离子液体存在下脂肪醛的环化三聚反应

Aliphatic aldehydes such as ethanal,propanal,n-butanal,isobutyraldehyde,n-valeraldehyde,isovaleraldehyde,n-hexanal and n-octanal were converted into the corresponding 2,4,6-trialkyl-1,3,5-trioxanes through cyclotrimer-ization in the presence of the ferric chloride based ionic liquids at room temperature without solvent in high selec-tivity.The effects of different ionic liquids,acidity of ionic liquids and temperature on cyclotrimerization were alsostudied.The results showed that the ferric chloride based ionic liquids(apparent molar fraction of FeCl_3(x(FeCl_3)=0.62))were a kind of efficient catalysts for the cyclotrimerization of aliphatic aldehyde which could be separatedconveniently from the reaction mixture and recycled without loss of catalytic activity.The conversion of isobu-tyraldehyde and the selectivity to 2,4,6-triisopropyl-1,3,5-trioxane were 91.1% and 99.8% respectively under opti-mum reaction condition(isobutyraldehyde 25.0 g,[Et_3NH]Cl/FeCl_3(x(FeCl_3)=0.62)1.0 g,25 ℃for 1 h).     

室温离子液体FeCl3-BPC体系的研究

利用差示扫描量热法(DSC)建立了无水三氯化铁和氯化正丁基吡啶(BPC)二元体系相图. 依据相图, FeCl₃和BPC形成室温离子液体的窗口是x＝0.26～0.58; 室温离子液体的深度是80 ℃. 利用UHF/6-31G^*对FeCl₃, FeCl₄^－, Fe₂Cl₇^－等配合物的几何结构、键长、能量和Raman频率进行优化, 从头算和Raman光谱证实了相图中FeCl₃摩尔分数x＝0.50处有稳定化合物存在, FeCl₄^－是主要阴离子; x＝0.67处, FeCl₄^－, Fe₂Cl₇^－是主要阴离子.     

Ruthenium Trichloride Catalyzed Highly Efficient Deoximation of Oximes to the Carbonyl Compounds and Nitriles without Acceptors

An acceptor‐free catalysis protocol for the deoximation of ketoximes and aldoximes using RuCl₃ as the catalyst has been developed. Under the optimized conditions, various oximes were converted to ketones and nitriles with excellent isolated yields.     

An Easy Access to Oxime Ethers by Pd‐Catalyzed C—O Cross‐Coupling of Activated Aryl Bromides with Ketoximes and Chalcone Oximes

An efficient Pd‐catalyzed method for C—O cross‐coupling of ketoximes and chalcone oximes with activated aryl bromides and bromo‐chalcones has been developed. All oxime ethers were obtained in good to excellent yields by [(π‐allyl)PdCl]₂/tBuXPhos ( L7 ) catalyst system. TrixiePhos ( L11 ) was also found to be effective for the oxime coupling. This method offers an easy and smooth coupling of chalcone oximes with activated aryl bromides and bromo‐chalcones, which has not been previously explored.     

Influence of FeCl3‐modified chloroaluminate ionic liquids on long‐chain alkenes alkylation

The influence of anhydrous ferric chloride on the catalytic properties of chloroaluminate ionic liquids catalyst for Friedel–Crafts alkylation was investigated. The catalysts were characterized by Fourier‐transform infrared (FT‐IR) (acetonitrile molecule as probe), specific gravity, and ²⁷Al NMR. Besides, the effect of the mass ratio of FeCl₃ to AlCl₃, catalysts dosage, toluene/olefin molar ratio, reaction temperature, and reaction time on long‐chain alkenes alkylation were investigated thoroughly. And bromine value and high‐performance liquid chromatography (HPLC) were employed as the evaluation method for alkylation products. It was observed that the addition of anhydrous ferric chloride results in improvement in terms of Lewis acid and its catalytic recyclability. Among these catalysts studied, the catalyst modified with 1.0 wt.% anhydrous FeCl₃ showed the best catalytic performance in terms of yield and stability, which can be attributed to the formation of new stronger acidic ions [Al₂FeCl_l0]^? when the added ferric chloride reacts with acidic ions [Al₂Cl₇]^?.     

A Convenient Method for the Preparation of 1,5‐Diaryl‐3‐(arylamino)‐1H‐pyrrol‐2(5H)‐ones

A simple and eco‐friendly method for the preparation of 1,5‐diaryl‐3‐(arylamino)‐1H‐pyrrol‐2(5H)‐ones via the cyclo‐condensation reaction of aldehydes, amines and ethyl pyruvate in the presence of silica supported ferric chloride (SiO₂‐FeCl₃) as reusable heterogeneous catalyst is described. The present methodology offers several advantages such as excellent yields, simple procedure and short reaction times.     

