Cobalt stearate

Cobalt salts such as cobalt stearate are commonly used as rubber compound additives to supplement the HRH components for better rubber-to-brass-plated steel tire cord adhesion. 

Cobalt stearate is produced from stearic acid (usually from beef tallow) and cobalt (from cobalt ore), which are both discussed in Chapter 2. 

Cobalt stearate (or other cobalt salts) is sometimes used as rubber compounding ingredients to improve rubber-to-brass steel tire cord adhesion under certain circumstances. Commonly, a careful use of cobalt soap such as cobalt stearate may actually improve certain adhesion characteristics if it is used properly. Since rubber-substrate adhesion is a variable phenomenon, many technologists feel that the contribution of cobalt is to improve the reliability of the adhesion rather than the adhesion per se. Over the past three decades, this reliability of adhesion has been found to be of much importance in the manufacture of steel-wlre-reinforced tires and other rubber products. Thus the end result is a greater consistency of product quality, with fewer production rejects and subsequent failures in actual service. 

Cobalt soaps are still used in the coatings industry as driers for alkyd or oil-based paints in order to promote oxidative film hardening. 

certain cobalt salts are used in the plastics industry under carefully controlled conditions as promoters to accelerate the decomposition of peroxides to cure unsaturated polyester resins in molding and casting. 

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Courtesy of Synthetic Organic Chemicals, U.S. Production and Sales, U.S. International Trade Commission. Less than 100 t of cadmium stearates produced ia all years except 1986 for which production was 350 t. Also 160 t cobalt stearates. 

The first term on the right-hand side denotes the rate of dioxygen reaction with styrene (see Chapter 4) and the second term is the rate of catalytic free radical generation via the reaction of styrene with dioxygen catalyzed by cobaltous stearate or cobaltous acetylacetonate. The rate constants were found to be ki = 7.45 x 10-6 L mol-1 s-1, k2 = 6.30 x 10 2 L2 mol 2 s 1 (cobaltous acetylacetonate), and k2 = 0.31L2 mol-2 s 2 (cobaltous stearate) (T = 388 K, solvent = PhCl [169]). The mechanism with intermediate complex formation was proposed. 

Cobalt stearate, salicylate and acetyl acetonate etc. Promising platonizers and catalysts for DB Propellants [247]. 

Et2AlCl could be replaced by the sesquichloride or by a mixture of a trialkylaluminum and a reactive halide such as benzyl chloride or tert-butyl chloride. The effective cobalt compounds were those which are known to yield cis-1,4-polybutadiene—e.g. cobalt stearate, cobalt acetyl-acetonate, cobalt bis(salicylaldehyde imine), cobalt chloride-pyridine, etc. Et2AlCl concentration could be varied within the range 0.3-5% by weight based on PVC, and the cobalt compound concentration was 0.002-0.01 mole per mole of Et2AlCl. 

A convenient method for carrying out the reaction of a high cis-1,4-polybutadiene with PVC was to polymerize butadiene using a suitable catalyst system—e.g., Et2AlCl-cobalt stearate-terf-butyl chloride or Et3Al-cobalt chelate-benzyl chloride, and then to add an appropriate quantity of the resultant polybutadiene solution to a suspension of PVC in chlorobenzene. Additional Et2AlCl could then be added to the reaction mixture, although this was unnecessary if the initial concentration was adequate. 

Many authors128, 142-146 have proposed reaction (112), or a variant of it, in an attempt to explain kinetic data. For example, Uri145 proposed the following mechanism for the initiation of cobaltous stearate-catalyzed autoxidation of methyl linoleate in benzene ... 

In the autoxidation of neat hydrocarbons, catalyst deactivation is often due to the formation of insoluble salts of the catalyst with certain carboxylic acids that are formed as secondary products. For example, in the cobalt stearate-catalyzed oxidation of cyclohexane, an insoluble precipitate of cobalt adipate is formed. 18fl c Separation of the rates of oxidation into macroscopic stages is not usually observed in acetic acid, which is a better solvent for metal complexes. Furthermore, carboxylate ligands may be destroyed by oxidative decarboxylation or by reaction with alkyl hydroperoxides. The result is often a precipitation of the catalyst as insoluble hydroxides or oxides. The latter are neutralized by acetic acid and the reactions remain homogeneous. 

Thus in the system cobaltous stearate-linoleic acid cobaltic stearate is formed in situ and becomes a very efficient catalyst (13), Both the absolute and the relative rates of the above-mentioned hydroperoxide and substrate reactions depend on the nature of the substrate. With linoleic acid at a concentration ratio of [RH]/[ROOH] of about 50, the reaction with the substrate predominated over the one with the hydroperoxide. 

An independent method (279) involves passing oxygen through a solution of vincadifformine (76) in the presence of metal salts (e.g., copper sulfate, ferric chloride, or cobalt stearate) in aqueous hydrochloric acid at 50°C for 8 days vincamine (286) is thus obtained in 20% yield and 16-epivincamine in 15% yield. Again, tabersonine gave similar results. 

One can see that the most popular zinc stearate decreases the lifetime of the HDPE by more than three times, copper stearate by 12.5 times, and cobalt stearate by 25 times. 

The most popular cationic catalysts are soluble Co " and Cr " salts and mixtures thereof Examples of such salts that are added to catalyze the oxidation are cobalt stearate and cobalt naphthenates. Applied concentrations of these transition metals range from more than 10 ppm down to sub-ppm levels. These catalysts also catalyze the decomposition of CHHP, reducing the residual concentrations of CHHP. Nevertheless, both for economic and safety reasons, the residual CHHP is decomposed to mainly cyclohexanone and cyclohexanol. This reaction is carried out in an after-reactor either in a monophasic system in cyclohexane or in a biphasic system with an aqueous caustic solution as second phase. 

