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lidanf_1木虫 (小有名气)
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乙醇铁的合成方法
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wjiawei
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lidanf_1(金币+3,VIP+0): 9-29 10:27
lidanf_1(金币+3,VIP+0): 9-29 10:27
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2.2.1.1乙醇铁的制备 采用氨法制备乙醇铁，反应式如下： 3C2H5OH+FeCl3+NH3====Fe(OC2H5)3+3NH4Cl 制备过程在绝对无水的条件下进行，所用溶剂及反应物需绝对无水，试剂的除水 处理是必需的，仪器连接采用标准接口。 乙醇的除水：取1000ml园底烧瓶安装回流冷凝管，在冷凝管上端附加一只氯化 钙干燥管，瓶内放置2－3g干燥洁净的镁条与0.3g碘，加入30ml 99.5%的乙醇，在 水浴内加热至碘粒完全消失(如果不起反应可加入数小粒碘)，然后继续加热，待镁 完全溶解后，将500ml 99.5的乙醇加入，继续加热回流1小时，蒸出乙醇，先蒸出 的10ml弃去，收集于干燥洁净的瓶内储存，如此所得的乙醇纯度可超过99.95%。 催化剂也可用CCl4代替碘。 苯的纯化：往苯中加入洁净小钠粒，放置若干时间后，蒸出苯，可得无水苯。 无水FeCl3 30g溶于300g苯与120g乙醇混合液中（1000ml烧瓶中），通入过量 NH3进行反应。反应放热，NH3一直通入，直到反应物温度冷至室温。反应完毕， 剩余NH3和溶剂在减压下蒸干。剩余物用300ml苯萃取，滤去不溶物NH4Cl。减压 下蒸干滤出液得一棕色粘稠物，溶于60ml乙醇。深褐色的乙醇铁针状晶体（8.4g） 缓慢沉淀下来。 |
2楼2009-09-29 10:11:21
wjiawei
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3楼2009-09-29 10:12:26
vjyong
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lidanf_1(金币+3,VIP+0): 9-29 10:28
lidanf_1(金币+3,VIP+0): 9-29 10:28
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The synthesis of iron (III) ethoxide revisited: Characterization of the metathesis products of iron (III) halides and sodium ethoxide The synthesis of iron (III) ethoxide revisited: Characterization of the metathesis products of iron (III) halides and sodium ethoxide Gulaim A. Seisenbaevaa, Suresh Gohila, Evgeniya V. Suslovab, Tatiana V. Rogovab, Nataliya Ya. Turovab and Vadim G. Kesslera, Corresponding Author Contact Information, E-mail The Corresponding Author aDepartment of Chemistry, SLU, Box 7015, SE-75007 Uppsala, Sweden bDepartment of Chemistry, Moscow State University, 119899 Moscow, Russia Received 6 September 2004; revised 14 February 2005; accepted 6 March 2005. Available online 27 June 2005. Abstract Interaction of FeX3, X = Cl, Br with 3 equiv. of NaOEt in toluene/ethanol media provides mixtures of iron (III) oxoethoxide, Fe5O(OEt)13, and its halide alkoxide analogs. The latter have been identified by mass-spectrometric study as Fe5O(OEt)12X and Fe5O(OEt)11X2. Application of FeBr3 as a starting material leads to much more pure samples of Fe5O(OEt)13 isolated with higher yields. Graphical abstract Interaction of FeX3, X = Cl, Br with 3 equiv. of NaOEt in toluene/ethanol media provides mixtures of iron (III) oxoethoxide, Fe5O(OEt)13, and its halide alkoxide analogs. Full-size image Full-size image (12K) Keywords: Iron oxo-ethoxide; Mass-spectrometry; X-ray study; Sol–gel Article Outline 1. Experimental 1.1. Typical synthetic procedure 1.2. Crystallography 2. Results and discussion Appendix A. Supplementary data References The alkoxides of iron find increasing application in a broad area covering such topics as homogeneous catalysis, especially the lactide polymerization [1] and [2], and the synthesis of inorganic materials with the focus on preparation of magnetic nanoparticles and magnetic coatings of iron oxides [3], [4], [5] and [6]. The oldest representative of this family, iron (III) ethoxide [7] and [8], is even commercially available (from STREM Ref. 26-2550 or Johnson Matthey, Ref. 41863). The nature of this product, delivered commercially as a brown powder, remained, until recently, rather unclear. The researchers who used it noticed that it contained considerable amounts of chloride impurities [1] and [9]. It has been noted also that the samples of this product displayed also varying and not really reproducible physical chemical characteristics such as melting points (105–120 °C) and solubility in parent alcohol. The analysis of the brown crystals, obtained by recrystallization from ethanol of the products of iron (III) chloride and sodium ethoxide metathesis reaction, showed them to be noticeably deficient on carbon and hydrogen [10]. The unit cell parameters for those crystals