Practical and efficient synthesis of perfluoroalkyl iodides from perfluoroalkyl chlorides via modified sulfinatodehalogenation

A novel two-step one pot synthesis of perfluoroalkyl iodides (α,ω-diiodoperfluoroalkanes) from perfluoroalkyl chlorides (α-chloro-ω-iodoperfluoroalkanes) has been developed by initial conversion to the corresponding sodium perfluoroalkanesulfinates with sodium dithionite and then subsequent oxidation by iodine.     

Synthesis and characterization of a new class of polyfluorinated alkanes: tetrakis(perfluoroalkyl)alkane

The synthesis and physico-chemical characterization of 1,1,2,2-tetrakis(perfluoroalkyl-methylene)ethane {[F(CF₂)_nCH₂]₂CH}₂ (n=6, TK6; n=8, TK8) are reported. The synthesis consists of four steps: (1) addition of allyl alcohol to a perfluoroalkyl iodide, F(CF₂)_nI (n=6,8) to give the corresponding iodo-adduct; (2) dehalogenation of the adduct by treatment with zinc in aqueous acetic acid, yielding 3-perfluoro-n-alkyl-1-propene; (3) addition of 3-perfluoro-n-alkyl-l-propene to perfluoroalkyl iodide, F(CF₂)_nI (n=6,8) to give 1,3-perfluoro-n-alkyl-2-iodo-propane; (4) coupling of 1,3-perfluoro-n-alkyl-2-iodo-propane by zinc in acetic anhydride giving the final products. TK6 and TK8 are characterized by very low surface tension values and exhibit very good properties as potential ski-waxes.     

Stereoselective synthesis of 2-iodo-1-perfluoroalkyl-2(Z)-alkenes and E or Z-4-perfluoroalkylmethyl-4-en-2-ynol via Na2S2O4-promoted radical addition reaction of perfluoroalkyl iodides with allenes and the palladium-catalyzed kinetic resolution with Sonogashira coupling reaction

A Na₂S₂O₄-promoted radical addition reaction of perfluoroalkyl iodides with allenes has been studied in which a Z/E mixture of 2-iodo-1-perfluoroalkyl-2-alkenes 3 were afforded in 52-69% yields. A kinetic resolution using Sonogashira coupling reaction in MeCN using Et₂NH as the base was developed to synthesize the 2-iodo-1-perfluoroalkyl-2(Z)-alkenes (Z-3) and E-4-perfluoroalkylmethylalk-4-en-2-ynols (E-5) stereoselectively. A complete Sonogashira coupling procedure in Et₂NH at 40 °C was also developed affording a mixture of E and Z-4-perfluoroalkylmethyl-4-en-2-ynols (E-5 and Z-5), which may be easily separated by chromatography on silica gel.     

Palladium-catalyzed Heck reaction of in-situ generated benzylic iodides and styrenes

A palladium-catalyzed Heck reaction of in-situ generated benzylic iodides and styrenes has been achieved. The reaction proceeds in a one-pot manner through 1) addition perfluoroalkyl iodides to styrenes to give benzylic iodides, 2) followed by a palladium-catalyzed Heck coupling of the resulting benzylic iodides with the same alkenes in high regio- and stereoselectivity. A variety of perfluoroalkylated alkenes were obtained in moderate to excellent yields.     

A metal-free three components procedure for the synthesis of perfluoroalkyl substituted amidines

An interesting multicomponent reaction for the synthesis of perfluoroalkyl substituted amidines has been developed. By using perfluoroalkyl iodides, tert-butyl isocyanides and amines as the substrates, the reactions proceed via somophilic isocyanide insertion. In this catalytic system, no transition-metal catalyst, additional ligands and additives were required. The reaction proceed smoothly and a variety of desired amidines were obtained in moderate to excellent yields.     

Labeling of alprenolol with fluorescent aryl iodide as a reagent based on Mizoroki-Heck coupling reaction

A novel fluorescent labeling method for alprenolol was developed based on Mizoroki-Heck coupling reaction. We designed and synthesized fluorescent aryl iodide, 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIBI) as a labeling reagent. DIBI has a lophine skeleton carrying an iodide atom acting as fluorophore and reactive center, respectively. In order to evaluate the usefulness of DIBI, a high-performance liquid chromatography (HPLC) with fluorescence detection method was developed for the determination of alprenolol as a model compound of terminal double bond. The fluorescent labeling of alprenolol with DIBI was achieved in the presence of palladium acetate as a catalyst, and the labeled alprenolol was detected fluorometrically. In addition, it was found that the fluorescence of DIBI derivative increased and red shifted when compared with that of DIBI. Furthermore, the proposed method could be applied to determine the alprenolol concentration in rat plasma after administration of alprenolol without interferences from biological components. The detection limit (S/N=3) for alprenolol in rat plasma was 0.74 ng/mL (30 fmol on column).     

