Cobalt , bromide

Water content No decanted water Non-detectable by cobalt bromide test (NF M 41-004) Pass valve freezing test (ASTM D 2713, ISO 13758)... 

Water in propane NFM 41-004 Change in color of cobalt bromide... 

Catalysts other than the above cobalt salts have been considered. Several patents suggest that cobalt bromide gives improved yields and faster reaction rates (12—16). The bromide salts are, however, very corrosive and require that expensive materials of constmction, such as HastaHoy C or titanium, be used in the reaction system. Only one faciHty, located in the UK, is beHeved to uti1i2e cobalt bromide catalyst in the production of ben2oic acid. 

The effects of manganese on the cobalt/bromide-catalyzed autoxidation of alkylaromatics are summarized in Figure 17. The use of the Mn/Co/Br system allows for higher reaction temperatures and lower catalyst concentrations than the bromide-free processes. The only disavantage is the corrosive nature of the bromide-containing system which necessitates the use of titanium-lined reactors. 

Acetylene compounds Dicobaltoctacarbonyl Formation of colored complexes. After the reagent excess has been washed out, reaction with bromine vapor yields cobalt bromide, which reacts with a-nitroso-P-naphthol to yield red chromatogram zones on an almost colorless background. [11]... 

Two general approaches have been used to prepare the cobalt powders. The first method(34,37,42) used 2.3 equivalents of lithium along with naphthalene as an electron carrier in DME to reduce anhydrous cobalt chloride to a dark gray powder, L Use of cobalt bromides or iodides gave a... 

Cobalt bromide is used as a catalyst in the technology of production of arylcarboxylic acids by the oxidation of methylaromatic hydrocarbons (toluene, p-xylene, o-xylene, polymethyl-benzenes). A cobalt bromide catalyst is a mixture of cobaltous and bromide salts in the presence of which hydrocarbons are oxidized with dioxygen. Acetic acid or a mixture of carboxylic acids serves as the solvent. The catalyst was discovered as early as in the 1950s, and the mechanism of catalysis was studied by many researchers [195-214],... 

These reactions result in an additional route of chain propagation, which allows one to exceed the rate limit due to the mechanism of action of only variable-valence ions. In fact, the initial rate of RH transformation in the presence of the cobalt bromide catalyst is determined by the rate of two reactions, namely, R02 with RH (kp) and R02 with Co2+ (kp), followed by the reactions of Co3+ with Br and Br with RH. The general scheme proposed by Zakharov includes the following steps (written in the simplified form) [206] ... 

Generalizing the known data and established experimental peculiarities of the action of the cobalt bromide catalyst, we have to emphasize the following advantages of cobalt bromide catalysis ... 

In a series of investigations [140-146], Gomes etal. utilized cobaltous bromide (although some work was done with cobaltous chloride) as a precursor for the catalytic reduction of aryl halides in the presence of activated olefins to afford... 

Further, the frans-series of salts has never been found to give isomers, as they are symmetrica], and therefore such isomerism should not exist. 1-bromo-C-ammino-diethylcnediamino-cobaltic bromide therefore exists in only one form, and the configuration is given by... 

Cobaltous bromide and cobaltous iodide in the solid state absorb ammonia with formation of hexammino-cobaltous bromide, [Co(NH3)6]Br2, and hexammino - cobaltous iodide, [Co(NH3)6]I2, respectively. The compounds are unstable, and rapidly lose ammonia on heating and decompose on solution in water. Tetrammino-cobaltous iodide, [Co(NH3)4]I2, is also known. It may be prepared by treating a concentrated solution of cobaltous iodide with ammonia a pale red precipitate is formed, which gradually dissolves on warming, giving a violet-coloured liquid from which small rose-red crystals of the tetram-mine separate. It also is unstable, and decomposes on heating or on standing in air with loss of ammonia and formation of cobalt oxide. In aqueous solution it turns brown, ammonia is evolved, and a precipitate of cobaltous oxyiodide separates. 

Hexammino-cobaltic Bromide, [Co(NH3)6]Br3, is obtained from the chloride by precipitating the solution with aqueous potassium bromide, or better, by saturating a solution of hexammino-cobaltic hydroxide with hydrogen bromide. The precipitate formed is recrystallised from water and obtained in glistening rhombic plates. 

If heated in neutral solution it is completely decomposed. Aquo-pentammino-cobaltic bromide, [Co(NH3)5H20]Br3, and aquo-pent-ammino-cobaltic iodide, [Co(NH3)5H20]I3, are prepared by similar means. 

The chloride, [Co en2(H20)2]Cl3 or [Co eii2(H20)2]Cl3.2H20, is prepared from trans-hydroxo-aquo-cobaltic bromide, [Co ena(HaO)... 

Chloro-pentammino-cobaltic Bromide, [Co(NH3)5Cl]Bra, may be prepared from the chloride by treating a solution, which has been made slightly acid with dilute sulphuric acid, with well-cooled hydro-bromic acid. The precipitate formed is washed with dilute aqueous hydrogen bromide and then with alcohol. It may be formed also from the corresponding chloro-carbonate by precipitating from solution with concentrated hydrobromic acid. It crystallises in red oetahedra, and is more easily soluble than the chloride. 

Ethylenediamino-derivatives of the series are known for example, chloro-ammino-diethylenediamino-cobaltic nitrate, [Co(NHs) (en)2Cl](X03)2 chloro - ammino - diethylenediamino - cobaltic chloride, [Co(XH8)(en)2Cl]Cl2 and bromo-ammino-diethylenediamino -cobaltic bromide, [Co(NH 3) (en)2Br]Br2. 

They are isomeric with chloro-nitro-tetrammino-cobaltic chloride, [Co(NH3)4(N02)C1]C1.H20, and bromo - nitro - tetrammino - cobaltic bromide, [Co(NH3)4(N02)Br]Br.H20, the substances originally described by Jorgensen as aquo-salts. These salts are red, whereas all the aquo-nitro-salts are yellow in colour. Both salts are easily transformed into the isomeric nitro-halogeno-compounds on treatment with water.3... 

Bromo-aquo-tetrammino-cobalticBromide,[Co(NH3)4H2O.Br] Br , may be prepared by warming dibromo-tetrammino-cobaltic bromide, [Co(NII3)4Br2]Br, with water and a little hydrobromie acid. It crystallises in brownish-violet prisms.3... 

A solution of chloro-diaquo-triammino-cobaltic bromide is blue in colour, and on the addition of hydrobromie acid the isomeric chloro-bromo-aquo-triammino-eobaltic bromide monohydrate, [Co(NH3) 3(H 20) ClBr]Br.H20, separates in brown needles even at temperatures below... 

The Sulphato-pentammino-cobaltic Salts, [Co(NH3)s(S04)JR, are isomeric with the acido-pentammino-sulphate series thus, sulphato-pentammino-cobaltic bromide, [Co(NHs)B(S04)]Br, and bromo-pent-ammino-cobaltic sulphate, [Co(NH3)5Br]S04, are isomeric, as also are [Co(NH3)5(S04)]C1 and [Co(NH3)5C1]S04 (see p. 130). 

Sulphato-pentammino-cobaltic Bromide, [Co(NH3)5S04]Br, is prepared from chloro-pentammino-chloride by transforming it by means of concentrated sulphuric acid. The following reaction takes place... 

Dibromo-tetrammino-cobaltic Bromide, [Co(NH3)4Bra] Br, is prepared from carbonato-tetrammino-eobaltic bromide by acting upon it with fuming hydrobromic acid, when the following reaction takes place —... 

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