Cobalt acetate halides

The higher iodides, however, tend to be unstable and decomposition occurs to the lower iodide (PI5 -> PI3). Anhydrous chlorides and bromides of some metals may also be prepared by the action of acetyl (ethanoyl) halide on the hydrated ethanoate (acetate) in benzene, for example cobalt(II) and nickel(II) chlorides ... 

The scope of this reaction is similar to that of 10-21. Though anhydrides are somewhat less reactive than acyl halides, they are often used to prepare carboxylic esters. Acids, Lewis acids, and bases are often used as catalysts—most often, pyridine. Catalysis by pyridine is of the nucleophilic type (see 10-9). 4-(A,A-Dimethylamino)pyridine is a better catalyst than pyridine and can be used in cases where pyridine fails. " Nonbasic catalysts are cobalt(II) chloride " and TaCls—Si02. " Formic anhydride is not a stable compound but esters of formic acid can be prepared by treating alcohols " or phenols " with acetic-formic anhydride. Cyclic anhydrides give monoesterified dicarboxylic acids, for example,... 

Cobalt(lll)(salen) catalyses the carboxylation of benzyl chlorides and allyl chlorides but not of halobenzenes [246], PdCl2(PPh3)2 catalyses the carboxylation of aryl halides, P-bromostyrene and allyl acetates [247]. 

The ammine complexes of Co3+ are prepared by adding excess ammonia to a solution of cobalt salt followed by air oxidation and boding. The brown solution turns pink on boiling. The cyanide complexes are made by adding excess potassium cyanide to a solution of cobalt salt. Acidification of the solution with a small amount of acetic or hydrochloric acid followed by boiling yields K3Co(CN)6. The aquo-halo mixed complexes are formed by stepwise substitution of H2O molecule with halide ion in the coordination sphere. In general, a mixed complex may be prepared by substitution with a specific anion. 

Ruthenium, cobalt and halogen are the key elements of this catalysis (2), although ruthenium in combination with halogen-containing zirconium and titanium derivatives is also effective (3). In the case of the Ru-Oo couple, the highest yields of acetic acid may generally be achieved with ruthenium oxide, carbonyls and complex derivatives in combination with various cobalt halides dispersed in low-melting quaternary phosphonium halide salts (2). 

Data in Table I illustrate the production of acetic acid from 1/1 syngas catalyzed by ruthenium-cobalt halide bimetallic combinations dispersed in tetrabutylphosphonium bromide (m.p. 100°C). 

Electroreduction of the cobalt(II) salt in a mixture of either dimethylform-amide-pyridine or acetonitrile-pyridine as solvent, often in the presence of bipyridine, produces a catalytically active cobalt(I) complex which is believed to be cobalt(I) bromide with attached bipyridine ligands (or pyridine moieties in the absence of bipyridine). As quickly as it is electrogenerated, the active catalyst reduces an aryl halide, after which the resulting aryl radical can undergo coupling with an acrylate ester [141], a different aryl halide (to form a biaryl compound) [142], an activated olefin [143], an allylic carbonate [144], an allylic acetate [144, 145], or a... 

When acido groups, halides, thiocyanate, azide, acetate, and nitrate are present in the coordination sphere of cobalt(III), they appear to be oxidized in preference to coordinated ammonia. Many of the radicals thus produced are capable of oxidizing ammonia released from the complex or of interfering in other ways with the reduction process, and these systems have proved very difficult to understand even in general terms. Quantum yield and other data for a number of acidopentammine and certain other complexes are given in Table IV the data on the aquation reactions of some of the complexes are considered in Section I1I-D. 

Rubidium metal alloys with the other alkali metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double halide salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and zinc. These complexes are generally water insoluble and not hygroscopic. The soluble rubidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide,... 

The oxidation of hydrocarbons by cobalt(lll) acetate has been thoroughly investigated, due to its relevance to industrial homolytic oxidation processes.56 361 547 Radical intermediates are produced from one-electron oxidation of hydrocarbons according to an electron transfer or an electrophilic substitution mechanism previously described in equations (200)-(203). These oxidations are dramatically accelerated by the presence of strong acids or halide salts. 

A Belgian patent (178) claims improved ethanol selectivity of over 62%, starting with methanol and synthesis gas and using a cobalt catalyst with a halide promoter and a tertiary phosphine. At 195°C, and initial carbon monoxide pressure of 7.1 MPa (70 atm) and hydrogen pressure of 7.1 MPa, methanol conversions of 30% were indicated, but the selectivity for acetic acid and methyl acetate, useful by-products from this reaction, was only 7%. Ruthenium and osmium catalysts (179,180) have also been employed for this reaction. The addition of a bicyclic trialkyl phosphine is claimed to increase methanol conversion from 24% to 89% (181). 

A very dangerous fire and moderate explosion hazard when exposed to heat or flame can react vigorously with oxidizing materials. Warning pyrophoric in air. Mixtures with nitrogen oxide explode above 50°C. Violent reaction with zinc + transition metal halides (e.g., cobalt halides, rhodium halides, ruthenium halides). Mixtures with acetic acid + water produce a pyrophoric powder. To fight fire, use water, foam, CO2, dr " chemical. See also CARBONYLS and IRON COMPOUNDS. 

Acyl halides can also be converted to carboxylic acids by using ethers instead of alcohols, in MeCN in the presence of certain catalysts such as cobalt(II) chloride. " A variation of this reaction has been reported that uses acetic... 

The yield of the arylcyclopropanes is very sensitive to the catalyst employed. Very low yields (< 10%) were observed when lithium salts were employed. Magnesium, cobalt and copper salts gave better results, but the best results were achieved with zinc halides and rho-dium(II) acetate. This was apparent when 7-phenylbicyclo[4.1. OJheptane (4) was prepared from cyclohexene and phenyldiazomethane. ... 

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