Cobalt chloride catalyst

Bis(trimethylsilyl) sulphide reacts with acyl silanes in the presence of a cobalt chloride catalyst to afford the corresponding thiocarbonyl derivatives, thioacyl silanes (Scheme 100)214. The reaction is mild and proceeds in good yields. It is also applicable to aldehydes. Thioacyl silanes have been prepared from the corresponding haloacyl silanes by reaction with hydrogen sulphide (vide supra, Section IV.A.3)196. 

In a study of the reaction of polybutyl vinyl ether with elemental sulfur in the presence of cobalt chloride catalyst, Morozova and co-workers [27] showed that the reaction involved dehydrogenation and step-by-step incorporation of sulfur into the polymer leading to polyacetylene and polythienothiophene structures. 

A typical Ziegler-Natta catalyst might be made from TiCl or TiCl and Al(C2H )3. Vanadium and cobalt chlorides are also used, as is A1(C2H3)2C1. When these substances are mixed in an inert solvent, a crystalline soHd is obtained. Early catalysts consisted of the finely divided soHd alone, but in modern catalysts, it is often supported on Si02 or MgCl2. 

As with polybut-l-ene and many other vinyl monomers that contain an asymmetric carbon, isotactic, syndiotactic and atactic stmctures may be drawn. Using co-ordination catalysts such as mixtures of cobalt chlorides, aluminium alkyls, pyridine and water high-1,2 (high vinyl) polymers may be obtained. One product marketed by the Japan Synthetic Rubber Company (JSR 1,2 PBD) is 91% 1,2, and 51-66% of the 1,2 units are in the syndiotactic state. The molecular mass is said to be several hundred thousand and the ratio MJM is in the range 1.7-2.6. 

Nylon-6,6 (7.5 g), nylon-6 (7.5 g), and 0.25 g of Lewis acid catalysts such as zinc chloride, cobalt chloride, calcium chloride, and barium carbonate were charged... 

A cobalt-based catalyst, prepared by reducing Co(acac)3 with diethylalumi-num chloride in the presence of the bidentate ligand l,2-bis(triphenylphosphi-no)ethane, accelerates [87] the cycloadditions of norbornadiene (88) with a variety of acetylenes (Equation 3.30). 

It was shown that dibenzothiophene oxide 17 is inert to 1-benzyl-1,4-dihydro nicotinamide (BNAH) but that, in the presence of catalytic amounts of metalloporphyrin, 17 is reduced quantitatively by BNAH. From experimental results with different catalysts [meso-tetraphenylporphinato iron(III) chloride (TPPFeCI) being the best] and a series of substituted sulfoxides, Oae and coworkers suggest an initial SET from BNAH to Fe followed by a second SET from the catalyst to the sulfoxide. The results are also consistent with an initial coordination of the substrate to Fe , thus weakening the sulfur-oxygen bond in a way reminiscent of the reduction of sulfoxides with sodium borohydride in the presence of catalytic amounts of cobalt chloride . ... 

A N -Carbonyldipyrazole reacts with ketones such as acetone, methyl ethyl ketone, and cyclic ketones, as well as such aldehydes as acetaldehyde and benzaldehyde to give dipyrazolylalkanes, also in the presence of catalyst, for example cobalt chloride.[293,[3°3... 

The electrochemistry of cobalt-salen complexes in the presence of alkyl halides has been studied thoroughly.252,263-266 The reaction mechanism is similar to that for the nickel complexes, with the intermediate formation of an alkylcobalt(III) complex. Co -salen reacts with 1,8-diiodo-octane to afford an alkyl-bridged bis[Co" (salen)] complex.267 Electrosynthetic applications of the cobalt-salen catalyst are homo- and heterocoupling reactions with mixtures of alkylchlorides and bromides,268 conversion of benzal chloride to stilbene with the intermediate formation of l,2-dichloro-l,2-diphenylethane,269 reductive coupling of bromoalkanes with an activated alkenes,270 or carboxylation of benzylic and allylic chlorides by C02.271,272 Efficient electroreduc-tive dimerization of benzyl bromide to bibenzyl is catalyzed by the dicobalt complex (15).273 The proposed mechanism involves an intermediate bis[alkylcobalt(III)] complex. 

