Acetylacetone preparation

The PZT and Nb-doped PZT (PZTN) ceramics were synthesized from triol sol-gel-derived powders [95]. The reagents used were zirconium(IV) propoxide and acetylacetone prepared in a dry nitrogen atmosphere. The mixture was refluxed in an oil bath at 90 °C for 2 h. The solution was then cooled down to room temperature before adding titanium(IV) isopropoxide, lead(II) acetate trihydrate, and l,l,l-tris(hydroxymethyl)ethane. The obtained gels were dried at 120 °C and thermally treated at different temperatures up to 600 °C. 

Dimethylpyrazole (III) may be prepared from acetylacetone (I) and hydrazine (II) (produced from hydrazine sulphate and aqueous alkali). The reaction may be represented as ... 

Attention should be paid to the fact that the ratio of Pd and phosphine ligand in active catalysts is crucial for determining the reaction paths. It is believed that dba is displaced completely with phosphines when Pd2(dba)3 is mixed with phosphines in solution. However the displacement is not eom-plcte[16]. Also, it should be considered that dba itself is a monodentate alkene ligand, and it may inhibit the coordination of a sterically hindered olefinic bond in substrates. In such a case, no reaction takes place, and it is recommended to prepare Pd(0) catalysts by the reaction of Pd(OAc)2 with a definite amount of phosphinesflO]. In this way a coordinatively unsaturated Pd(0) catalyst can be generated. Preparation of Pd3(tbaa)3 tbaa == tribenzylidene-acetylacetone) was reported[17], but the complex actually obtained was Pd(dba)2[l8],... 

The reaction of methyl propionate and formaldehyde in the gas phase proceeds with reasonable selectivity to MMA and MAA (ca 90%), but with conversions of only 30%. A variety of catalysts such as V—Sb on siUca-alumina (109), P—Zr, Al, boron oxide (110), and supported Fe—P (111) have been used. Methjial (dimethoxymethane) or methanol itself may be used in place of formaldehyde and often result in improved yields. Methyl propionate may be prepared in excellent yield by the reaction of ethylene and carbon monoxide in methanol over a mthenium acetylacetonate catalyst or by utilizing a palladium—phosphine ligand catalyst (112,113). 

The reaction of a mixture of 1,5,9-cyclododecatriene (CDT), nickel acetylacetonate [3264-82-2], and diethylethoxyalurninum in ether gives red, air-sensitive, needle crystals of (CDT)Ni [12126-69-1] (66). Crystallographic studies indicate that the nickel atom is located in the center of the 12-membered ring of (CDT)Ni (104). The latter reacts readily with 1,5-cyclooctadiene (COD) to yield bis(COD) nickel [1295-35-8] which has yellow crystals and is fairly air stable, mp 142°C (dec) (20). Bis(COD)nickel also can be prepared by the reaction of 1,5-COD, triethylaluminum, and nickel acetylacetonate. 

A family of Ti(III) derivatives roughly parallels those of Ti(IV). Titariium(III) chelates are known, eg, titanium ttisacetylacetonate [14284-96-9] prepared in benzene from titanium trichloride, acetylacetone, and ammonia (185). This deep-blue compound is soluble in benzene but insoluble in water. 

Decomposition of the diazoimide (551) by heating in the presence of copper acetylaceton-ate also generated a ketocarbene (552). This undergoes an intramolecular condensation to give the anhydro-4-hydroxy-3-methyl-4-p-nitrophenyl-2-phenyloxazolium hydroxide (553), which cannot be prepared by more classical means (75CL499). 

This is by far the most stable and best-known oxidation state for chromium and is characterized by thousands of compounds, most of them prepared from aqueous solutions. By contrast, unless stabilized by M-M bonding, molybdenum(III) compounds are sparse and hardly any are known for tungsten(III). Thus Mo, but not W, has an aquo ion [Mo(H20)g] +, which gives rise to complexes [MoXg] " (X = F, Cl, Br, NCS). Direct action of acetylacetone on the hexachloromolybdate(III) ion produces the sublimable (Mo(acac)3] which, however, unlike its chromium analogue, is oxidized by air to Mo products. A black cyanide,... 

