Studies on synthesis and kinetics of thermodecomposition of the nickel(Ⅱ) compounds with Schiff base derived from amino acids

Monoaqua salicylaldehyde-o-aminobenzoic acid Ni(Ⅱ) monohydrate (cp1) and monoaqua o-vanillin-o-aminobenzoic acid Ni(Ⅱ) monohydrate (cp2) were synthesized. The composition and structures of these two compounds were analyzed. Their thermal stability and non-isothermal kinetics were also investigated by use of TG and DTG curves. The possible reaction mechanisms in their first steps of thermal decomposition reactions were deduced by means of integral and differential methods. Thermodecomposition kinetic equations of the compounds are as follows:Cp1: da/At = A . exp(-E/RT) . 3/2(1 - a)4/3 . [1/(1 - a)1/3 -1]-1 Cp2 : da/At = A . exp(-E/RT) . (1 - a)     

Novel heterocyclic Tröger's base derivatives containing N-methylpyrrole units

Novel analogues of Tröger's base were prepared regioselectively from 4-amino-N-methylpyrrole carboxylates in good yield. Catalytic hydrogenation of dibenzyl-4,9-methano-1,6-dimethyl-4,5,9,10-tetrahydro-1H,6H-dipyrrolo-[3,2-b:3′,2′-f][1,5]diazocin-2,7-dicarboxylate 2b led to 4,9-methano-1,6-dimethyl-4,5,9,10-tetrahydro-1H,6H-dipyrrolo-[3,2-b:3′,2′-f][1,5]diazocin-2,7-dicarboxylic acid 3 which was used for the preparation of Tröger's base derivatives of natural antibiotics via an amide protocol. The novel heterocyclic Tröger's bases were characterized by a variety of spectroscopic techniques and compound 2b by X-ray crystallography. Incorporation of guanidine as the terminal group in the N-methylpyrrole Tröger's base skeleton opens the possibility for preparation of water soluble derivatives.     

A novel ion selective membrane potentiometric sensor for direct determination of Fe(III) in the presence of Fe(II)

A new PVC membrane potentiometric sensor that is highly selective to Fe(III) ions was prepared by using 2-[(2-hydroxy-1-propenyl-buta-1,3-dienylimino)-methyl]-4-p-tolylazo-phenol [HPDTP] as a suitable carrier. The electrode exhibits a linear response for iron(III) ions over a wide concentration range (3.5 × 10⁻⁶ to 4.0 × 10⁻²) with a super Nernstian slope of 28.5 (±0.5) per decade. The electrode can be used in the pH range from 4.5 to 6.5. The proposed sensor shows fairly a good discriminating ability towards Fe³⁺ ion in comparison to some hard and soft metals such as Fe²⁺, Cd²⁺, Cu²⁺, Al³⁺ and Ca²⁺. It has a response time of <15 s and can be used for at least 2 months without any measurable divergence in response characteristics. The electrode was used in the direct determination of Fe³⁺ in aqueous samples and as an indicator electrode in potentiometric titration of Fe(III) ions.     

Copper(II) Complexes of ω‐Hydroxy‐Functionalized N‐Salicylidenehydrazides show pH‐Controlled Switching between Dicationic Dimers and Neutral One‐Dimensional Coordination Polymers

New copper(II) complexes of the hydrazone ligands H₂salhyhb, H₂salhyhp, and H₂salhyhh, derived from salicylaldehyde and ω‐hydroxy carbonic acid hydrazides, have been synthesized and physically characterized. Two fundamental structures were found in solid state depending on the pH‐value of the reaction solution. Acidic conditions lead to the formation of the di‐μ‐phenoxo‐bridged dicationic complex dimers [{Cu(Hsalhyhb)}₂]²⁺ ( 1a ), [{Cu(Hsalhyhp)}₂]²⁺ ( 2a ), and [{Cu(Hsalhyhh)}₂]²⁺ ( 3a ), isolated as perchlorate salts. The dimeric complexes show strong antiferromagnetic coupling with J = ?399 ( 1a ), ?410 ( 2a ), and ?311 cm^?1 ( 3a ). Higher pH‐values resulted in the aggregation of neutral copper ligand fragments to the one‐dimensional coordination polymers [{Cu(salhyhb)}_n] ( 1b ), [{Cu(salhyhp)}_n] ( 2b ), and [{Cu(salhyhh)}_n] ( 3b ). 3b has been examined by means of X‐ray crystallography and represents the first example of a structurally characterized neutral copper(II) N‐salicylidenehydrazide complex without additional ligands. The magnetic interactions in the polymers are also antiferromagnetic with J = ?125 ( 1b ), ?136 ( 2b ), and ?148 cm^?1 ( 3b ), but strongly reduced compared to the corresponding dimeric complexes. The two basic structure types can be reversibly interconverted simply by pH‐control.     

