，通过ＦＴＩＲ光谱端基分析检测这类体系引发丙烯腈所得聚合物端基有β－二酮结构，以此为基础，提出了这类体系引发     

两种芳香β-二酮化合物的合成及表征

β-二酮化合物是一类重要的有机合成中间体,β-二酮化合物分子内酮式-烯醇式之间的异构化转变赋予其许多独特的光化学和配位化学性质。关于酮式-烯醇式之间的互变关系有许多研究[1,2,3],借助于其光致互变异构的光化学性质,β-二酮化合物可广泛地用作光稳定等功能材料[4]。同时,     

通过α—重氮—β—二酮与醛酮的环加成反应合成4H—1,3—二恶环已—5—烯 …

研究了α-重氮-β-二酮与各类羰基化合物的环加成反应,合成了一系列4H-1,3-二噁环己-5-烯-4-酮衍生物.     

重氮苯基β-二酮的合成及互变异构体研究

在NaOAc弱碱性条件下,进行偶合反应把重氮基引入到β-二酮分子中,合成了一种新的含重氮苯基β-二酮化合物——重氮苯基[1-(4-对苄氧基苯基)-1,3-二酮],通过红外光谱、紫外光谱、核磁共振氢谱、质谱和元素分析对其结构进行了确证.结构分析表明,这种β-二酮化合物(Ⅰ)在氯仿溶液中是以腙式结构存在,同时存在互变异构,且腙式结构(Ⅲ)与腙式结构(Ⅱ)的物质的量比n(Ⅲ)∶n(Ⅱ)=1∶2.     

β-二酮(HTPP)、邻菲罗啉分别与铕和铽三元配合物的合成、 荧光性能及理论研究

合成了一个新的β-二酮配体1-(2-噻吩基)-3-(对苯乙炔基苯基)-1,3-丙二酮(HTPP), 并用HTPP、邻菲罗啉(phen) 分别与Eu(III)和Tb(III)反应, 生成了两个新的三元稀土配合物Eu(TPP)3phen和Tb(TPP)3phen, 用红外光谱、化学分析、元素分析及热重分析对它们的组成和结构进行了表征. 室温下, 在紫外光激发下Eu(III)和Tb(III)的配合物表现出中心离子的特征荧光发射, 发现β-二酮配体对配合物的荧光有较大影响, 通过量子化学计算从理论上对实验结果进行了解释.     

通过α-重氮-β-二酮与醛酮的环加成反应合成4H-1,3-二噁环己-5-烯-4-酮衍生物

研究了α-重氮-β-二酮与各类羰基化合物的环加成反应,合成了一系列4H-1,3-二噁环己-5-烯-4-酮衍生物.     

Photostabilizing activity of tertiary hindered amines

The influence of the N-alkyl group of tertiary hindered amines on the photostabilization of polymers was studied. The photostabilizing effects of the tertiary amine derivatives of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine ( 1a ) in polypropylene were compared. All tertiary amine derivatives having α-H to hindered N showed higher effectiveness than 1a . Model liquid phase photoxidations were carried out by irradiating (UV-lamp) the solutions of tertiary hindered amines containing tert-butyl hydroperoxide as a photoinitiator. The tertiary hindered amines were oxidized more easily than corresponding parent hindered amine and converted to the parent amine, which was identified as its salt, resulting from the carboxylic acid produced from the N-alkyl group by oxidation. The thermal reaction of the tertiary hindered amines with tert-butyl hydroperoxide was also studied in the liquid phase. The tertiary hindered amines decomposed tert-butyl hydroperoxide more rapidly than the parent secondary hindered amine, and generated the parent amine. It was also found that the photostabilizing effects of tertiary hindered amines for polyolefins were higher than that of the parent secondary hindered amine.     

Synthesis of highly substituted cyclohexenes via mixed Lewis acid-catalyzed Diels-Alder reactions of highly substituted dienes and dienophiles

[reaction: see text] A high-yielding method is described for the rapid synthesis of very hindered cyclohexenes by the Diels-Alder reaction of hindered silyloxy dienes and dienophiles using the mixed Lewis acid catalyst system (AlBr(3)/AlMe(3)). Thus, reaction of the hindered diene 4 with various substituted enones gave good yields of the expected cycloadducts even though both partners are quite sterically hindered.     

Photo-stabilisation of polypropylene by a hindered piperidine compound: Influence of hydroperoxide and carbonyl groups

The influence of prior thermally generated hydroperoxides and added benzophenone on the photo-stabilising action of a hindered piperidine compound, bis[2,2,6,6-tetramethyl-4-piperidinyl]-sebacate, in polypropylene film has been examined. The hindered piperidine compound was found to effectively inhibit both the hydroperoxide and carbonyl group sensitised photo-oxidation of the polymer. Using ESR spectroscopy, evidence is presented to show that the hindered piperidine compound reacts stoichiometrically with the hydroperoxide groups generated by thermal oxidation to give a stable nitroxyl radical. The photo-stabilising effects observed are discussed in relation to our understanding of the ultraviolet anti-oxidant action of the hindered piperidine systems.     