Triphenylphosphine chalcogenides as efficient ligands for room temperature palladium(II)-catalyzed Suzuki-Miyaura reaction

A simple catalytic system based on PdCl₂ and triphenylphosphine chalcogenides (PPh₃X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine.     

Visible-light-induced dearomative spirocyclization of N-benzylacrylamides toward perfluorinated azaspirocyclic cyclohexadienones

A feasible approach to 2-azaspirocyclic cyclohexadienones via visible-light-induced perfluoroalkylation cyclization of N-benzylacrylamides was reported. Using R_f-X (X = I or Br) as the R_f radical source, the reaction underwent a cascade radical addition/dearomative cyclization process by Ir photocatalyst, leading to various 2-azaspiro[4.5]deca-6,9-diene-3,8-diones bearing perfluorinated groups including CF₃, n-C₃F₇, n-C₄F₉, n-C₆F₁₃, n-C₈F₁₇, n-C₁₀F₂₁, CH₂CF₂ and CF₂CO₂Et.     

Copper-free Sonogashira coupling reactions catalyzed by a water-soluble Pd-salen complex under aerobic conditions

The water-soluble Pd-salen complex, palladium(II) N,N′-bis{[5-(triphenylphosphonium)methyl]salicylidene}-1,2-ethanediamine chloride, is a highly active catalyst for the copper-free Sonogashira coupling of aryl iodides with terminal alkynes in water under aerobic conditions.     

Applications of a monomeric orthopalladate complex containing mixed phosphorus-nitrogen donors in the Heck reaction

The [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] monomeric orthopalladate complex of homoveratrylamine and triphenylphosphine was synthesized and its application in Heck coupling reactions was investigated. This complex had been demonstrated to be more active than the corresponding dimeric catalyst for Heck reactions of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields using catalytic amounts of [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] as a thermally stable and oxygen insensitive complex in NMP at 130 °C.     

Synthesis of novel perfluoroalkyl-containing polyethers

The synthesis of iodo(perfluoroalkyl)epoxides by radical addition of perfluoroalkyl iodides to allyl glycidyl ether and 1,2-epoxydec-9-ene is described. Dehydroiodination of additional products upon treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gives unsaturated products. The use of Bu₃SnH/Bz₂O₂ as a reduction reagent of iodo(perfluoroalkyl)allyl glycidyl ethers allows to save oxirane ring. Cationic polymerization of saturated or functional (with iodine or double bond) fluoroalkyl oxiranes under action of catalytic amount of BF₃^.Et₂O proceeds only on epoxide group. In case of poly(9-iod-10-(perfluoroalkyl)-1,2-epoxyalkane) iodine atoms are removed by standard zinc reduction.     

An efficient one-step synthesis of 1,4-dihydropyridines via a triphenylphosphine-catalyzed three-component Hantzsch reaction under mild conditions

An efficient one-step synthesis of 1,4-dihydropyridines in good to excellent yields via the triphenylphosphine-catalyzed Hantzsch three-component reaction of an aromatic aldehyde, ethyl acetoacetate and ammonium acetate is described.     

Gallium-induced Barbier coupling of carbonyl compounds with allyl iodide

Gallium metal readily prompted the allylation of aldehydes and ketones with allyl iodide. α, β-Unsaturated carbonyl compounds underwent only 1,2-addition.     

A diphenylphosphinoethane-functionalized polystyrene resin-supported Pd(0) complex as an effective catalyst for copper-free Sonogashira coupling reactions under aerobic conditions

A polymer-supported palladium(0) diphenylphosphinoethane complex was found to be a highly active catalyst for the copper-free Sonogashira coupling reaction of aryl iodides with terminal alkynes, giving excellent yields of products (85-98%) under aerobic conditions.     

