Zinc 2,4-pentanedione

Zinc 2,4-pentanedione. See Zinc acetylacetonate Zinc peroxide... 

Bis(2,4-pentanedionato)zinc, obtained by the action of 2,4-pentanedione on zinc compounds, was long believed to be... 

A preferable, three-step, procedure for preparing anhydrous bis(2,4-pentanedionato)zinc, m.p. 127°, in good yields involves (1) the preparation of bis(2,4-pentanedionato)zinc hydrate from zinc sulfate heptahydrate and 2,4-pentanedione in aqueous solution in the absence of heat, (2) conversion of the bis(2,4-pentanedionato)zinc hydrate into a bis (2,4-pentanedionato) zinc-methanol adduct, and (3) decomposition of the methanol adduct. 

To a solution of 100 g. (1 mol) of 2,4-pentanedione and 40 g. (1 mol) of sodium hydroxide in 500 ml. of water is slowly added with stirring a solution of 144 g. (0.5 mol) of zinc sulfate heptahydrate in 500 ml. of water. After the suspension has stood for one hour, the white precipitate is filtered, washed with water, and dried, to give 122 g. (87%) of rather pure bis(2,4-pentanedionato)zinc hydrate with m.p. 138°. The crude product is dissolved in 11. of hot ethyl acetate, to which 50 ml. of 2,4-pentanedione has been added. The solution is filtered hot in order to remove a small amount of high-melting decomposition products. From the cooled solution, 90 g. (64%) of bis(2,4-pentanedionato) zinc hydrate is obtained as needles, m.p. 138 to 140°. 

Bis(2,4-pentanedionato)zinc hydrate forms white crystals which melt at 138 to 140° to a milky liquid. It is rather unstable toward heat, decomposing into mesitylene and an acetate-containing compound of the formula Zn2(CH3C02)(C5H702)3.2 The latter also tends to form on dissolution of the hydrate in cold organic solvents, but this can be prevented by adding 2,4-pentanedione to the solution. The crystal structure of bis-(2,4-pentanedionato)zinc hydrate has been determined recently.3... 

Benzyl [15N]-3,4,5-trimethylpyrrol-2-carboxylate, 94, has been obtained77,79 in 38% yield in the reaction of [15N]-sodium nitrite with benzyl acetoacetate in AcOH at 10-5 °C, during 18 h, followed by addition of 3-methyl-2,4-pentanedione, AcONa, powdered zinc in AcOH, heating the suspension at 60 °C during 1 h, pouring the suspension over ice-water (5°C, 18 h) and recrystallization (Me0H-H20). 

The Clemmensen reduction of j8-diketones (1,3-diketones) is rather complicated. The first step in the reaction of 2,4-pentanedione with zinc amalgam is an intramolecular pinacol reduction leading to a cyclopropanediol. Next the cyclopropane ring is opened in the acidic medium, and a rearrangement followed by a reduction gives the final product, a ketone, with a changed carbon skeleton [924, 925]. The ketone is usually accompanied by small amounts of the corresponding hydrocarbon [924] or an a-hydroxy ketone [925]. 

With dipivaloylmethane, the zinc(II), cobalt(II) (12), and iron(II) complexes (19) are all isomorphous. A three-dimensional x-ray structural determination (12) of the Co(DPM)2 shows a tetrahedral configuration. The copper(II) complex of this ligand and the nickel(II) derivative are planar. The 3-phenyl-2,4-pentanedione derivative of copper(II) also is planar (7). 

Dietsche treated 2,4-pentanedione with methanol and ammonia and obtained diazocine 133 (77USP4001215). Giacalone condensed benzalde-hyde with benzal p-tolylhydrazone (134) in the presence of zinc chloride... 

Conclusive proof comes from an investigation of the unsymmetrically deuteriated bis-2,4-pentanedione complex of zinc. The carbonyl resonance of this complex is a single peak and no splittings were observed. This shows that the anion of the zinc complex is a symmetrical single energy minimum and confirms the conclusion that the enol is a rapidly equilibrating mixture of [12a] and [12b]. 

C20H12F12N20ftZn, cis-Bis(1,1f1,5,5,5-hexafluoro-2,4 pentanedion--ato)bis(pyridine)zinc(II), 39B, 664 C2oHi6CuOft, Copper(II) benzoylacetonate, 31B, 383 C20H1208Th, Tetrakis(trifluoroacetylacetonato)thorium(IV), 38B, 826... 

Dissolve 10 g 2,4-pentanedione and 4 g NaOH in 50 cm water. Add the solution slowly and with stirring, to a solution of 14.4 g zinc sulphate hepthydrate in 50 cm water. Allow to stand for one hour, filter under suction, wash widi water and dry by continued suction while pressing between filter paper. Weigh your product and calculate the % yield based on Zn. 

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