were very close to the parameters observed for the aluminum oxoethoxide, Al10O4(OEt)22 [11], which permitted the authors of [10] to suppose the analogy in composition and structure of these compounds. An attempt to separate the mixture of products delivered commercially as iron (III) ethoxide was reported recently by O’Keefe et al., who have carried out an extraction with tetrahydrofurane with subsequent evaporation and recrystallization from hexamethyldisiloxane, resulting in isolation of yellow crystals of Fe5O(OEt)13 with unit cell parameters (measured at 153 K) substantially different from those observed for the brown crystals in [10]. It should be mentioned that the true oxo-ligand free iron (III) ethoxide – a completely insoluble bright yellow powder with a structure related to the type of Al(OH)3 gibbsite – has been isolated by Turova and coworkers [12] and [13] on reaction of the oxoethoxide with titanium or niobium ethoxides: [FeOx(OEt)3-2x]n+Ti(OEt)4right harpoon over leftFe(OEt)3↓+TiOx(OEt)4-2x The equilibrium in this reaction was shifted in favor of formation of the homoleptic iron (III) ethoxide apparently due to its poor solubility. Precipitation of insoluble Fe(OEt)3 was observed also from the freshly prepared solutions of Fe(OiPr)3 in ethanol [14]. Veith et al. have reported recently an X-ray single crystal study of a more oxo-ligand substituted iron ethoxide, Fe9O3(OEt)21(EtOH), obtained by stirring a mixture of FeCl3 with NaOEt in EtOH on reflux for 100 h (!) with subsequent distillation at 200 °C/0.01 mm Hg and recrystallization from ethanol [15]. It is difficult to judge what extent the crystal studied was representative for the composition of the obtained product, as no convincing confirmation of its identity with the bulk has been provided, but the applied hard thermal treatment was resulting supposedly in partial destruction leading to increase in the oxo-ligand substitution in the product. In the present publication, we report the separation of the product mixture obtained according to Bradley et al. [7] by metathesis of iron halides with sodium ethoxide in hydrocarbon/ethanol media, characterization of the major reaction product as Fe5O(OEt)13 (1) and mass-spectrometric identification of the byproducts as halide substituted oxo-alkoxides. 1. Experimental All manipulations were carried out in a dry nitrogen atmosphere using Schlenk technique or a glove box. Anhydrous FeCl3 and FeBr3 were purchased from Aldrich and used without further purification. Ethanol was dried by refluxing over Ca(OEt)2 with subsequent distillation and toluene – by distillation over lithium-aluminum hydride. Mass-spectra were recorded using JEOL JMS-SX/SX-102A mass-spectrometer applying electron beam ionization (U = 70 eV) with direct probe introduction. IR spectra of pellets pressed with dry KBr were registered with a Perkin–Elmer FT-IR spectrometer 1720 X. The results of microanalysis were obtained by Mikro Kemi AB, Uppsala, Sweden, using the combustion technique (C, H) and by complexometric titration (Fe). The content of halides (Cl, Br) was determined using Vollgard titration (reverse titration with NaSCN of a weighted sample dissolved in 2 M HNO3 after precipitation of halides with an aliquot of AgNO3, the auto-indication been provided by the presence of Fe(III)-cations). 1.1. Typical synthetic procedure Sodium metal (not, vert, similar1 g, 40–50 mmol) was dissolved on reflux in a mixture of 5–6 ml EtOH and 25 ml toluene. An equivalent amount of dry FeX3 was added to the warm solution and the mixture was subjected to reflux for two more hours. It was then left for precipitation of NaX overnight. The solution was removed by syringe and the sediment extracted twice with 20 ml portions of toluene on reflux. The solution fractions were joined and evaporated to dryness in vacuo, leaving an orange-brown waxy solid. The solid was dissolved in 3–4 ml of hexane and left for crystallization