火焰原子吸收光谱法间接测定非金属材料中氯

报道了火焰原子吸收光谱法（ＦＡＡＳ）间接测定非金属材料中氯的方法，采用ＡｇＣｌ沉淀，测定剩余Ａｇ~＋间接求出氯含量。方法的特征浓度为０．０１４ｍｇ／Ｌ（１％吸收），检出限为０．０３２ｍｇ／Ｌ（３），测定下限为０．１１ｍｇ／Ｌ，相对标准偏差（ＲＳＤ）为１．５％～１０％，样品加标准回收率在９１．４％－１０５％之间。     

Indium-mediated radical addition of perfluoroalkyl iodide in water

Reaction of perfluoroalkyl groups with carbon-carbon unsaturated compounds using indium in water proceeded smoothly to provide the addition products in high yields.     

高活性和高稳定性的核壳结构PtPx@Pt/C催化氧还原

在质子交换膜燃料电池中,金属铂是最高效的阴极氧还原催化剂之一,但是铂昂贵的价格严重阻碍了其在燃料电池领域中的大规模商业化应用.通过铂与3d过渡金属(Fe、Co和Ni)合金化可以有效提高催化剂的氧还原活性,然而在实际的高腐蚀性、高电压和高温的燃料电池运行环境中,铂合金纳米粒子易发生溶解、迁移和团聚,从而导致催化剂耐久性差.同时过渡金属离子的溶出会影响质子交换膜的质子传导,并且一些过渡金属离子会催化芬顿反应,产生高腐蚀性?OH自由基,加快Nafion和催化剂的劣化.与过渡金属掺杂相比,非金属掺杂具有明显优势:一方面,非金属溶出产生的阴离子不会取代Nafion中的质子,也不会催化芬顿反应;另一方面,与3d过渡金属相比,非金属具有更高的电负性,其掺杂很容易调节Pt的电子结构.因此,本文通过非金属磷掺杂合成具有优异稳定性的核壳结构PtPx@Pt/C氧还原催化剂.通过热处理磷化商业碳载铂形成磷化铂(PtP2),经由酸洗处理产生富铂壳层,即PtPx@Pt/C.X射线粉末多晶衍射结果证明了PtP2相的存在,并且进一步通过电子能量损失谱对纳米粒子进行微区面扫描分析以及X射线光电子能谱分析证实了富铂壳层的存在,壳层厚度约1 nm.得益于核壳结构及磷掺杂引起的电子结构效应,PtP1.4@Pt/C催化剂在0.90 V(RHE)时的面积活性(0.62 mA cm–2)与质量活性(0.31 mAμgPt–1)分别是商业Pt/C的2.8倍和2.1倍.更重要的是,在加速耐久性测试中,PtP1.4@Pt/C催化剂在30000圈电位循环后质量活性仅衰减6％,在90000圈电位循环后仅衰减25％;而商业Pt/C催化剂在30000圈电位循环后就衰减46％.PtP1.4@Pt/C催化剂高活性与高稳定性主要归功于核壳结构、磷掺杂引起的电子结构效应以及磷掺杂增加了碳载体对催化剂粒子的锚定作用进而阻止了其迁移团聚.综上所述,本文为设计同时具有优异活性与稳定性非金属掺杂Pt基氧还原催化剂提供新的思路.     

ICP-AES法测定高温合金中5种非金属元素

本文研究了快速测定高温合金中5种非金属元素(As、B、P、Se、Si)的分析方法,以满足高温合金行业对非金属元素检测的需求。利用王水和高氯酸对高温合金进行酸溶解,并系统研究了基体元素和共存元素对分析元素谱线的光谱干扰情况,同时进行了分析谱线的选择。5种非金属元素的检出限在5.5 ～ 11.9 ug/ml,5次数据的相对标准偏差(RSD,n=5)为0.9 % ～ 7 %,各元素的回收率在96 % ～ 102 %之间,该方法适用于高温合金中非金属元素的测定。     

Hydrogen bonding and halogen bonding co-existing in the reaction of heptafluorobenzyl iodide with N,N,N,N-tetramethylethylene diamine

Two novel assembling systems 3 and 4, with the structures of C₆F₅CF₂⁻?H⁺N(Me)₂CH₂CH₂(Me₂)N⁺H?⁻CF₂C₆F₅ and C₆F₅CF₂I?N(Me)₂CH₂CH₂(Me)₂N?ICF₂C₆F₅, respectively, have been generated from the solution of heptafluorobenzyl iodide 1 and N,N,N^′,N^′-tetramethylethylenediamine 2 in dichloromethane. Their structures have been characterized by X-ray diffraction analysis, NMR and IR spectroscopy. Intermolecular N?I halogen bond and F?H hydrogen bond are revealed to be the driving forces for their formation.