The synthesis of Fe-containing ionic liquid and its catalytic performance for the dehydration of fructose

Four Fe-containing ionic liquids (ILs) were synthesized by coupling of conventional imidazole ionic liquids [C_xmim]Cl (x = 4, 8, 12, 16) with FeCl₃ and were characterized by FT-IR, Raman, ESI–MS and TG. All of the Fe-containing ILs were applied to the conversion of fructose into 5-hydroxymethylfurfural (HMF) in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) subsequently and the result showed that [C₁₆mim]FeCl₄ exhibited excellent catalytic performance. Then the different reaction parameters with [C₁₆mim]FeCl₄ as catalyst were studied in detail. A 92.8% yield of HMF was obtained with 0.03 g [C₁₆mim]FeCl₄ and 0.1 g fructose in 1.0050 g [Bmim]Cl at 80 °C for 40 min in fructose/[Bmim]Cl solution.     

Magtrieve™ (CrO2) and MnO2 mediated oxidation of aldoximes: studying the reaction course

Magtrieve™ (CrO₂) and MnO₂ mediated oxidation of aldoximes to nitrile oxides were studied in details. In presence of external radical source, TEMPO, these reagents did not furnish nitrile oxides, instead favoured deoximation to aldehydes. A common trend of deoximation was established from electronically tuned aldoximes, which is: aliphatic>aromatic>aldoximes with strong electron-withdrawing group, though the extent of deoximation was less in case of CrO₂. Above effects were not observed with chloramine-T and diacetoxyiodobenzene, reagents known to produce nitrile oxides via hydroximoyl halide or equivalent ionic intermediates. A putative reaction mechanism is proposed for MO₂ (M=Cr, Mn) mediated oxidation of aldoximes through formation of a nitroso-oxime tautomeric pair. Formation of nitrile oxide is possibly occurred from the oxime tautomer via a σ-type iminoxy radical intermediate. The deoximation process, dominating in presence of external radical environment, is explained following decomposition of the nitroso tautomer.     

Eco‐friendly and Efficient Synthesis of 2,3‐Dihydroquinazolin‐4(1H)‐ones

A simple and facile method for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones through the direct cyclocondensation of one‐pot three‐component cyclocondensation of isatoic anhydride, ammonium acetate (or primary amines) and aldehydes; and anthranilamide and aldehydes using silica supported ferric chloride (SiO₂‐FeCl₃) as catalyst under solvent‐free conditions is described.     

Biomimetic Interaction between FeII and O2: Effect of the Second Coordination Sphere on O2 Binding to FeII Complexes: Evidence of Coordination at the Metal Centre by a Dissociative Mechanism in the Formation of μ‐Oxo Diferric Complexes

We report that the formation of μ‐oxo diferric compounds from O₂ and FeCl₂ complexes within the tris(2‐pyridylmethyl)amine series (N. K. Thallaj et al. Chem. Eur. J., 2008 , 14, 6742–6753) involves coordination of O₂ to the metal centre and that this reaction occurs following initial dissociation of the bound equatorial chloride anion. We also report evidence of the formation of a reduced form of dioxygen by an inner‐sphere mechanism, thus leading to modification of the ligand. The solid‐state structures of [FeCl₂L] complexes (L¹=mono(α‐pivalamidopyridylmethyl)bis(2‐pyridylmethyl)amine, L²=mono(α‐pivalesteropyridylmethyl)bis(2‐pyridylmethyl)amine, L³=bis(α‐pivalamidopyridylmethyl)mono(2‐pyridylmethyl)amine are described, and spectroscopic data support the structural retention in solution. In [FeCl₂L³], the two amide hydrogen atoms stabilise the equatorial chloride anion in such a way that its exchange by a weak ligand is impossible: [FeCl₂L³] is perfectly oxygen‐stable. In [FeCl₂L²], the equatorial chloride anion is completely free to move and coordination of O₂ can take place. The reaction product with [FeCl₂L²] is a μ‐oxo diferric complex in which the ester function has been transformed into a phenol group. This conversion can be seen as a hydrolysis reaction in basic medium, hence supporting the initial formation of a reduced form of dioxygen in the medium. Complex [FeCl₂L¹] exhibits a very weak reactivity with O₂, in line with a semistabilised equatorial chloride counteranion.     

