In acetylacetone

Gas-phase grafting (GG) is characteristic in that gold can be deposited even on the acidic surfaces, such as activated carbon and on Si02 [27]. The vapor of gold acac complex is adsorbed on the support powder probably through the interaction of electron-rich oxygen atoms in acetylacetonate and then calcined in air to decompose it into metallic gold particles. 

The exchange reaction of Tc(acac)3 in acetylacetone solution is described as follows ... 

Hinsen, K. Roux, B., Potential of mean force and reaction rates for proton transfer in acetylacetone, J. Chem. Phys. 1997,106, 3567-3577... 

To indicate the importance of enolization, equilibrium constants for a number of substrates are shown in Table 10.1. These equilibrium constants are only approximate, and they do depend very much on the solvents employed. Nevertheless, we can see that the equilibrium constant K = [enol]/[keto] is very small for substrates like acetaldehyde, acetone, and cyclohexanone, with only a few molecules in every million existing in the enol form. However, in ethyl acetoac-etate, enol concentrations are measured in percentages, and in acetylacetone the equilibrium constant indicates the enol form can be distinctly favoured over the normal keto form. In hexane solution, only 8% of acetylacetone molecules remain in the keto form. 

A report (18) by Djordjevis, Lewis, and Nyholm in 1959 that reaction of copper acetylacetonate with N204 afforded bis-(3-nitro-2,4-pentanediono)copper-(II) (V), spurred our early efforts in acetylacetonate chemistry. The nitro-chelate was thoroughly characterized. 

The tris and bis complexes of acetylacetone (2,4-pentanedione) (167) with chromium(III) have been known for many years (168,169).739 The tris compound is generally prepared by the reaction of an aqueous suspension of anhydrous chromium(III) chloride with acetylacetone, in the presence of urea.740 Recently a novel, efficient synthesis of tris(acetylacetonato)chromium-(III) from Cr03 in acetylacetone has been reported.741 The crystal structure of the tris complex has been determined.744 A large anisotropic motion was observed for one of the chelate rings, attributed to thermal motion, rather than a slight disorder in the molecular packing. 

Although the methyl groups in acetylacetonate complexes retard some reactions by steric hindrance, they provide some electronic enhancement in reactions with electrophiles and furthermore protect the donor oxygen atoms from electrophilic attack. These properties have been discerned by a comparison of the numerous reactions of acetylacetone complexes with the relatively few successful reactions of complexes of formylacetone and malondialdehyde. 

Figure 1 Bond distances and angles in acetylacetone (reproduced with permission from J. Am. Chem. Soc., 1983,105, 1584)...

The methyl groups in acetylacetone chelates appear to enhance electronically the reactivity of the central carbon position and this overcomes the steric retardation which they cause. The for-mylacetone and malondialdehyde chromium(III) chelates undergo the typical bromination and nitration reactions more slowly than does the acetylacetone chelate and the products are less stable... 

Intramolecular proton transfer rates in acetylacetone have been calculated.148... 

There have been few other examples of secondary deuterium IEs on CH acidity. One reason is their low acidity (carbocations excepted), so that their conjugate bases are not so readily accessible. Another reason is that the titration methods are less applicable, because proton-transfer equilibrium is not established instantaneously . Nevertheless, measurement of IEs in acetylacetone, malononitrile, and related acids ought to be feasible, and they might be larger than the secondary IEs reported here because the deprotonation of these acids can involve rehybridization. 

A computational study of intramolecular proton transfer in acetylacetone has been carried out.289... 

Ichinaka et al. [309] determined these elements in acetylacetone extracts of potable waters by high performance liquid chromatography. 

I. Matanovic et al., Exploring the potential energy surface for proton transfer in acetylacetone. Chem. Phys. 306, 201-207 (2004)... 

Alkylation of hydroxyazines follows the usual azine behavior with preference for N-alkylation as in the fused hydroxypyridine (11) (72AP833). In the fused uracil (12), using diazomethane or dimethyl sulfate, a mixture of N,N-dimethylated (13) and N,0-dimethy-lated (14) products is obtained. On heating the mixture in acetylacetone in the presence of sodium iodide, the O-methyl isomer is converted into its N-isomer, a type of rearrangement well established in azines (67T675). 

