Studies with zirconium-aluminum

In a brief preliminary note Heine, Cottle, and Van Mater reported comparative results showing that zirconium tetrachloride is generally superior to aluminum chloride for the Friedel-Crafts p-acetylation of toluene with acetyl chloride. However, the results were less consistent with ZrCl, than with AICI3. Gore and Hoskins studied the Friedel-Crafts reaction of benzoyl chloride with anthracene in ethylene dichloride at 0° in the presence of 14 different catalysts. The best yields of very pure 9-benzoylanthracene were with zirconium tetrachloride (97% yield after lihrs.) and with aluminum chloride (86% yield after U hrs., 99% yield after 99 hrs.). 

A majority of studies have been concerned with anodizing aluminum and its alloys, " " " although tantalum, " titanium, zirconium, and other transition and coinage metals have been of interest. The Italian school under Conte has been particularly active in these investigations which have mainly centered on nitrate melts, over the temperature interval 343-723 K. A bisulfate mixture is used in a Japanese commercial process. " Table 4 shows some of the melt systems that have been studied. 

The vapor-phase esterification of ethanol has also been studied extensively (363,364), but it is not used commercially. The reaction can be catalyzed by siUca gel (365,366), thoria on siUca or alumina (367), zirconium dioxide (368), and by xerogels and aerogels (369). Above 300°C the dehydration of ethanol becomes appreciable. Ethyl acetate can also be produced from acetaldehyde by the Tischenko reaction (370—372) using an aluminum alkoxide catalyst and, with some difficulty, by the boron trifluoride-catalyzed direct esterification of ethylene with organic acids (373). 

In this case study, a zirconia-alumina membrane has been developed using the sol-gel technique with and without support.6-7 The porous ceramic was prepared to fabricate the membrane support. A thin film of aluminum and zirconium were formed on the porous ceramic support. Unsupported membrane was also prepared. The unsupported membrane was not strong enough to hold a high-pressure gradient it was very fragile and not useful... 

In related studies, Cp2ZrCl2 has been found to catalyze at room temperature an aluminum hydride (i-Bu2AlH) reduction of CO to linear Ci-C5 alcohols (430). The system involves reaction of complex 55 with CO, which precipitates the starting zirconium(IV) complex and leaves a yellow solution, that on hydrolysis yields the alcohols. Toluene solutions of Cp2Ti(CO)2 complex under H2/CO effect Eq.(69), i.e., a homogeneous stoichiometric hydrogenation of carbon monoxide to methane (426). 

Recent advances in the development of well-defined homogeneous metallocene-type catalysts have facilitated mechanistic studies of the processes involved in initiation, propagation, and chain transfer reactions occurring in olefins coordi-native polyaddition. As a result, end-functional polyolefin chains have been made available [103].For instance, Waymouth et al.have reported about the formation of hydroxy-terminated poly(methylene-l,3-cyclopentane) (PMCP-OH) via selective chain transfer to the aluminum atoms of methylaluminoxane (MAO) in the cyclopolymerization of 1,5-hexadiene catalyzed by di(pentameth-ylcyclopentadienyl) zirconium dichloride (Scheme 37). Subsequent equimolar reaction of the hydroxyl extremity with AlEt3 afforded an aluminum alkoxide macroinitiator for the coordinative ROP of sCL and consecutively a novel po-ly(MCP-b-CL) block copolymer [104]. The diblock structure of the copolymer... 

Pal and Kapoor74 have studied the reactions of isopropoxides of aluminum, titanium and zirconium with benzo- and phenylaceto-hydroxamic adds in anhydrous benzene. Solid products of the types Al(OPr )3 L and M(OPri)4 L (where M = Ti or Zr and L is the hydroxamic acid) have been isolated all the aluminum and zirconium products are white in colour whereas titanium ones are yellow. The mixed isopropoxide hydroxamates interchange their isopropoxy group with r-but-oxy groups, yielding r-butoxide products. 

Excision reactions are sometimes accompanied by redox chemistry. For example, dissolution of the 2D solid Na4Zr6BeCli6 in acetonitrile in the presence of an alkylammonium chloride salt results in simultaneous reduction of the cluster cores (144). Here, the oxidation product remains unidentified, but is presumably the solvent itself. As a means of preventing such redox activity, Hughbanks (6) developed the use of some room temperature molten salts as excision media, specifically with application to centered zirconium-halide cluster phases. A number of these solids have been shown to dissolve in l-ethyl-2-methylimidazolium chloride-aluminum chloride ionic liquids, providing an efficient route to molecular clusters with a full compliments of terminal chloride ligands. Such molten salts are also well suited for electrochemical studies. 

Both aluminum oxide and zirconium oxide are catalytically interesting materials. Pure zirconium oxide is a weak acid catalyst and to increase its acid strength and thermal stability it is usually modified with anions such as phosphates. In the context of mesoporous zirconia prepared from zirconium sulfate using the S+X I+ synthesis route it was found that by ion exchanging sulfate counter-anions in the product with phosphates, thermally stable microporous zirconium oxo-phosphates could be obtained [30-32]. Thermally stable mesoporous zirconium phosphate, zirconium oxo-phosphate and sulfate were synthesized in a similar way [33, 34], The often-encountered thermal instability of transition metal oxide mesoporous materials was circumvented in these studies by delayed crystallization caused by the presence of phosphate or sulfate anions. 

Allan (A7) during his studies of ashed plant materials also investigated interferences. Using an air-acetylene flame, sodium, potassium, calcium, magnesium, and phosphate had no effect. In the air-coal gas flame, as employed by Elwell and Gidley (E2), recoveries of iron were only 80-90% when the test solutions contained an excess of calcium, copper, aluminum, titanium, and zirconium. With silicon added, iron recovery was 26%. Owing to incomplete vaporization of iron in the flame, sensitivities attained are higher in the air-acetylene flame and lower in the air-coal gas flame. Since iron is subject to oxidation in the flame, fuel-rich flames are preferable. 

The above study shows clearly that alloying titanium of technical purity (alloy BT1-0) with silicon may ensure tensile strength around 1050 MPa at around 9 % of elongation (Fig. 1). It means that a margin to enhance these properties with alloying by other elements like aluminum and zirconium traditionally introduced to improve high temperature properties of titanium. 

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