Basic ionic liquid/FeCl3·6H2O as an efficient catalyst for AGET ATRP of methyl methacrylate

A basic ionic liquid, 1‐butyl‐3‐methyl imidazolium hydroxide ([Bmim]OH), was synthesized and used as the additives in an iron‐mediated atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) of methyl methacrylate in bulk and solution, using FeCl₃ · 6H₂O as the catalyst, ethyl 2‐bromoisobutyrate as the initiator, vitamin C (Vc) as the reducing agent, and tetrabutylammonium bromide or tetra‐n‐butylphosphonium bromide as the ligand. Catalytic amount of [Bmim]OH could enhance the polymerization rate and produce poly(methyl methacrylate) with controllable molecular weights and narrow molecular weight distributions (M_w/M_n = 1.3–1.4). The nature of controlled/“living” free radical polymerization in the presence of basic ionic liquid was further confirmed by chain‐extension experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of alkyl nitrones by reaction of aldehyde and ketone oximes with α,β-unstaturated esters in the presence of Lewis acid

Reactions of pyridinecarbaldehyde oximes, methyl pyridyl ketone oximes, furfural oxime, cinnamaldehyde oxime, and crotonaldehyde oxime with acrylic and methacrylic acid esters in the presence of a Lewis acid catalyst at room temperature followed the conjugate addition pattern to give the corresponding alkyl nitrones in good yield. The best yields were obtained using a 1: 1 mixture of CdI₂ and BF₃ · Bu₂O as catalyst. Published in Russian in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 4, pp. 605–609. The text was submitted by the authors in English.     

Chloride‐Induced Highly Active Au Catalyst for Methyl Esterification of Alcohols

Chloride is generally regarded as a harmful species for the heterogeneous catalysts, especially Au catalysts. In this work, a series of active Au/NiO_x catalysts were successfully prepared with co‐precipitation method by tracking the concentrations of chloride in the re‐dispersed aqueous solutions. For methyl esterification of alcohols, the highest active Au/NiO_x catalysts could be prepared from aqueous solutions containing 8‐13 ppm chloride, the yield of methyl benzoate of catalyst Au/NiO_x‐9 was 99%. The catalyst structures and the role of chloride in catalysts were explored by ICP, BET, XPS, TEM and EXAFS characterizations. It was found that the appropriate amount of residual chloride in Au catalysts was beneficial to their catalytic activities. Especially for Au/NiO_x‐9, the appropriate amount of residual chloride had positive effects on the physicochemical properties of Au/NiO_x catalyst, the position of Au nanoparticles (NPs) located on NiO_x crystallites and the ratio of Au^δ+/Au⁰ in catalyst, which together resulted in its high reactivity.     

Novel catalyst system of MCl2/FeCl3·6H2O/PPh3 (M = Ni,Co, or Mn) for the atom transfer radical polymerization of methyl methacrylate

MCl₂ (M = Ni, Co, Sn, or Mn) and PPh₃ together acted as a catalyst for the radical polymerization of methyl methacrylate (MMA) in the presence of ethyl 2‐bromoisobutyrate as an initiator. The four systems all led to conventional radical polymerizations, which yielded polymers with a weight‐average molecular weight/number‐average molecular weight (M_w/M_n) ratio greater than 2.0 and became well controlled when a certain amount of FeCl₃·6H₂O was added. The polymerizations of MMA catalyzed by these four FeCl₃‐modified catalyst systems provided well‐defined polymers with low polydispersities (M_w/M_n < 1.28). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2625–2631, 2005     

Hydrolysis of carboxylate and phosphate esters using monopyridinium oximes in cationic micellar media

The reactions of p‐nitrophenyl acetate (PNPA) with a series of monopyridinium oximes, viz. 2‐PAM (2‐hydroxyiminomethyl‐1‐methylpyridinium iodide), 3‐PAM (3‐hydroxyiminomethyl‐1‐methylpyridinium iodide), and 4‐PAM (4‐hydroxyiminomethyl‐1‐methylpyridinium iodide) have been studied in the presence of cationic surfactants of same hydrophobic chain length (C₁₆) within the concentration range of 0.5–6.0 mM at pH 8.0 under the pseudo‐first‐order condition. The observed rate constant (k_obs) increases with increasing surfactant concentration culminating into a maximum, and this has been analyzed in detail following the concepts of micellar catalysis. The structure–activity relationship of the investigated oximes has been discussed, and 2‐PAM was found to be the most reactive among all the three investigated oximes for the cleavage of PNPA. Esterolytic decomposition of p‐nitrophenyldiphenyl phosphate with oximate ions (? CH?NO^?) was followed in cetyltrimethylammonium bromide micelles at pH 9.0, and 4‐PAM was the most reactive oxime for the micellar hydrolysis of phosphate ester. The apparent acid dissociation constants (pK_a) of the investigated oximes have been determined spectrophotometrically. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 569–578, 2011     

