Aqueous solution isopropoxides

A mixture of 37.6 g of N-acetyl-L-glutamine and 1.000 ml of water is heated to 40°C, and 900 ml of an isopropanol solution containing 40 g of aluminum isopropoxide isadded to the warm mixture with stirring. The stirring is continued for 10 minutes. The reaction mixture is filtered and the filtrate is concentrated under reduced pressure. Isopropanol is added to the aqueous solution and the salt precipitates in the solution. The precipitates are collected by filtration and upon drying, 48.5 g of the crystalline-like aluminum salt of N-acetyl-L-glutamine are obtained. 

Immobilizing DENs within a sol-gel matrix is another potential method for preparing new supported catalysts. PAMAM and PPI dendrimers can be added to sol-gel preparations of silicas " and zinc arsenates to template mesopores. In one early report, the dendrimer bound Cu + ions were added to sol-gel silica and calcined to yield supported copper oxide nanoparticles. Sol-gel chemistry can also be used to prepare titania supported Pd, Au, and Pd-Au nanoparticle catalysts. Aqueous solutions of Pd and Au DENs were added to titanium isopropoxide to coprecipitate the DENs with Ti02. Activation at 500°C resulted in particles approximately 4 nm in diameter. In this preparation, the PAMAM dendrimers served two roles, templating both nanoparticles and the pores of the titania support. 

Titanium(IV) isopropoxide (Ti(OCH(CH3)2)4) and isopropanol were purchased from Aldrich and used without any further purification. Ammonia water(28%), methyl mercaptan standard solution(lpg/mL in benzene solution, Wako) and acetaldehyde aqueous solution(3%) were applied as odors. All of these chemicals were used without further purification. 

If the silica is treated with fluoride prior to titanation, which converts many of the silanol groups into Si-F surface groups, the reaction with titanium alkoxide is inhibited and the treatment is less effective. The data in Table 34 illustrate this outcome. Silica samples were treated (or not) with two fluoride compounds in aqueous solution, then they were dried at 260 °C in the normal way prior to titanation. Titanium isopropoxide was added to make the catalyst contain 5 wt% Ti. Each sample was then calcined at 815 °C in air. Chromium was applied (0.5 wt%) as bis(f-butyl) chromate) in hexane solution (two-step activation, see Section 12). After final activation in air at 315 °C, each sample was tested at 102 °C, and the polymer MI values obtained are listed in the table. The change in MI shows that the titanium did not attach well to the carrier in the presence of fluoride. As more fluoride was added, the polymer MI dropped. 

Method (b) was reported by Wang et al. They used titanium isopropoxide cyclohexane solution (oil phase) and aqueous solution of alkali (water phase) as raw material solutions. These two solutions flowed from different inlets and were made to meet in a microreactor to react at the interface between these solutions. Here, the microreactor was mainly used to obtain a stable interface for nanoparticle generation. It was reported that a thin mixed phase ( 1 nm) existed in the oil-water interface where the reaction mainly occurred. In this case, they utilized easily... 

Titanium(IV) isopropoxide, an aqueous solution of sodium hydroxide, a solution of 25 weight % tetramethylammonium hydroxide in methanol, aluminum nitrate nonahydrate and tetrapropylammonium bromide were used in the preparation of sodium CT. These chemicals were mixed to produce a white slurry. The slurry was loaded into a closed reactor and heated in an oven set at a temperature in the range of 423-473 K. The crystallization time was varied between twelve hours to two days. The synthesis details were presented by Anthony and Dosch [2]. Sodium CT was acidified by ion exchanging with an aqueous solution of HCl at pH of 2.0 for several times to remove Na+. 

Pure titanium dioxide was obtained by hydrolyzing the titanium isopropoxide. Thin-layer oxide supports were prepared by grafting the y-alumina (Harshaw, A1 3996) with a non aqueous solution of Ti[OCH(CH3)j4 in THF in Ar flow, followed by hydrolyzing, drying at 393 K and calcining at 623 K and 773 K in air (S h). Two y-alumina supports, calcined at 873K and 1073 K, were used to prepare 6% and 3% TiOj/AljOj, respectively. 

The importance of this synthetic route has been shown in the preparation of anhydrous tris-j6-diketonates of lauthanides, the hydrated forms of which obtained from aqueous solutions tend to decompose into hydroxy-derivatives. By nsing isopropoxides or ethox-ides as starting materials and removing the liberated alcohol by fractionation as a lower boiling azeotrope with a solvent such as benzene, volatile stable intermediate products may be obtained. The alkoxide groups in these mixed derivatives are much more reactive than the j6-diketonate ligands, as illustrated by Eqs (2.220)-(2.223) ... 

---