Cobalt 3 3+ hydrolysis

Initially, the aqueous impregnation routes were beset with problems due to cobalt hydrolysis reactions that were amplified by the presence of the support material. The rate and extent of these reactions was highly dependent on, for instance, cobalt source, metal concentration, temperature and time. However, after much work, the chemistry was understood well enough to allow aqueous solutions to be used for impregnation. The ultimate performance of catalysts in the FT reaction (activity, selectivity and stability) could be directly related to the structure of the catalyst precursors. Detailed recipes were required to ensure that the correct precursors were made during the impregnation and subsequent calcination steps. 

It was first described in 1608 when it was sublimed out of gum benzoin. It also occurs in many other natural resins. Benzoic acid is manufactured by the air oxidation of toluene in the liquid phase at 150°C and 4-6 atm. in the presence of a cobalt catalyst by the partial decarboxylation of phthalic anhydride in either the liquid or vapour phase in the presence of water by the hydrolysis of benzotrichloride (from the chlorination of toluene) in the presence of zinc chloride at 100°C. 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

High purity acetaldehyde is desirable for oxidation. The aldehyde is diluted with solvent to moderate oxidation and to permit safer operation. In the hquid take-off process, acetaldehyde is maintained at 30—40 wt % and when a vapor product is taken, no more than 6 wt % aldehyde is in the reactor solvent. A considerable recycle stream is returned to the oxidation reactor to increase selectivity. Recycle air, chiefly nitrogen, is added to the air introducted to the reactor at 4000—4500 times the reactor volume per hour. The customary catalyst is a mixture of three parts copper acetate to one part cobalt acetate by weight. Either salt alone is less effective than the mixture. Copper acetate may be as high as 2 wt % in the reaction solvent, but cobalt acetate ought not rise above 0.5 wt %. The reaction is carried out at 45—60°C under 100—300 kPa (15—44 psi). The reaction solvent is far above the boiling point of acetaldehyde, but the reaction is so fast that Httle escapes unoxidized. This temperature helps oxygen absorption, reduces acetaldehyde losses, and inhibits anhydride hydrolysis. 

Cobalt difluoride [10026-17-2] C0F2, is a pink solid having a magnetic moment of 4, 266 x 10 J/T (4.6 Bohr magneton) (1) and closely resembling the ferrous (Fep2) compounds. Physical properties are Hsted in Table 1. Cobalt(II) fluoride is highly stable. No decomposition or hydrolysis has been observed in samples stored in plastic containers for over three years. 

The three chemical reactions in the toluene—benzoic acid process are oxidation of toluene to form benzoic acid, oxidation of benzoic acid to form phenyl benzoate, and hydrolysis of phenyl benzoate to form phenol. A typical process consists of two continuous steps (13,14). In the first step, the oxidation of toluene to benzoic acid is achieved with air and cobalt salt catalyst at a temperature between 121 and 177°C. The reactor is operated at 206 kPa gauge (2.1 kg/cm g uge) and the catalyst concentration is between 0.1 and 0.3%. The reactor effluent is distilled and the purified benzoic acid is collected. The overall yield of this process is beheved to be about 68 mol % of toluene. 

Alternative means for removal of carbonyl sulfide for gas streams iavolve hydrogenation. For example, the Beavon process for removal of sulfur compounds remaining ia Claus unit tail gases iavolves hydrolysis and hydrogenation over cobalt molybdate catalyst resulting ia the conversion of carbonyl sulfide, carbon disulfide, and other sulfur compounds to hydrogen sulfide (25). 

The TCBOC group is stable to the alkaline hydrolysis of methyl esters and to the acidic hydrolysis of r-butyl esters. It is rapidly cleaved by the supemucleophile lithium cobalt(I)phthalocyanine, by zinc in acetic acid, and by cobalt phthalocy-anine (0.1 eq., NaBH4, EtOH, 77-90% yield). 

Physical techniques can be used to investigate first order reactions because the absolute concentrations of the reactants or products are not required. Dixon et. al [3] studied the base hydrolysis of cobalt complex, [Co(NH3)5L]3+, where L = (CH3)2SO, (NH2)2C = O, (CH3)03P = O in glycine buffers. 

The release of dimethyl sulfoxide is accompanied by an increase in absorbance (D) at 325 nm. The absorbance D is defined as log(I(/I), where 1 and I are die intensities of die incident and transmitted light, respectively. Figure 3-15 illustrates die relationship between concentration and absorbance changes for die hydrolysis of die cobalt... 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

Delmas and his co-workers have done extensive work on pyroaurite-type materials which has recently been reviewed [73], In addition to precipitation methods, they have prepared the materials by mild oxidative hydrolysis of nickelates that were prepared by thermal methods similar to those used for the preparation of LiNiOz [74]. A cobalt-substituted material NaCoA ( Ni( A02) was prepared by the reaction of Na20, Co304 and NiO at 800 °C under a stream of oxygen. The material was then treated with a 10 molL-1 NaCIO +4 molL 1 KOH solution for 15h to form the oxidized y -oxyhydroxide. The pyroau-... 

Copper and cobalt catalyze the direct CHZ hydrolysis reaction at temperatures below 275 °F (135 °C), as shown ... 

Cobalt, dichlorobis(AvY -dimethyl-1,2-ethanediamine)-chloride hydrate isomerization, 1, 468 Cobalt, dich orobis(l,2-ethanediamine)-base hydrolysis, 1, 304 chloride anation, 1, 469 halogen exchange, 1, 468 chloride hydrate isomerization, 1, 468 isomers, 1,191 nitrate... 

First, consider the base hydrolysis of pentaammine(bromo)cobalt(2+) ion, Eq. (I -27).4 The rate is directly proportional to the hydroxide ion concentration,... 

Then we discovered that the addition of 2% of a cobalt salt to pellets of sodium borohydride caused rapid hydrolysis with liberation of hydrogen. 

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