Copper-catalyzed cyanation of benzyl chlorides with non-toxic K4[Fe(CN)6]

Copper-based catalysts were firstly introduced into the cyanation of benzyl chlorides with non-toxic K₄[Fe(CN)₆]. The presented method avoids the use of extremely poisonous alkali cyanides and precious palladium catalysts. No other reagent apart from CuI, K₄[Fe(CN)₆] and toluene was used in the cyanation, showing that the presented protocol is simple and practical. A series of benzyl chlorides were smoothly cyanated in up to 85% yield under the optimal conditions.     

An expedient Pd/DBU mediated cyanation of aryl/heteroaryl bromides with K4[Fe(CN)6

A practical Pd(PPh(3))(4)/DBU catalytic system for the synthesis of pharmaceutically relevant aminopyridine nitrile intermediates, as well as a variety of other aryl nitriles using non-toxic K(4)[Fe(CN)(6)] has been developed. The key features of our new protocol for cyanation lie in that the reaction can be carried out with readily available Pd(PPh(3))(4) under mild and green conditions, even without the assistance of other ligands.     

Preparation of57Fe enriched K4[Fe(CN)6] and K3[Fe(CN)6]

A simple method to prepare⁵⁷Fe enriched K₄[Fe(CN)₆] and K₃[Fe(CN)₆] is described. The yields of the products are much better than those reported in the literature so far. The enrichment is essential for⁵⁷Fe Mössbauer investigation in a variety of Prussiate type complexes and other inorganic compounds which are conveniently prepared from K₄[Fe(CN)₆] and K₃[Fe(CN)₆]. K₄[Fe(CN)₆] was obtained by reacting freshly prepared Fe(OH)₃ with glacial acetic acid and treating with iron acetate in boiling aqueous solution of KCN. The novel feature of the procedure to obtain K₃[Fe(CN)₆] is that the oxidation of K₄[Fe(CN)₆] has been carried out in the solid state by passing chlorine gas over the powdered specimen. K₃[Fe(CN)₆] was crystallised from alkaline solution of this oxidised powder. The compounds were characterised by Mössbauer spectroscopy.     

A mild and efficient palladium-catalyzed cyanation of aryl chlorides with K4[Fe(CN)6

An efficient palladium-catalyzed cyanation of aryl chlorides is established. In the presence of a highly effective Pd/CM-phos catalyst, cyanation of aryl chlorides proceeds at 70 °C in general, which is the mildest reaction temperature achieved so far for this process. Common functional groups such as keto, aldehyde, ester, nitrile and -NH(2), and heterocyclic coupling partners including N-H indoles are well tolerated. Moreover, a sterically hindered nonactivated ortho,ortho-disubstituted electrophile is shown to be a feasible coupling partner in cyanation.     

Fe L-edge XAS studies of K4[Fe(CN)6] and K3[Fe(CN)6]: a direct probe of back-bonding

Distinct spectral features at the Fe L-edge of the two compounds K3[Fe(CN)6] and K4[Fe(CN)6] have been identified and characterized as arising from contributions of the ligand pi orbitals due to metal-to-ligand back-bonding. In addition, the L-edge energy shifts and total intensities allow changes in the ligand field and effective nuclear charge to be determined. It is found that the ligand field term dominates the edge energy shift. The results of the experimental analysis were compared to BP86 DFT calculations. The overall agreement between the calculations and experiment is good; however, a larger difference in the amount of pi back-donation between Fe(II) and Fe(III) is found experimentally. The analysis of L-edge spectral shape, energy shift, and total intensity demonstrates that Fe L-edge X-ray absorption spectroscopy provides a direct probe of metal-to-ligand back-bonding.     

K4[Fe(CN)6]-K3[Fe(CN)6]体系催化分光光度法测定痕量汞

建立了一种测定痕量汞的催化分光光度新方法,它是基于汞能催化亚铁氰化钾分解生成Fe2 ,生成的Fe2 又与铁氰化钾反应生成兰色胶体溶液.方法的相对标准偏差≤5.3%,回收率为98.8%～104.8%之间,检出限为9.8×10-7 g/L;线性范围为0～0.050 μg/mL.     

