Zirconium acetylacetonate

Zirconium Acetylacetonate Sihca supported Zr(lV) acetylacetonate surface complex [(=SiO)3Zr(acac)] (acac = MeCOCHCOMe) catalyzes transesterification reactions [114]. Satisfying silsesquioxane models have been reported [2, 114]. 

In contrast, allyl methacrylate is produced by the esterification of methacrylic acid and allyl alcohol (13), or by the transesterification of allyl alcohol with an ester of methacrylic acid, preferably with methyl methacrylate. The latter reaction is catalyzed with zirconium acetylacetonate (14). The esterification reactions are shown in Figure... 

Zirconium acetylacetonate can react in a similar way and as noted previously, surface analysis of zirconium acetylacetonate derivatives on corona-discharged polypropylene has shown bonding to the surface carboxyl groups [6]. 

Zirconium propionate Zircoaluminates Zirconium acetylacetonate, zirconium methacrylate... 

Krohn showed that the oxidation of phenols by TBHP was mediated by zirconium acetylacetonate (Eq. 29), although [Mo(02)20]py HMPT or ClTi(0-i-Pr)3 was found to be superior [33]. 

Tetraethoxysilane (TEOS) and zirconium acetylacetonate Zr(acac)4 were used as precursors to prepare gels with molar ratios Zr/Si = 0.05 or 0.1. These samples were compared to the reference with Zr/Si = 0. 

Gelation times and gel aspects are summarized in Table 1. As shown in this table, an important decrease in the gelation time (tg) is recorded when a small amount of Zr(acac)4 is added (case of the molar ratio Zr/Si = 0.05). A similar behaviour is observed if a larger amount of zirconium acetylacetonate is used (Zr/Si = 0.1). However, for this ratio the gel is harder. The presence of acetylacetonate ligands in the solution could take a prominent part in gelation time, and the increase of their number influences especially the gel aspect, due to their chelating character [13]. 

The solvents most frequently mentioned as dissolving the metal acetylacetonates are benzene, ethanol, chloroform, carbon tetrachloride, carbon disulfide, and petroleum ether. Since the solubility in petroleum ether is much less than in benzene, the former is frequently added to a saturated solution in the latter to effect crystallization. Hatch and Sutherland13 give data on the solubilities of sodium, potassium, magnesium, beryllium, and aluminum acetylacetonates in benzene, cyclohexane, and n-hexane from 0 to 100°. Other solubility measurements are as follows copper(II) acetylacetonate, 0.00338 mol/1. in benzene at 25° 57 zirconium acetylacetonate, 200, 34, 47, and 56 g./l. in absolute ethanol, carbon disulfide, carbon tetrachloride, and acetylacetone, respectively, at 25°.4 Recent data by Blanch58 are assembled in the following table. 

The process is initiated at terminal hydroxy groups and favoured by the spiral-like structure of polysiloxanes. Replacement of the hydroxy groups by methyl, or blocking them by chelation to copper, iron or zirconium acetylacetonates, considerably decreases the rate of decomposition of the polymer and increases its thermal stability (Table 9). However, pronounced crosslinking even at moderate temperatures was observed in the polymer stabilized by transition metal compounds. The effect of the metal additives during thermal ageing is associated with reactions leading... 

At this point Ziegler and his coworkers carried out experiments on the effects of adding various other metal compounds to triethylaluminum. In one of these experiments with zirconium acetylacetonate, ethylene, and triethylaluminum, they found, to their surprise, an autoclave filled with a solid cake of snow-white polyethylene (1. ) Further work revealed that aluminum alkyls in conjunction with certain transition metal compounds of Groups IV-VI, as well as uranium and thorium, were active ethylene polymerization catalysts. Ultimately, Ziegler catalysts were described to be the product of reaction of metal alkyls, aryls, or hydrides of Groups I-IV and certain transition metal compounds of Groups IV-VIII (Reaction 4). The choice of a particular catalyst and experimental conditions is dictated by the structure of the monomer to be polymerized. 

Solvent soluble compounds include zirconium acetylacetonate, zirconium methacrylate, and the family of neoalkoxyl zirconates. Some commercially available zirconates are shown in Table 3. Wang [8] has described the synthesis of a soluble linear Schilf base zirconium-based coordination polymer (N, N, N", A "-tetrasalicylidene-3,3 -diaminoben-zidene) zirconium, and other hybrid copolymers, and has demonstrated improved adhesion on glass and aluminum substrates for poly(methyl methacrylate), polyethylene, and polypropylene when used as hot-melt compounds. 