overnight at −30 °C, leaving uniform crystals formed as transparent orange rhombs. The remaining solution was removed by a syringe and the solid dried in vacuo. Yields were reproducibly about 2 g starting from chloride (corresponding to 70–75%) and 2.3–2.5 g starting from bromide (80–90%). Found: C, 35.8; H, 7.4; Fe, 31.3%. For the chloride route, Cl about 0.1%, bromide route, Br – traces (very light opalescence with silver nitrate). Anal. Calc. for Fe5O(OEt)13 (1): C, 35.4; H, 7.3; Fe, 31.8%. M.P. 120 ± 0.5 °C. IR, cm−1, 2970 m, 2930 m 2870 m, 1475 m, 1445 m, 1380 m, 1360 w, 1155 s br, 1105 s, 1065 s br, 920 m, 900 s, 840 m, 685 m, 550–570 s, 475 m br. MS, m/z (I,%), interpretation: 853(*), Fe5O(OEt)12(OH)+, 836(*), View the MathML source, 825(*), View the MathML source, 808(*), View the MathML source, 791(90.9), View the MathML source, 746(2.1), View the MathML source, 701(2.0), View the MathML source, 645(100), View the MathML source and View the MathML source, 600(12.4), View the MathML source, 555(6.1), View the MathML source, 528(10.4), View the MathML source and View the MathML source, 510(4.10), View the MathML source, 483(5.4), View the MathML source, 465(14.1), View the MathML source, 454(24.4), View the MathML source, 444(11.0), View the MathML source, 421(33.5), Fe4(OEt)4(OH)+, 376(24.7), Fe4(OEt)3(OH)+, 375(23.8), View the MathML source, 364(8.3), View the MathML source, 337(4.6), View the MathML source, 291(12.3), Fe3O(OEt)2(OH)+, 274(43.1), View the MathML source, 247(46.9), View the MathML source, View the MathML source, 202(15.8), View the MathML source, 201(18.5), Fe3O(OH)+, 191(7.4), View the MathML source, 173(10.3), Fe2O(OEt)+, 146(11.2), View the MathML source, 145(36.01), Fe2O(OH)+, 135(17.1), View the MathML source, 131(22.6), Fe(OEt)(OCH2)+, 21(11.9), Fe(OH)2(OCH3)+, 117(24.3), FeO(OEt)+, 101(74.4), Fe(OEt)+. The asterisk denotes ions registered outside the calibration interval of masses (m/z = 16–800). The crystals obtained from chloride display always an additional peak at m/z = 781 with varying intensity; the crystals obtained from bromide are almost free from additional peaks. The solution fractions were evaporated in vacuo providing waxy solids that were also analyzed. The carbon, hydrogen and iron contents in them did not deviate noticeably from the average in the crystals, while the halide content was considerably higher (1.5–2.0% Cl and 0.2–0.4% Br, respectively). The IR spectra were completely identical to those of Fe5O(OEt)13, while in the mass-spectra observed additional series of ions were observed. Additional ions in the MS of chloride-derived product, m/z for 35Cl (I,%), interpretation: 781(100), Fe5O(OEt)10Cl+, 771(19.2), View the MathML source, 736(2.4), Fe5O(OEt)9Cl+, 691(2.3), Fe5O(OEt)8Cl+, 664(5.8), Fe4(OEt)9Cl+, 654(2.8), View the MathML source, 646(41.2), Fe5O(OEt)7Cl+, 635(17.8), Fe4O(OEt)8Cl+, 619(1.8), Fe4(OEt)8Cl+, 590(3.4), Fe4O(OEt)7Cl+, 518(16.1), Fe3(OEt)7Cl+, 473(22.8), Fe3(OEt)6Cl+, 463(13.9), View the MathML source. Additional ions in the MS of bromide-derived product (calibration interval m/z = 500–1000), m/z for 81Br (I,%), interpretation: 908(0.4), View the MathML source, 872(1.6), Fe5O(OEt)11Br+, 710(0.9), Fe4(OEt)9Br+, 564(2.4), Fe3(OEt)7Br+, 519(2.3), Fe3(OEt)6Br+. 1.2. Crystallography The X-ray single crystal study of the crystals of 1 was carried out with a Bruker SMART CCD 1k diffractometer with Mo Kα-radiation, λ = 0.71073 Å at 22 °C. Crystal data for C26H65Fe5O14: Triclinic, View the MathML source, a = 12.022(7), b = 12.346(6), c = 16.348(9) Å, α = 100.121(17), β = 100.998(12), γ = 112.815(13)°, V = 2110(2) Å3, z = 2, d = 1.387 g/cm3. 