Palladium-catalyzed three-component arylcyanation of internal alkynes with aryl bromides and K4[Fe(CN)6

The one-pot, palladium-catalyzed, three-component coupling of aryl bromides, internal alkynes, and environmentally friendly K4[Fe(CN)6] provides an efficient and direct method for the preparation of beta-arylalkenylnitriles.     

Efficient cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by a palladium-indolylphosphine complex

This study describes a general palladium-catalyzed cyanation of aryl bromides using K₄[Fe(CN)₆] as the cyanide surrogate. The reactions can be successfully conducted under mild reaction conditions (at 50 °C) in mixed solvents (water/MeCN = 1:1) without any surfactant additives, and afford the desired aryl nitriles in good-to-excellent yields. Particularly noteworthy is that this system allows the mildest reaction temperature reported so far for palladium-catalyzed cyanation of aryl bromides with K₄[Fe(CN)₆] source in general. Common functional groups, including keto, aldehyde, free amine, and heterocyclic substrates are compatible under this system. Interestingly, the phosphine ligands bearing -PCy₂ moiety, which usually show excellent activity in aryl halide couplings, are found less effective than the corresponding ligands with -PPh₂ group.     

无配体铜催化芳溴和K_4[Fe(CN)_6]的氰化

铜催化芳溴氰化反应通常在惰性气体保护下进行, 而且配体和碱的使用也是必要的. 本文发现无配体的Cu(OAc)_2·H_2O能够有效地催化芳溴的氰化;并且反应无需使用碱, 无需惰性气体保护;为芳腈的合成提供一种经济有效的方法. 此方法可应用到多种芳溴的腈化, 在16种芳溴底物反应的例子中, 得到了56%-94%的产率.     

Local deposition and characterisation of K2Co[Fe(CN)6] and K2Ni[Fe(CN)6] by scanning electrochemical microscopy

Scanning electrochemical microscopy (SECM) is used to form local deposits of different Prussian blue analogs on macroscopic surfaces of gold and glassy carbon. Dissolution of Co and Ni sacrificial ultramicroelectrodes (UMEs) generates divalent cations in the gap between the UME and the macroscopic specimen electrode. Co²⁺ or Ni²⁺ precipitate with [Fe(CN)₆]^4– formed by reduction of [Fe(CN)₆]^3– at the macroelectrode. By moving the UME while generating Co²⁺ or Ni²⁺, lines can be "drawn" with a width of 130 μm. The line width can be adjusted by reagent concentration and translation speed of the UME. Different pulse programs allow the formation of ring-shaped structures. The deposited hexacyanoferrate microstructures show catalytic activity for the reduction of Fe³⁺ which was imaged in the feedback and generation-collection modes of the SECM. Electronic Publication     

Pd-catalyzed cyanation of benzyl chlorides with nontoxic K4[Fe(CN)6]

Non-toxic K₄[Fe(CN)₆] was demonstrated to be effective as a green cyanating agent for the cyanation of alkyl halides using PPh₃/Pd(OAc)₂ as a catalyst system. The presented method allowed a series of benzyl chlorides to be smoothly cyanated in up to 88% yield. In order to avoid or suppress the deactivation of the catalyst, the reaction was required to be performed in a stringent inert ambiance.     

掠射椭偏术对K_4〔Fe(CN)_6〕/K_3〔Fe(CN)_6〕电极反应的研究

提出掠射椭圆偏振测试技术的实验方案,应用该掠射式技术结合循环伏安法研究了在镀有Ｉｎ２Ｏ３玻璃片上进行的Ｋ４〔Ｆｅ（ＣＮ）６〕／Ｋ３〔Ｆｅ（ＣＮ）６〕电极反应．结果证明：掠射椭圆偏振术可在电化学反应过程中现场测定椭圆偏振参数及其变化规律,这些规律与所发生的表面电化学反应规律相对应,由此可以对电极体系进行研究;现场掠射椭圆偏振术还能用于分析表面扩散层的性质,弥补其它界面研究方法的缺陷．     

Ag/Cu-mediated decarboxylative cyanation of aryl carboxylic acids with K4Fe(CN)6 under aerobic conditions

A method for facile synthesis of aryl nitriles has been well established via Ag/Cu-mediated decarboxylative cyanation of benzoic acids with K₄Fe(CN)₆ under aerobic conditions. The approach of using readily accessible aryl carboxylic acids and green K₄Fe(CN)₆ as starting material provides a feasible alternative to previous cyanation protocols. Control experiments revealed the key role of Cu for the process and excluded the possibility of a radical mechanism for the transformation.     