Microwave-assisted, zinc-mediated peptide coupling of N-benzyl-α,α-disubstituted amino acids

Incorporation of the extremely hindered amino acid N-benzylaminoisobutyric acid into dipeptides under microwave irradiation with commercial zinc dust is described. A comparative survey of various methodologies for hindered peptide couplings was undertaken. The optimised coupling conditions were free from racemisation and applicable to other hindered amino acids.     

A Simple Method for the Synthesis of the Sterically Hindered Chloramines

A simple route to the hindered chloramines, starting from the corresponding hindered amines is reported. Sodium dichlorisocyanurate is the chlorinating agent.     

Photo-stabilising performance of a hindered piperidine compound in polypropylene film: Anti-oxidant/light stabiliser effects

The effect of various primary and secondary anti-oxidants and light stabiliser systems on the photo-stabilising performance of a hindered piperidine compound bis[2,2,6,6-tetramethyl-4-piperidinyl]-sebacate, in polypropylene film has been examined. None of the anti-oxidants or light stabilisers gave an additive effect with the hindered piperidine compound. In many cases antagonistic effects were observed. The effects observed are discussed in relation to our current understanding of the mechanistic behaviour of these hindered piperidine systems.     

乙烯系单体自由基聚合的阻聚效应——Ⅸ.受阻胺-醌类电荷转移络合物对甲基丙烯酸甲酯自由基聚合的阻聚及历程

用膨胀计法研究了西氯苯醌(CA)、苯醌(BQ)与受阻胺二异丙胺(DIPA)、2,2,6,6-四甲基-4-羟基哌啶(TMP)形成的电荷转移络合物(CTC)对偶氮二异丁腈(AIBN)引发的甲基丙烯酸甲酯(MMA)自由基聚合阻聚效应。结果表明,CA-DIPA、CA-TMP、BQ-DIPA和BQ-TMP对MMA的自由基聚合均产生较单独的醌或胺更显著的阻聚能力。其中以CA-DIPA阻聚效果更佳。比较了MMA在苯或乙腈中的溶液聚合,得类似结果。初步讨论了受阻胺-醌电荷转移络合物对MMA自由基聚合的阻聚反应机理。     

Synthesis of Sterically Hindered Heteroaromatic Ketones under Phase-transfer and Metal-complex Catalysis Conditions. (Review)

We have correlated data on methods for obtaining sterically hindered ketones, derivatives of furan, thiophene, pyrrole, and pyridine. We examine routes to arylation of chroman-4-ones and synthesis of sterically hindered unsaturated and silicon-containing heteroaromatic ketones.     

NBS-Promoted reactions of symmetrically hindered methylphenols via p-benzoquinone methide

Symmetrically hindered methylphenols 1 react smoothly with NBS to form transient intermediates, p-benzoquinone methides (BM), which can be further processed to give hydroxybenzaldehydes in the presence of DMSO. This reaction is initiated by the formation of the phenoxy radical, followed by disproportionation to afford BM. None of the side-chain-brominated product is observed. The existence of BM is supported by the following observations: the formation of BM in solution can be monitored by GC and GC-MS; the electrophilic methine part participates in electrophilic aromatic substitution with anisoles to give hydroxybenzylated products 15; and the double bond character of the exocyclic methine plays a role in [4 + 2] cycloaddition with diene to afford Diels-Alder adducts. In contrast, unsymmetrically hindered or simple methylphenol (p-cresol) with NBS gives the nuclear brominated products, as usual. The energies of symmetrically hindered BMs, unsymmetrically hindered BM, and simple BM were calculated using density functional theories. Relative stabilization energies calculated at the B3LYP/6-31G//B3LYP/6-31G level by an isodesmic equation are enhanced 3-6 kcal/mol for symmetrically hindered BMs.     

Photostabilizing activity of N-acylated hindered amine

The influence of the acyl groups of N-acylated hindered amine on the photostabilization of polymers was discussed. The effects of the N-acyl derivatives of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine ( 6 ) in the photostabilization of polypropylene were compared. Although the stabilizing effects of all the N-acyl derivatives were lower than that of the N-oxyl derivative ( 7 ), N-acryloyl ( 4 ) and N-benzoyl ( 5 ) derivatives showed higher effects than that of parent N? H 6 . To discuss the stabilizing mechanism of N-acylated hindered amine, the reaction of N-acylated hindered amine with model hydroperoxide (tert-butyl hydroperoxide) was carried out at an elevated temperature (132°C). N-Acylated hindered amine decomposed tert-butyl hydroperoxide more rapidly than corresponding secondary hindered amine, and changed into the parent secondary amine.