Cobalt acetylacetonate catalyst

Figure 2. Visible light spectra of cobalt acetylacetonate catalysts in benzene...

The liquid-phase oxidation of acrolein (AL), the reaction products, their routes of formation, reaction in the absence or presence of catalysts such as acetylacetonates (acac) and naphthenates (nap) of transition metals and the influence of reaction factors were discussed in an earlier paper (22). The coordinating state of cobalt acetylacetonate in the earlier stage of the reaction depends on the method of addition to the reaction system (25, 26). The catalyst, Co(acac)2-H20-acrolein, which was synthesized by mixing a solution of Co(acac)2 in benzene with a saturated aqueous solution, decreases the induction period of oxygen uptake and increases the rate of oxygen absorption. The acrolein of the catalyst coordinated with its cobalt through the lone pair of electrons of the aldehyde oxygen. Therefore, it is believed that the coordination of acrolein with a catalyst is necessary to initiate the oxidation reaction (10). 

Visible light spectra were obtained using a Hitachi Model EPI-2 spectrometer. The absorption spectra of a reaction mixture formed, when cobaltous or cobaltic acetylacetonate was used as a catalyst, were measured to detect the state of the catalyst quantitatively. The spectrum of the reaction solution had a maximum absorption at 500 to 600m//, and a strong absorption in the ultraviolet region. The concentration of the catalyst in the oxidation solution was suitable for measuring the absorption spectra. The variation of the spectra with time was measured during the oxidation. 

The polymerization of butadiene to 1.2 polymers with anionic Ziegler type catalysts has been studied by Natta and co-workers (46). They have shown that isotactic 1.2-polybutadiene can be produced by the use of catalysts which are made up of components which have basic oxygen and nitrogen structures such as triethylaluminum with cobalt acetylacetonate or with chromium acetylacetonate. Natta and co-workers have shown that either syndiotactic or isotactic structures are produced depending on the ratio of aluminum to chromium. Syndiotactic structures are obtained at low aluminum to chromium ratios while isotactic polybutadiene is obtained at high ratios. The basic catalyst component is characteristic of syndiotactic catalysts. Natta, Porri, Zanini and Fiore (47) have also produced 1.2 polybutadiene using... 

The anionic nickel acetylacetonate catalyst gives only the cis, cis, trans product. Intermediate catalysts have already been seen to give cis, cis, cis structures which do not terminate but produce cis polybutadiene. This will also be seen later with cobalt iodide. At high temperatures or with strongly cationic systems the cyclic dodecatrienes are isomerized to the most stable trans, trans, trans structure. 

A set of three Co-doped precursors (with 1, 2 and 5 wt% Co) were prepared by dissolving the required amount of cobalt acetylacetonate in isobutanol prior to the operation of refluxing with isobutanol and 85% H3PO4. The subsequent filtration, washing and doping procedures were identical to that employed for the undoped precursor. These doped catalysts were then activated for 25h at 400°C under the same reaction mixture and flow conditions as described previously. 

Another supporting evidence for complex formation as a prerequisite to synergism was obtained from the study of the catalysis of phenyl isocyanate-butanol reaction by soluble organic cobalt compounds in presence and absence of DABCO catalyst. The results obtained are presented in Figures 4 and 5. It is evident that the combination of DABCO catalyst with divalent cobalt compounds shows synergistic effects while the trivalent cobalt acetylacetonate shows relatively low activity. The explanation of these observations is the structure of these compounds. 

The reduction of cobalt acetylacetonate with triakylaluminium leads to species composed of zerovalent cobalt and unreduced cobalt species. The exact composition depends upon the Al/Co ratio and the activation process. When we used a catalyst corresponding to a Al/Co = 1, activaded with hydrogen at 180°C, we obtained an increase of the selectivity of the hydrogenation of 2-pentyl-2-nonenal into 2-pentyl-2-nonenol. 

The catalysts were prepared by reducing the cobalt acetylacetonate dissolved in benzene, under a inert atmosphere of argon, using a known quantity of triethylaluminium (as a function of the desired Al/Co ratio). The solution immediatly became black and the metallic particles formed were able to be stabilized by butadiene at 0°C. The solvent employed during the hydrogenation reaction was dodecane or propylene carbonate. The benzene was then evaporated under a controlled atmosphere and the degradation products were then removed and analyzed, the temperature being increased up to 200°C. The catalyst thus obtained was used "in situ". 

For AI/Co of O.S the Co(acac)2 species are always present in the mechum. However during the treatment by hydrogen at high temperature they transform preferably into alkoxide species. The species of the catalyst are then composed of reduced and unreduced cobalt in equal quantities If the amount of reductant is increased (Al/Co = l.S) the cobalt acetylacetonate is almost entirely reduced and the catalyst species are composed essentially of metallic cobalt. 

N,N,N, N -Tetramethyl-1,3-butanediamine Titanium acetylacetonate Triethylamine Zinc acetylacetonate catalyst, esterification Acetyl acetone Acetyl chloride Ammonium lactate Calcium acetate Cobalt diacetate Cumene sulfonic acid Ethylacetoacetate 2-Ethylhexyl titanate Fluoboric acid Lead acetate... 

Cinnamylsuccinic anhydride, MA-allylbenzene adduct, 148, 163 Citraconic anhydride, 30, 31 hydrolysis rate, 74 Claracin antibiotics, 100 Cobalt acetylacetonate, 289 Cobalt molybdate, butane oxidation catalyst, 34 Cobalt octoate, for polyester ambient curing, 488 Collagen, poly(styrene-alt-MA) grafted, 476 Colorimetric methods, MA detection, 7 7r-Complexes, 215, 235 Complexomer... 

In addition to rhodium(III) oxide, cobalt(II) acetylacetonate or dicobalt octacarbonyl has been used by the submitters as catalyst precursors for the hydroformylation of cyclohexene. The results are given in Table I. 

The activity of Ziegler-type systems such as M(acac) -AlEt3 (M = Cr, Mn, Fe, Co, or Ni acac = acetylacetonate) was examined with 1-olefins and triethyl- or triethoxysilanes (55). Systems with nickel or cobalt showed low activity for hydrosilation but isomerized the olefin and were reduced to the metal. The study was extended to dienes and acetylenes (56). Isoprene gave the same products with these catalysts as are made with chloroplatinic acid. Penta-1,3-diene with Pt gave l-methylbut-2-en-ylsilanes. The Ziegler catalysts gave mainly penta-2-enylsilanes... 

Ziegler-type catalysts obtained from an organic acid salt or acetylacetone salt of nickel, cobalt, iron, or chromium which reacts with a reducing agent such as an organic aluminum compound. 

Indium mediates a highly enantioselective Barbier-type allylation of both aromatic and aliphatic aldehydes, using a chiral ethanolamine auxiliary, readily recoverable by acid extraction.193 Barbier coupling of aldehydes can be carried out in water using tin(II) chloride, with cobalt(II) acetylacetonate as catalyst.194... 

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