Strukturchemische Untersuchungen von Monammin-Kupfer(I)-Komplexen: [CuNH3]2[Pt(CN)6], [CuNH3]2[Pt(CN)4] und Cu3[Co(CN)6]-2 NH3

Structurally Chemical Investigation of Monoammin Copper (I) Complexes : [CuNH₃]₂[Pt(CN)₆], [CuNH₃]₂[Pt(CN)₄] and Cu₃[Co(CN)₆] · 2NH₃ The preparation and the properties of [CuNH₃]₂[Pt(CN)₆], [CuNH₃]₂[Pt(CN)₄] and Cu₃[Co(CN)₆] · 2NH₃ are described. I.R. and Raman spectra have been recorded and assigned. According to X-ray powder diagrams, [CuNH₃]₂[Pt(CN)₆] crystallizes in the trigonal space group D–P3 ml, a = 7.771, c = 5.988 Å, Z = 1. According to the spectroscopic and crystallographic data, it is concluded that the Cu_I ion is coordinated with one NH₃ group and with the N atoms of the cyanometallate anions. The coordination number of the Cu⁺ is 4 in [CuNH₃]₂[Pt(CN)₆] and 3 in [CuNH₃]₂[Pt(CN)₄]. In the Cu₃[Co(CN)₆] · 2 NH₃ complex two Cu atoms have the coordination number 2, the third Cu atom 4.     

Pd/C: A Recyclable Catalyst for Cyanation of Aryl Halides with K4[Fe(CN)6]

Aryl nitriles have been prepared from the corresponding aryl halides with potassium hexacyanoferrate(II) using Pd/C as a catalyst. No ligand or cocatalyst is required. This protocol also avoids the use of highly toxic alkali cyanides. Furthermore, the catalyst can be recycled via simple filtration and washing sequences.     

MÖSSBAUER- und Infrarotspektren von Addukten des K4[Fe(CN)6] mit Antimontrihalogeniden

Mössbauer- and IR Spectra from the Addition Compounds of K₄[Fe(CN)₆] with Antimony Trihalides By the reaction of K₄[Fe(CN)₆] with SbX₃ in the melt (X = Cl, Br) or in SO₂ solution (X = F) the addition compounds K₄[Fe(CNSbX₃)₆] (X = F, Cl) and K₄[Fe(CNSbX₃)₄(CN)₂] (X = Cl, Br) are formed. The IR spectra of these compounds have been interpreted. The MÖSSBAUER spectra are single lines which exhibit a slight broadening compared with K₄[Fe(CN)₆] · 3 H₂O. The values of the isomer shifts following the order of the LEWIS acid strengths of the SbX₃ molecules correspond to a small but significant increase of the s-electron density, which is explained by the increasing influence of the π-acceptor function of the ligands.     

亚铁氰化钾体系的掠射椭圆偏振技术谱学分析研究

应用掠射式椭圆偏振谱学方法和循环伏安法现场分析不同浓度Ｋ４「Ｆｅ（ＣＮ）６」不同浓度电解液在镀Ｉｎ２Ｏ３玻璃电极上进行的电化学反应，结果表明：当Ｋ５「Ｆｅ（ＣＮ）６」的浓度在１×１０＾－４－１×１０＾－３范围蛤，掠射式椭圆偏振参量Δ的峰值增量与其浓度成正比，而ψ的峰值增量与其浓度近似为指数关系。     

掠射椭圆偏振术对K4[Fe(CN)6]/K3[Fe(CN)6]表面溶液层性质的研究

目前广泛应用于表面反应现场研究的椭圆偏振技术都采用反射式测量方案[1，2]，这种方法通过测量光在电极表面反射时描述偏振光相位变化的参量和振幅变化的参量．以及上述两个参量的变化趋势并结合预先设定的表面膜模型计算表面膜厚度和复折射系数等光学参量[3]反射式椭圆偏振测