Several variations of the Feist-Benary reaction furnish substituted furans as products. The following three examples provide synthetically useful alternatives to the standard reaction conditions. One method is based on the reaction of a sulfonium salt with a P-dicarbonyl compound. For example, reaction of acetylacetone (39) with sulfonium salt 38 in the presence of sodium ethoxide yields 81% of trisubstituted furan 40. This strategy provides a flexible method for the preparation of 2,3,4-trisubstituted furans. 

Combination of nickel bromide (or nickel acetylacetonate) and A. A -dibutylnorephcdrinc catalyzed the enantioselective conjugate addition of dialkylzincs to a./Tunsaturated ketones to afford optically active //-substituted ketones in up to ca. 50% ee53. Use of the nickel(II) bipyridyl-chiral ligand complex in acetonitrile/toluenc as an in situ prepared catalyst system afforded the //-substituted ketones 2, from aryl-substituted enones 1, in up to 90% ee54. 

The corresponding tri- and hexa-fluoroacetylacetonates may be similarly prepared. The stability of the acetylacetonate is such that not only can it be resolved on passage through a column of D-lactose, but the enantiomers retain their integrity on nitration or bromination. 

Monoalkyltin(IV) compounds can be prepared under suitable conditions from tindl) compounds (44-46). Tin(II) bis(acetylacetonate) (acac) and related compounds react readily with a variety of alkyl bromides or iodides, to give the product RSn(acac)2X, e.g.,... 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Highly active gold catalysts can be prepared by an appropriate selection of preparation methods such as CP, DP, DR, and SG with dimethyl Au(III) acetylacetonate, depending on the kind of support materials and reactions... 

The mixed support Al203 Zr02 (AlZr) was prepared by wet impregnation of AI2O3 with Zr(C5H702)4 dissolved in toluene After evaporation of the solvent and drying at 373 K, the acetylacetonate was decomposed under O2 up to 773 K (0.5 K/min). 

Transition-metal mixed oxides active in combustion catalysis have been prepared by two main procedures i) classical coprecipitation / calcination procedures starting from metal nitrates and/ or alkoxides ii) preparation based on the supercritical drying of gels prepared from organic complexes (alkoxides, acetylacetonates or acetates), producing aerogels . Details on the second preparation can be found in Ref. 13. 

The same behaviour has been found with Cu/ZrOa. A highly dispersed Cu phase was obtained at the surface of zirconla by reacting the support with Cu acetylacetonate [19]. This procedure yields an active catalyst. This catalyst was selective for Na formation at low temperature (< 550 K), but produced only NO2 when the temperature becomes higher than 650 K. However, the same type of catalyst prepared from sulfated zirconia did not produce NO2 but selectively reduces NO to N2 whatever the temperature, with a yield of about 40% at 670 K, and a GHSV of 70000 h l, using only 300 ppm of decane. 

In this paper we report (i) the catalytic activity for SCR of VOx/Zr02 samples prepared by various methods (adsorption from aqueous metavanadate solutions at different pH values, dry impregnation, and adsorption from VO(acetylacetonate)2 in toluene), (ii) sample characterization (nuclearity, dispersion and oxidation state) by means of XPS, ESR and FTIR and (iii) the nature and reactivity of the surface species observed in the presence of the reactant mixture. Catalytic results are here reported in full. Characterization data relevant to the discussion of the catalytic activity will be given, whereas details on the catalysts preparation and... 

VOx/ZrOz samples were prepared by three methods (i) adsorption from a solution of ammonium metavanadate (AV) at pH values from 1 to 4, adjusted by nitric acid, (ii) dry impregnation with AV solutions and (iii) adsorption from a solution of VO(acetylacetonate)2 in toluene. 

V0x/Zr02 catalysts were designated as ZVx(y)pHz, where x gives the analytical vanadium content (weight percent), y specifies the preparation method (a, adsorption, i, impregnation or acac, acetylacetonate) and z the AV solution pH. The V-content was determined by atomic absorption (Varian Spectra AA-30) after the sample had been dissolved in a concentrated (40%) HF solution. 

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