Cdln204 In acetylacetonate + Cd acetate Acetylacetone, methanol Air Glass, A1203 (710 K.)... 

Chloroformates, carbonyl chlorides and acid chlorides are converted into the corresponding fluorides 1 in excellent yield upon treatment with potassium fluoride in the presence of 18-crown-6 at room temperature. Fluoroformates are also synthesized from chloroformates by fluorination with potassium fluoride in acetylacetone at 60"C under UV irradiation, with potassium fluoride in nitrobenzene,- with potassium fluoride in the absence of a solvent at temperatures in the range 100-250 and with thallium(I) fluoride. 

Aqueous-Phase Polymerization of Butadiene Initated by Cobalt (in) Acetylacetonate... 

Sol-gel processes are also suitable for lanthanide oxide formation, as could be shown by the use of Tb(acac)3 and Dy(OBu- )3 in acetylacetone" . Tb203 crack- and pine-hole-free, dense and smooth microstructured buffer layers were produced on nickel tapes by a reel-to-reel continuous sol-gel process. The authors report that the film properties can be strongly influenced by solution components, temperature, time and atmosphere. Nanocrystalline mesoporous dysprosium oxide Dy203 with narrow monomodal pore size distribution can be approached by a combined sol-gel process with a surfactant-assisted templating technique . The spherical Dy203 nanoparticles were formed with aggregations. 

Introduction of a nitro group into a hydrocarbon considerably enhances the thermodynamic acidity of the C—H bond. For example, nitroethane has pK 8.60 [99]. The effect of the nitro group is comparable to the effect of the two keto groups in acetylacetone (pK 8.9) [17]. The nitrocarbanion (or nitronate ion) is strongly stabilized by inductive and mesomeric electron withdrawal. In solution the ionization (73) is slightly complicated by the presence of the aci-nitro isomer, similar to the enolic form of a ketone, viz. 

T3.8.2.3 Obtained in Microemulsion Ammonium hydroxide was added to a solution containing Igepal Co520 (surfactant) and cyclohexane, and the mixture was shaken to obtain a microemulsion. Solutions of zirconium n-propoxide in acetylacetone and n-butanol (l 0.5 3) and of tetraethyl orthosilicate in water and ethanol (1 1 4) were mixed for 3 h, and the mixture was added to the microemulsion with stirring, and hydrolyzed for 3 d. The final concentrations of alkoxides were 0.0075 M, the water surfactant molar ratio was 0.8, and the water alkoxide molar ratio was 10. The powder was washed with acetone and heated at 900°C for 2 h. 

When treated with silver perchlorate or tetrafluoroborate in acetylacetone or ethyl methyl ketone, triphenylbismuth dichloride is converted to tetraphenylbismuth compounds [73JCS(D)1394],... 

The reaction between two equiv. of silver perchlorate and triphenylbismuth dichloride in acetylacetone caused immediate precipitation of silver chloride. After stirring for 30 min, the... 

Rastogi and Rastogi (1980) investigated the oscillatory reaction in acetylacetone/ K.Br03/Mn(III)/H2S04 system and reported oscillations in Br and Mn(III)/Mn(II) and rate of temperature rise,... 

Mavri, J., Grdadolnik, J., Proton transfer dynamics in acetylacetone A mixed quantum-classical simulation of... 

The introduction of substituents into the 3-position in acetylacetone is difficult and in some cases impossible unless the ligand is chelated. For example, the free ligand 3-nitroacetylacetone is unknown, but its chelates, bis(3-nitro-2,4-pentanediono)copper(II) or tris(3-nitro-2,4-pentanediono)-chromium(III), can be obtained by nitration of the metal chelate with a mixture of copper(II) nitrate and acetic anhydride (54). It is possible in this case that the pathway, as well as the rate of the ligand nitration, is altered as a result of chelate formation. 

Molybdenum forms a tris(acetylacetonate), an air-sensitive purple-brown solid prepared by heating Mo(CO)6 or K3MoCl6 in acetylacetone. 

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