The oxidative rearrangement of vincadilformine (211) to vincamine (231) (whose structure is shown in Scheme 26) can be done directly and in approximately 30% yield, by the use of oxygen in the presence of metal salts e.g. copper sulphate, ferric chloride, or cobalt stearate) and dilute hydrochloric acid some 16-epi-vincamine is naturally also obtained. Tabersonine likewise gives 14,15-dehydrovincamine and its 16-epimer." This method avoids the undesired... 

An alternative method is to use a semi-coitinuous process in which inverse emulsion and initiator solution are progressively added in the course of the reaction. When redox initiators operating at room temperature are used, a common practice is first to inject the oxidant part in the water-in-oil emulsion and to add the reducing portion progressively [11]. This initiation mode is an additional way to control the polymerization reaction since the half-life of a redox initiator is shorter than that of an azo initiator 10 h at 64 °C for AIBN (2,2 -azobis(isobutyrtHiitrile)) compared to 8 min at 45 °C for /-butyl hydroperoxide/cobalt stearate pair [16]. 

Heaton, F.W. and Uri, N. The aerobic oxidation of unsaturated fatty acids and their esters cobalt stearate-catalyzed oxidation of hnoleic acid. J. Lipid Res. 2, 152-160 (1961). 

Hiatt, Irwin and Gould [328] studied the decomposition of terU mXyX hydroperoxide in the presence of cobaltous and cobaltic stearates (St), octanoates (Oct) and acetylacetonates as well as iron phthalocyanine. They found that the acetylacetonates of Ni(II), Co(III) and Fe(III) were inert toward terUh xiyX hydroperoxide at room temperature. In chlorobenzene or alkanes at 25-45 °C, half lives for decomposition of O.IM ferf-butyl hydroperoxide by 10 M catalyst ranged from 1-10 min with the active catalysts. Products included approximately 88% tert-huXyX alcohol, 11% di-rer -butyl peroxide, 1% acetone and 93% O2. These authors reported that in general, the choice of metal ion, as long as it can undergo a facile one-electron redox reaction, had little effect on products or reaction rates [328]. 

Razumovskii SD, Zaikov GY (1982) Effect of ozone on saturated polymers. Polymer Sci USSR 24(10) 2305-2325 Roy PK, Surekha P, Rajagopal C, Chatterjee SN, Choudhary V (2005) Effect of benzil and cobalt stearate on the aging of low density polyethylene films. Polym Degrad Stabil 90(3) 577-585 Scott G (1981) Mechanism of polymer stabilization. In Scott G (ed) Developments in polymer stabilization, 4th edn. Applied Science, London, pp 276-289... 

FIGU RE 6.4 Kinetics of oxygen consumption of polyethylene containing 10 to 10 mol/mol PE of cobalt stearate (1), cobalt chloride (2), cobalt oxide C03O4 (3), cobalt sulfate C0SO4 (4), metallic cobalt (5), and PE without filler (6). 

Bicyclo[5,3,0]dec-l(7)-en-2-one was obtained by anodic oxidation of bicyclo-[4,4,0]decane-l,6-diol in methanol containing tetraethylammonium p-toluenesul-phonate. The dicarboxylic acid (68), used in the synthesis of methymycin, was obtained by oxidative cleavage of 8-formylbicyclo[4,2,l]nona-2,4-dien-7-one. Autooxidation of (-t-)-car-3-ene in the presence or absence of cobalt stearate gave a complex mixture of products including eucarvone (up to 11.5 %) and 3,6,6-trimethylcyclohepta-2,4-dienone (up to 48 %). 3-Methylene-4-cholestene gave a 40% yield of 3,3-diazido-A-homochoIest-5-ene when treated with Pb(OAc)4 (N3) . ... 

Li et al. also reported the colloidal synthesis of Co-doped CdSe nanowires by the SLS strategy using the same reactants, except (MnSt)2 was replaced by cobalt stearate (CoSt)2 and the injection temperature was increased to 280°C. As-grown Co Cdi. Se (x = 0.3%) NWs were of 17.7 1.9nm in diameter and 1.8 0.2 pm in length with Bi catalysts located on both NW ends which demonstrated the SLS growth mechanism. The admixture of zinc blende and wurtzite structures were observed from TEM images. The diameter of the NWs can be tailored between 8 to 30 nm and the Co concentration can be tuned from 0 to 2.1% by varying the concentration of the reactants and reaction temperature. The temperature-dependent emission spectra of the Co-doped CdSe NWs were blue-shifted with increase of... 

The relative catalytic activities of a series of cobaloximes and of aquo-cobalamine for homogeneous oxidation of formaldehyde have been qualitatively assessed. Vitamin Biaa is by far the most effective the rate law for the process is complicated. The effect of these catalysts on decomposition of the formic acid produced was also studied. Somewhat simpler cobalt complexes catalyse the oxidation of alkylbenzenes. Thus cobalt(ii) acetate in hydrochloric acid is a good catalyst for the oxidation of p-xylene or p-toluic acid to terephthalic acid. Co(acac>3 catalyses oxidation of toluene, and a cobalt stearate complex catalyses the oxidation of isopropylbenzene. ... 

Cobalt is important to the rubber industry to promote rubber-to-metal adhesion. The use of cobalt salts, such as cobalt stearate or cobalt naphthenate as compounding additives, will promote better adhesion between cured rubber and brass-coated steel tire cord. 

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