2876 independent reflections [Rint = 0.0412] were collected to 2θ less-than-or-equals, slant 36.00° because of rather poor reflectivity at higher angles. The structure was solved by standard direct methods. Coordinates of the metal atoms were obtained from the initial solution and those of other non-hydrogen atoms were located in subsequent difference Fourier syntheses. Both metal and oxygen atom positions were refined against F2 first in isotropic and then in anisotropic approximations, while the carbon atoms – only in isotropic approximation in the view of thermal disorder and limited volume of available data. The coordinates of hydrogen atoms were calculated geometrically and included into the final cycles of refinement in isotropic approximation. Final discrepancy factors were R1 = 0.0665, wR2 = 0.1707 for 1735 observed reflections (I > 2σ(I)). All calculations have been carried out using the shelxtl-nt program package on a personal computer [16]. The identity of the single crystal studied to the bulk of the sample was confirmed both by determination of unit cell parameters for a number of randomly chosen single crystals and also by successful indexing of the powder pattern for the sample of 1 using the unit cell parameters determined for the single crystal. Most intensive line in the X-ray powder pattern of 1 (DRON-2 diffractometer, Co Kα-radiation, λ = 1.54056 Å  , in the format d, Å (I, %), indexing: 11.04(37), 0 1 0, 10.70(60), 1 0 0, 10.27(63), 0 −1 1, 10.17(100), −1 1 0, 7.91(18), 0 1 1, 7.70(31), 0 0 2, 6.13(14), −1 1 2.2. Results and discussion In the view of importance of “soluble iron ethoxide” prepared by metathesis of iron halides with sodium ethoxide for a variety of different applications in modern industries, it appeared very attractive to try to identify the species present in this product and explain the irreproducibility of physical chemical characteristics often observed for the samples of this product. It is important to note that the phenomenon of coordination polymerism, i.e., the co-existence of the chemically identical but structurally different molecular forms, is theoretically impossible for the derivatives of iron (III) because of their extreme kinetic lability. The variations in the melting points and solubility could only be caused by the presence of the chemically different impurities. The mass-spectral analysis reported in the present work (see Fig. 1(a)–(c)) demonstrated clearly that the reaction product is in this case contaminated with halide impurities, which in the chloride-derived system cannot be removed completely even by repeated re-crystallizations: View the MathML source Full-size image (75K) - Opens new window Full-size image (75K) Fig. 1. Principal fragmentation schemes for the pentanuclear species present in the samples of “soluble iron ethoxide”: pure Fe5O(OEt)13 (a), chloride impurities (b), bromide impurities (c). View Within Article These are supposedly these impurities that can lead to variation in the physical chemical properties for the samples of “soluble iron ethoxide”. The major component in this mixture has been established to be pentanuclear iron oxo-ethoxide, Fe5O(OEt)13 (1). Formation of the oxo-species is in this case due to elimination of alkyl halides from the initially formed alkoxo-halide species. The formation of alkyl halides EtX, X = Cl, Br has been confirmed by a GC–MS investigation. The experimental mass distribution profiles for the heaviest halide-containing ions in the fragmentation patterns of the samples, Fe5O(OEt)10Cl+ (Fig. 2(a)) and Fe5O(OEt)10Br+ (Fig. 3(a)), have been found to correspond exactly to those calculated on the basis of the natural isotope distribution (Fig. 2 and Fig. 3(b), respectively), confirming the correctness of identification of the impurities. There is no overlap in the tops corresponding to the heaviest ions in each of the series in the spectrum of the sample enriched with chloride impurities (see Fig. 4), i.e., alkoxide-only, View the MathML source, monochlorosubstituted, Fe5O(OEt)10Cl+, and dichlorosubstituted, View the MathML source, which permitted an unambiguous identification of the fragmentation pathways demonstrated in Fig. 1(a)–(c). |
4楼2009-09-29 10:15:26