Amino acid ionic liquid‐based titanomagnetite nanoparticles: An efficient and green nanocatalyst for the synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazoles

The amino acid ionic liquid tetrabutylammonium asparaginate (TBAAsp) was immobilized on titanomagnetite (Fe_3?xTi_xO₄) nanoparticles in a facile one‐pot process using an organosilane compound (TMSP) as spacer. The modified Fe_3?xTi_xO₄@TMSP@TBAAsp magnetic nanoparticles were characterized using Fourier transform spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, vibrating sample magnetometry and thermogravimetric analysis. The resulting analytical data clearly verified the successful immobilization of the ionic liquid on the magnetic substrate. The magnetic ionic liquid‐based nanoparticles exhibited high catalytic activity in the synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazole derivatives via a one‐pot three‐component reaction under mild reaction conditions. The catalyst was easily recycled and reused for at least six runs without any considerable loss of activity.     

A Facile Beckmann Rearrangement of Oximes with AlCl3 in the Solid State

Abstract

A facile and efficient synthetic procedure, for Beckmann rearrangement of oximes with AlCl₃ in the absence of solvent is developed. We have been able to convert cyclohexanone oxime to ?-caprolactam in a quantitative yield.     

Polarographisches Verhalten von 1,2,3-Cyclohexantrion-trioxim in sauren Lösungen

The deoximation kinetics of 1,2,3-cyclohexanetrione trioxime was studied polarographically in 0.5 and 1.0M-HClO₄ solutions. From the three vicinal oxime groups, that in position 2 is hydrolysed by protonisation, followed by water uptake and hydroxylamine loss. The probable mechanism of the deoximation was proved by the study of the polarographic behaviour of 1,2,3-cyclohexanetrione-1,3-dioxime and by means of amperometric determination of the unchanged trioxime with Ni(II)-salt.     

Different hydrogen‐bonding modes in two closely related oximes

Two closely related oximes, namely 1‐chloroacetyl‐3‐ethyl‐2,6‐diphenylpiperidin‐4‐one oxime, C₂₁H₂₃ClN₂O₂, (I), and 1‐chloroacetyl‐2,6‐diphenyl‐3‐(propan‐2‐yl)piperidin‐4‐one oxime, C₂₂H₂₅ClN₂O₂, (II), despite their identical sets of hydrogen‐bond donors and acceptors, display basically different hydrogen‐bonding patterns in their crystal structures. While the molecules of (I) are organized into typical centrosymmetric dimers, created by oxime–oxime O—H...N hydrogen bonds, in the structure of (II) there are infinite chains of molecules connected by O—H...O hydrogen bonds, in which the carbonyl O atom from the chloroacetyl group acts as the hydrogen‐bond acceptor. Despite the differences in the hydrogen‐bond schemes, the –OH groups are always in typical anti positions (C—N—O—H torsion angles of ca 180°). The oxime group in (I) is disordered, with the hydroxy groups occupying two distinct positions and C—C—N—O torsion angles of approximately 0 and 180° for the two alternatives. This disorder, even though the site‐occupancy factor of the less occupied position is as low as ca 0.06, is also observed at lower temperatures, which seems to favour the statistical and not the dynamic nature of this phenomenon.     

Iron‐mediated AGET ATRP of methyl methacrylate using metal wire as reducing agent

Methyl methacrylate (MMA) were successfully polymerized by atom transfer radical polymerization with activator generated by electron transfer (AGET ATRP) using copper or iron wire as the reducing agent at 90°C. Well‐controlled polymerizations were demonstrated using an oxidatively stable iron(III) chloride hexahydrate (FeCl₃·6H₂O) as the catalyst, ethyl 2‐bromoisobutyrate (EBiB) as the initiator, and tetrabutylammonium bromide (TBABr) or triphenylphosphine as the ligand. The polymerization rate was fast and affected by the amount of catalyst and type of reducing agents. For example, the polymerization rate of bulk AGET ATRP with a molar ratio of [MMA]₀/[EBiB]₀/[FeCl₃·6H₂O]₀/[TBABr]₀ = 500/1/0.5/1 using iron wire (the conversion reaches up to 82.2% after 80 min) as the reducing agent was faster than that using copper wire (the conversion reaches up to 86.1% after 3 h). At the same time, the experimental M_n values of the obtained poly(methyl methacrylate) were consistent with the corresponding theoretical ones, and the M_w/M_n values were narrow (～1.3), showing the typical features of “living”/controlled radical polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012