A cobalt(II)-selective PVC membrane based on a Schiff base complex of N,N′-bis(salicylidene)-3,4-diaminotoluene

A new PVC membrane electrode for Co²⁺ based on N,N′-bis(salicylidene)-3,4-diaminotoluene, an excellent neutral carrier, has been fabricated using sodium tetraphenylborate (NaTPB) as an anionic excluder and dioctylphthalte (DOP) as a solvent mediator. The electrode exhibits a linear potential response in the concentration range of 7.9 × 10⁻⁸ to 1.0 × 10⁻¹ M with a slope of 30 ± 0.2 mV per decade. The detection limit of the proposed sensor is 5.0 × 10⁻⁸ M and it can be used over a period of 5 months. The proposed sensor revealed good selectivity over a wide variety of other cations including alkali, alkaline earth, heavy and transition metals and could be used in the pH range of 2.0-9.0. This electrode was successfully applied for the determination of Co²⁺in real samples and as an indicator electrode in potentiometric titration of cobalt ions.     

Aza-Morita-Baylis-Hillman reactions of N-(benzylidene)polyfluoroanilines with methyl acrylate and acrylonitrile

Aza-Morita-Baylis-Hillman reactions of N-(benzylidene)polyfluoroanilines 1 with methyl acrylate or acrylonitrile were studied. It was found that Lewis base, solvent and reaction temperature can significantly affect the reaction. Using 3-hydroxyquinuclidine (3-HQD) as a Lewis base in the reactions of 1 with methyl acrylate in DMF, the normal aza-Morita-Baylis-Hillman adducts 3 were formed in moderate to excellent yields. For the reactions of 1 with acrylonitrile, 1,4-diazabicyclo[2.2.2]octane (DABCO) is the best Lewis base giving the corresponding aza-Morita-Baylis-Hillman adducts 4 as the sole product in good to moderate yield. However, upon treatment of 1 with acrolein 2c, the corresponding reaction did not occur even in the presence of a variety of catalysts.     

含吗啉基片段的水杨醛席夫碱类化合物的合成及其淬灭1,1-二苯基-2-三硝基苯肼自由基性能

通过3-氟-4-吗啉基苯胺和取代水杨醛缩合反应,合成了14个含吗啉基片段水杨醛席夫碱类化合物(Ⅰa-Ⅰn)。通过核磁共振波谱仪(NMR)、傅里叶变换红外光谱仪(FTIR)、液相色谱-质谱联用仪(LC-MS)和元素分析等技术手段研究了产物的结构和淬灭1,1-二苯基-2-三硝基苯肼(DPPH)自由基的活性。 结果表明,在0.02~0.10 g/L,所有化合物均表现出一定的淬灭DPPH自由基活性。 其中,化合物Ⅰd和Ⅰf表现出较为优异的性能,化合物Ⅰd的活性在30%~55%,化合物Ⅰf的活性则大于50%。 随着化合物Ⅰd、Ⅰh、Ⅰj和Ⅰn质量浓度的增大,其淬灭DPPH自由基的活性均呈现增强趋势。     

A mild and efficient cyanosilylation of ketones catalyzed by a Lewis acid-Lewis base bifunctional catalyst

A new family of bifunctional catalysts (N-oxides-Ti(OⁱPr)₄ (2:1)) containing a Lewis acid and a Lewis base was developed and applied to the catalytic cyanosilylation of ketones. Utilizing rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex as catalysts, the cyanosilylation products were obtained in 42-97% yield. Based on experimental phenomena and kinetic studies, a catalytic cycle was proposed to explain the remarkable activities of these catalysts. Investigations indicated that rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex should promote the reaction via a dual activation of the ketone by the titanium and TMSCN by the N-oxide.     

Schiff碱配合物的研究——Ⅸ.表面Schiff碱配合物对H2O2分解的催化作用

制备了两种表面Schiff碱及其Cu²⁺、Co²⁺、Ni²⁺、Zn²⁺配合物,考察了它们对H₂O₂分解的催化性能,其活性顺序为:Co²⁺>Cu²⁺>Ni²⁺>Zn²⁺,且与金属离子氧化还原电位有关。溶液的pH值增加有利于催化反应,有机配体的加入则对反应有所抑制。     

溶剂在丁腈基聚氨酯中的溶解和扩散

用石英弹簧法和示差扫描量热法 (DSC)、红外分光光度计 (FTIR)研究了苯、乙醇、丙酮、醋酸乙酯和1,2 二氯乙烷五种溶剂在端羟基聚丁二烯 丙烯腈共聚物为软段的聚氨酯中的溶解和扩散行为 .结果表明所有溶剂在丁腈聚氨酯中的扩散均为非费克扩散 ,且随着溶剂蒸汽压增大偏离费克扩散的程度增大 .相同相对蒸汽压下 1,2 二氯乙烷和醋酸乙酯偏离费克 (Fickian)扩散的程度较大 ,而乙醇、丙酮和苯则较小 ,这主要与它们和丁腈软段溶解度参数的极性分量和氢键分量有关 .1,2 二氯乙烷和苯在HTBN PU中的溶解度较高 ,而乙醇 ,醋酸乙酯和丙酮较低 ,主要与它们和丁腈软段溶解度参数的色散分量有关 .所有溶剂均表现出近似Flory Huggins型等温吸收曲线 .红外表明吸收溶剂后 ,氨基甲酸酯基团的氢键化程度有不同程度的下降 ,和溶剂与之形成氢键的能力大小有关 .力学性能表明非极性溶剂苯对材料的力学性能影响较小 ,而乙醇 ,醋酸乙酯和丙酮由于可与氨酯基团形成氢键 ,对原HTBN PU中氨酯键氢键的破坏大 ,力学性能下降大