It is obtained by ROP of the monomer p-dioxanone. The process requires heat and an organometallic catalyst like zirconium acetylacetonate or zinc L-lactate. The reaction is shown in Figure 1.11. 

Directions are given for the preparation of the following beryllium acetylacetone (synthesis 5), aluminum"acetylace-tone (synthesis 9), bis[tris(2,4-pentanediono)titanium(IV)] hexachlorotitanate(IV) (synthesis 34), zirconium acetylacetone (synthesis 35), and thorium acetylacetone (synthesis 36). 

Nomenclature. The nomenclature of the metallic derivatives of the 1,3-diketones in the literatme has not been definitive. These compounds have usually been called acetylacetonates or derivatives of acetylacetonates, e.g., zirconium acetylacetonate, beryllium benzoylacetonate, and lanthamun trifluoroacetylacetonate. A better nomenclature is based on the extensions of the International Union of Chemistry (I.U.C.) rules for inorganic nomenclature to include all types of coordination compounds. Thus, the foregoing names become tetrakis(2,4-pentane-diono) zirconium, bis(l-phenyl-l,3-butanediono)-beryl-lium, and tris(l,l,l-trifluoro-2,4-pentanediono)lanthanum. Further examples are... 

Zirconium acetylacetonate was first prepared by Biltz and Clinch by the reaction of zirconyl nitrate and sodium acetylacetonate in water solution. The compound was crystallized as the 10-hydrate from a slightly acid solution and dehydrated by several crystallizations from alcohol. Von Hevesy and Logstrup later developed a method for the preparation of hafnium acetylacetonate that has been found applicable to the synthesis of the zirconium compound and this forms the basis of the present procedure. 

B. Preparation of Zirconium Acetylacetonate. Five and eight-tenths grams of the crystallized zirconium oxychloride... 

Zirconium acetylacetonate 10-hydrate effloresces in air and may be completely dehydrated in a vacuum of 0.1 mm. The anhydrous salt sublimes slowly with some decomposition in vacuo at about 140° and melts at 194.5 to 195° with decomposition. The acetylacetonate reacts with alcohol. Its solubility at 25° per liter in other organic solvents is as follows carbon disulfide, 30 g. carbon tetrachloride, 47 g. acetylacetone, 56 g. ethylene dibromide, 44 g. benzene, approximately 200 g. Both the hydrate and the anhydrous compound give a red color with carbon disulfide on standing. This is also true of hafnium acetylacetonate but not of the thorium compound. 

Zirconium acetylacetonate. See Zirconium tetraacetylacetonate Zirconium ammonium carbonate. See Ammonium zirconium carbonate Zirconium anhydride. See Zirconium oxide Zirconium basic carbonate. See Zirconium carbonate basic... 

Following the discovery of the a-olefin synthesis, a systematic investigation of metal compounds was undertaken. In 1953, zirconium acetylacetonate was used as a cocatalyst. Instead of liquid a-olefins, a voluminous white precipitate was produced. This new substance was a polymer of ethylene. Ten years later, millions of pounds of this Ziegler-type polyethylene were made in the United States alone. In addition to the zirconium compound, other transition metal compounds were found to be effective cocatalysts. Today titanium tetrachloride or trichloride is used as the cocatalyst with an organoaluminum compound. 

The polymerization of p-dioxanone has been described in several references (Doddi et al, 1977 Shalaby and Koelmel, 1984 Jamiolkowski et al, 1989). As described above, highly purified p-dioxanone monomer is polymerized in the presence of an organometallic catalyst such as diethyl zinc or zirconium acetylacetone to obtain high molecular weight, fiber forming polymer (Figure 5). 

Polydioxanone is a colorless, crystaUine, biodegradable synthetic polymer. Chemically, it is a polymer of multiple repeating ether-ester units. It is obtained by ringopening polymerization of the monomer p-dioxanone. The process requires heat and an organometallic catalyst as zirconium acetylacetone or zinc L-lactate. Polydioxanone is characterized by a glass transition temperature in the range of 10 and 0°C and a crystallinity of about 55%. It is generaUy extruded into fibers however, to avoid its... 

Method of synthesis ring-opening polymerization of p-dioxanone in the presence of organometallic catalyst (e.g., zirconium acetylacetone) Li, Y Whng, X-L, Yang, K-K Wang, Y-Z, Polym. Bull., 57,873-880, 2006. 

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