Pentane-2,4-dione structure

The adducts formed with acetone, cyclopentanone, cyclopentanedione, 2,4-pentane-dione or 3-methyl-2,4-pentanedione (See Structure strOl, p. S-l, R=CH3CO.CH2, etc.) form insoluble potassium salts (M=K), but these are highly explosive and shock-sensitive and should not be isolated, but handled only in solution. 

Previous works [98] have also revealed that (i) the nature of the precursors or (ii) the annealing kinetic parameters play a significant role for the stabilization of the metastable phase. Indeed, for chloride-based precursors, the pyrochlore structure is directly obtained. This is explained by the high affinity of Q anions relative to Ln ", which prevents the formation of the complex with 2,4-pentane-dione and thus the formation of a homogeneous gel. In addition, for the kinetic aspect, the layered perovskite phase is favored for rapid annealing or quenching directly at 950 °C. 

Bekiaris et al. have studied the reaction of fluorinated pentane-2,4-diones and phosphanes and have reported the formation of bicyclic compounds and phosphaadamantanes <1997CB1547>. Compounds 167 and 168 were formed in a diasteroselective manner (Scheme 13) and their structures were determined by single crystal X-ray structure analysis. 

Dimerization and condensation of pentane-2,4-dione by molybdenum(VI) oxide tetrachloride (MoOC14) affords l,3,5,7-tetramethyl-2,4,6,8-tetraoxa-adamantane, the structure of which is determined by elemental analysis, IR, mass, and PMR spectroscopy.188... 

Fig. 14 Structure of the pentane-2,4-dione-diethylamine adduct (taken with permission from Emsley et al., 1986b).

Buemi (1990) has also carried out semi-empirical AMI calculations on 3-(4 -biphenyl)pentane-2,4-dione whose molecular parameters have been fully determined by X-ray diffraction (Emsley et al., 1988b). The most stable configuration predicted by theory was not that found in the crystal structure. The calculated hydrogen-bond length (7 o o 275.9 pm) differed from the observed value (241.1pm). The conclusion was reached that the short hydrogen bond observed in the crystal is a peculiarity of the solid state. 

Hydroxy-4-methyl-4-penten-2-one (1) was prepared from 3-chloro-mesityl oxide using a modified procedure from the literature [ref.4], A reference sample of 4-methyl-4-penten-2,3-dione (2) was prepared from using the copper acetate method [ref.2], 4-methyl-pentan-2,3-dione (3) was purchased from Wiley Co. 2-Hydroxy-4-methyl-4-penten-3-one (4) was synthesized in 30% yield from 2-propenyl-magnesium bromide and 2-hydroxy-propionitrile in tetrahydrofurane. The structures of all compounds were confirmed by H-. C-NMR- and mass spectroscopy [ref. 5],... 

The bis-adducts of pentane-2,4-dione with benzamidrazonium iodide, 76 [R = Ph(H2N+ = )C, I ], possessing the open-chain structure in the solid state, exhibits the equilibrium 76A 76B in solution in CDCl3-(CD3)2SO... 

Acetylacetone (pentane-2,4-dione) reacts with sodium hydroxide to give water and the sodium salt of a carbanion. Write a complete structural formula for the carbanion, and use resonance forms to show the stabilization of the carbanion. 

Reaction of MeC0CH2C02Et with HNO2, then a combination of Zn/AcOH and pentane-2,4-dione gave a pyrrole, C11H15NO3. Deduce the structure of the pyrrole, write out a sequence for its formation, and suggest a route whereby it could then be converted into 2,4-dimethyl-3-ethylpyrrole. 

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