Tetraethyl suspension

To a suspension of UDP (4.5 mmol) in toluene (10 ml) in a laboratory ultrasonic cleaning bath under N2 was added a solution of 2,2,5,5-tetraethyl-3-sulfolene (1.5mmol) in toluene (10ml). The sonication was continued for 30 min, during which time a bright-blue colour developed. A solution of t-BuOH in THF (0.45 mol dm"3,4.4 mmol) was added dropwise over a period of 30 min, whereupon the potassium was completely consumed. The mixture was filtered through a short silica gel column to remove the solid precipitate, and the filtrate was concentrated under reduced pressure. Purification by HPLC (Lichrosorb column, hexane) yielded the corresponding diene in a 92% yield. 

Four precipitated iron-based catalysts were used. The first catalyst consisted of only iron. The other catalysts contained either added potassium, added silicon or both. The catalysts were designated in terms of the atomic ratios as lOOFe, 100Fe/3.6Si, 100Fe/0.71K and 100Fe/3.6Si/0.71K. The catalysts were prepared by continuous precipitation from iron (111) nitrate and concentrated ammonium hydroxide. For silica-containing catalysts, a colloidal suspension of tetraethyl ortho silicate was mixed with the iron nitrate solution prior to precipitation. Potassium was added to the catalysts in the form of potassium tertiary butoxide during the loading of the FTS reactor. 

Silica supports were prepared by a complexing-agent assisted sol-gel method from tetraethyl orthosilicate and calcined at 500°C for 2h. Titanium iso-propoxide was added to silica-2-propanol suspension and then water was added to the suspension. The resulting solid was dried at 110 C and then calcined at 500°C for 2h. 

Al metal powder was oxidized in tetrapropyl ammonium hydroxide 40 wt.% aq. (TPAOH) in a polypropylene bottle under gentle stirring allowing the Hj to escape. After complete dissolution, tetraethyl orthosilicate (TEOS) was added to the tetrapropylammonium aluminate solution under vigorous stirring. After TEOS was completely hydrolyzed, water was added and stirring continued for another 24 h at room temperature. The final molar composition of the resulting clear solution was (TEOS)2s(TPAOH)9(H20)4oo(Al)o,5. Clear solutions are suspensions of MFI zeolite precursor units called nanoslabs [9,10]. 

Tetraethyl dimethylaminomethylenediphosphonate in anhydrous dioxane added dropwise to a suspension of NaH in the same medium, benzaldehyde added at room temp, after the initial reaction has subsided, and warmed 1 hr. at 60 -> diethyl (l-dimethylaminostyryl)phosphonate (Y 66,5%) boiled briefly with coned. HCl phenylacetic acid (Y 1A%). Overall Y AA%. F. e. s. H. Gross and B. Costi-sella, Ang. Ch. 80, 364 (1968). 

Rheological experiments were used by Wittmar et al. (2012) for the stability analysis of functionalised nanoparticles in ionic liquid. The authors examined viscosity curves (i.e. viscosity vs. shear rate) as well as viscoelastic properties for suspensions of varying particle concentration but identical preparation history. The qualitative criterion for destabilisation was whether the suspensions did gel, i.e. whether the storage modulus G was smaller the loss modulus G". A different approach was proposed by Vogelsberger et al. (2000), who studied the nucleation and aggregation kinetics of silica, synthesised via TEOS (tetraethyl-orthosilicate) condensation and precipitation. For that purpose, the viscosity and the viscoelastic moduli were continuously monitored. The latter data were i. a. used to derive the rate of aggregation. 

Sol-gel growth techniques. The most common example is the production of synthetic opal. The first step consists to produce a suspension of monodisperse silica nanospheres in ethanol obtained by the direct hydrolysis of tetraethyl ester of orthosilicic acid, SifOC H l with ethanol using ammonia as a catalyst according to the following reaction ... 

Na added at -60° under argon to a stirred suspension of 2,5-dimethylthiothio-phene-3,4-dialdehyde tetraethyl acetal in liq. NHg-ether product. Y 88%. Y. L. Gol dfarb and M. A. Kalik, Khim. Geterotsikl. Soedin. 1970, 1323 C. A. 74, 76240. 

Mesoporous SBA-15 was prepared starting from tetraethyl orthosilicate (TEOS, Aldrich 98%), as silica source and using a triblock poly (ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (E020P070E020, Pluronic P123, Aldrich), as template, according to published procedure [3]. In a typical preparation, 8.1 g Pluronic P123 was dissolved in 146.8 g de-ionized water and 4.4 g of cone. HCl (37%) and stirred over night at 35°C in a 250 ml one neck flask. To this solution 16 g of TEOS was quickly added and stirred for 24 h at 35°C. The milky suspension was aimealed at 100°C for 24 h in closed polypropylene bottle. The solid product was filtered, washed with an HCl/water-mixmre and calcined at 550°C for 5h in air. 

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