Zirconium isopropoxide

Zirconium alkoxides behave similarly in regard to thermal stability. The series zirconium methoxide [28469-78-5] zirconium ethoxide [18267-08-8] zirconium isopropoxide [2171 -98 ] zirconium /r /f-butoxide [2081 -12-1] shows decreasing thermal stability. 

No formation of bimetallic complexes is observed on MoO(OPr )4 dissolution in the alcohol solutions of zirconium isopropoxide, due presumably to the high stability of the structure of the latter. A very unusual complex of Zr3Mo,024(OPri)12( PrOH)4 composition precipitates slowly from solutions of isopropoxides in hexane subjected in advance to evacuation to dryness and redissolution repeated three times. The structure of the complex obtained is very close to that of the zirconium methoxide hydrolysis product, Zr O OMe) (Fig. 5.1 c) [901]. The formation of a complex very rich in oxoligands is presumably due to the trend of ZrCOPhV PrOH to form oxocomplexes on desolvation (see Section 12.12). 

The lamellar form of mesoporous zirconium oxide was prepared using dodecylamine (DA) as the surfactant. In a typical synthesis zirconium isopropoxide (0.01 mol) was added to a solution of the dodecylamine (DA) (0.03 mol) in propan-l-ol... 

Sol-gel processing techniques have largely been applied to main group alkoxides, particularly Si and Al, but increasingly studies have dealt with early transition metal elements such as Ti and Zr. The preparation of metal alkoxides has been reviewed extensively.46 18 Self-condensation of alkoxides can occur, depending on the steric demands of the alkoxide group for example, Ti methoxide, ethoxide, and isopropoxide are tetrameric, trimeric, and dimeric, respectively,49 while the zirconium isopropoxide is tetrameric.50... 

From Zirconium Isopropoxide and Yttrium Acetylacetonate by Flame Pyrolysis Properties 9 mol% yttria, BET specific surface area 68 rnVg [2206]. 

Zirconium support modification of alumina was performed by adding zirconium, in the form of zirconium isopropoxide, under an inert atmosphere to isopropanol. Alumina was added to this solution, and the mixture stirred at 60 "C for 1 hour. The solvent was removed under a vacuum of 3kPa (a) with a jacket temperature of 95 °C. The resultant modified support was subsequently calcined at 600 C for 2 hours to obtain a protected modified catalyst support. The amount of precursor was found to be 0.1 Zr atoms/nm fresh support. 

The subsequent zirconia sample was obtained by hydrolysis of zirconium isopropoxide in aqueous ethanol in the presence of NH4OH as the catalyst. Water and the organic solvent were removed from the zirconium hydrogel by drying in air at 150 °C. 

This work involves the modification of silica-zirconia (33 mol% zirconia) via sulphation and phosphation processes and a comparison of the resultant acidic properties. Mixed oxides were prepared by the sol-gel method which allowed homogeneous mixing of the two component oxides at room temperature. Procedure involved pre-hydrolysis of TEOS with nitric acid and water followed by the addition of zirconium isopropoxide. S Zr and P Zr ratios of 0.20 1, 0.25 1, and 0.30 1 were employed whereby the addition... 

Phosphate and sulphate modifiers were incorporated by the addition of appropriate amounts of 0.01 M sulphuric or phosphoric acid to a pre-calcined aerogel followed by further calcination at 873 K. Samples are labeled as X-SiZr (y) where X refers to either sulphated (S) or phosphated (P) samples, and y refers to the mole ratio of sulphate/phosphate relative to zirconium in the preparation method. For comparison purposes, samples of zirconia and sulphated zirconia were also prepared. This was achieved via precipitation from zirconium isopropoxide (Aldrich 70 wt.%). The same H2O Zr propanol ratios were employed as used during the preparation of the mixed oxides. A sulphated zirconia, prepared by the use of sulphuric acid as hydrolysis catalyst was prepared for comparative purposes and had a nominal S Zr ratio of 0.30 1. A further sample was prepared where segregation of components was induced by thermal treatment by calcination at 1373 K for 6 h.of the non-treated SiZr (0)... 

Mesoporous zirconias obtained by hydrolyzing zirconium isopropoxide at low pH (.3) in presence of alkyl straight-chain surfactant are disordered composite materials that develop high surface areas and mesoporosity. They differ essentially from mesoporous materials obtained by templating since their surface area and porosity are available in the presence of the surfactant. Another building mechanism, accounting for this difference is suggested. 

Fractional distillation of the more volatile este CH3COOR in Eq. (5.15) is required to complete the reaction. Transestoification reactions have been used for the preparation of alkoxides of various metals including Zr, Ti, Ta, Nb, Al, La, Fe, Ga, and V. For example, zirconium rerf-butoxide has been prepared from the reaction between zirconium isopropoxide and terf-butyl ester followed by distillation of isopropyl acetate ... 

Contrary to earlier observations, Saxena et al have reported the successful synthesis of even the tetrakis derivatives in the step-wise reactions of zirconium isopropoxide with acetylacetone, benzoylacetone, dibenzoylmethane and ethylaceto-acetate. Ebulliometric molecular weight determinations in benzene revealed the monomeric behaviour of all zirconium /6-diketonate derivatives except the triisopropoxide mono-j6-diketonate derivatives, which show dimeric behaviour. The bidentate character of the /6-diketonate ring in zirconium compounds has been adduced from infrared spectra which show the carbonyl bands in the lower region (1580-1601 cm ), and the hexacoordinated dimeric structure (/S-dik)(01V)2Zr(/z-0Pr )2Zr(0lV)2()8-dik), with isopropoxide bridging has been suggested for [ Zr(OIV)3()S-dik) 2] derivatives. 

The reactions of zirconium isopropoxide with fatty acids (caproic, lauric, palmitic, and stearic) were found to be similar to those of titanium isopropoxide, except that the tris-product, Zr(OPr )(OOCR)3 was more stable than the titanium analogue and could be isolated at lower temperatures in 1 3 molar reactions. However, it reacted very slowly with a further mole of the acid, and the tetracarboxylate so formed reacted readily with Zr(OPr )(OOCR)3 yielding the basic carboxylate (RC00)6Zr20 ... 

All the above reactions have been found to be quite facile and have been mostly carried out with metal isopropoxides and also with ethoxides in some cases. The 1 1 molar reaction of the alcoholate, Zr(OPr )4.I OH with CH3COCI showed that the zirconium isopropoxide moiety is more reactive than the coordinated isopropyl alcohol molecule. 

The reaction of ZiCU with KAl(OPr )4 in 1 2 molar ratio appears to proceed to the formation of Cl2Zr Al(OPr )4 2, which on being treated with KOPr (2 moles) yields (OPr )2Zr Al(OPr )4 2 (Eq. 3.39) which is also the end product of the reaction between zirconium isopropoxide and excess of aluminium isopropoxide (Eq. 3.8). 

Relatively few structures of alkoxo zirconium compounds have been reported. Although a dimeric structme [Zr2(/z-OlV)2(OlV)6(l OH)2] had been proposed for the crystalhne zirconium isopropoxide isopropanolate many years ago the edge-shared bi-octahedral structure was not properly determined by X-ray crystallography until 1990. An interesting feature of this structme is the location of the coordinated isopropanol molecules which are each linked by a hydrogen bond to the terminal... 

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