Borohydride reduction of NiCl2 in dimethylformamide or dimethyl-acetamide leads to very active catalysts, thought to be homogeneous, for hydrogenation of monoolefins, unsaturated fats, cyclic dienes to monoenes, and saturated aldehydes and ketones (165, 538, 539). Cobaltous chloride systems have also been used (540). 

As recently reported, cobalt-catalyzed addition of olefins to butadiene is probably an example of the addition of cobalt alkyls to butadiene (106). The catalyst was the type prepared by reaction of cobalt chloride with an aluminum alkyl in the presence of a diene. A bis-7r-allylcobalt derivative is probably formed. The unstable 7r-allylcobalt compounds probably decompose (reversibly) into cobalt hydride. The hydride would add to the olefin present to form a dialkyl, which could then add again to the diene. 

Other possible catalysts for the reaction of various alkyl bromides with allyhnagnesium hahdes in THF are cobaltbis(l,3-diphenylphosphino)propane complex (equation 70) or cobalt chloride in combination with a diamine (equation 71) °. Cyclization products can... 

Aryl- or heteroarylzinc species have been successfully synthesized from the corresponding aryl or heteroaryl bromides or chlorides in high yields, on the laboratory scale (10 mmoles of substrate). The use of cobalt as catalyst allowed the synthesis of organozinc reagents using the sacrificial anode process with a wide variety of solvents. 

Cobalt Ziegler catalysts were also used for the manufacture of 1.2-polybutadiene by Susa (48). He obtained syndiotactic 1.2-poIy-butadiene from catalysts of extremely high ratios of triethylaluminum to cobalt chloride-dipyridine complex. However, as the anionic character of the catalyst system was decreased by the introduction of diethylalumi-num chloride, the 1.2 syndiotactic polymer decreased and increasing... 

When either an alcohol or an amine function is present in the alkene, the possibility for lactone or lactam formation exists. Cobalt or rhodium catalysts convert 2,2-dimethyl-3-buten-l-ol to 2,3,3-trimethyl- y-butyrolactone, with minor amounts of the 8-lactone being formed (equation 51).2 In this case, isomerization of the double bond is not possible. The reaction of allyl alcohols catalyzed by cobalt or rhodium is carried out under reaction conditions that are severe, so isomerization to propanal occurs rapidly. Running the reaction in acetonitrile provides a 60% yield of lactone, while a rhodium carbonyl catalyst in the presence of an amine gives butane-1,4-diol in 60-70% (equation 52).8 A mild method of converting allyl and homoallyl alcohols to lactones utilizes the palladium chloride/copper chloride catalyst system (Table 6).79,82 83... 

The thermal stability of poly(vinyl chloride) is improved greatly by the in situ polymerization of butadiene or by reaction with preformed cis-1,4-polybutadiene using a diethyl-aluminum chloride-cobalt compound catalyst system. The improved thermal stability at 3-10% add-on is manifested by greatly reduced discoloration when the modified poly-(vinyl chloride) is compression molded at 200°C in air in the absence of a stabilizer, hydrogen chloride evolution at 180°C is retarded, and the temperature for the onset of HCl evolution and the peak decomposition temperature (DTA) increase, i.e. 260°-280°C and 290°-325° C, respectively, compared with 240°-260°C and 260°-280°C for the unmodified homopolymer, in the absence of stabilizer. The grafting reaction may be carried out on suspension, emulsion, or bulk polymerized poly(vinyl chloride) with little or no change in the glass transition temperature. 

ALET3-teff-BuTYL Chloride-Cobalt Compound Catalyst. PVC, 20 grams, was suspended in 190 ml chlorobenzene, and the resultant slurry was cooled to 5°C. The addition of 2 grams of butadiene was followed by the successive addition of 0.01 mmole of cobalt (II) bis(salicylaldehyde imine), 2 mmoles of terf-butyl chloride, and 2 mmoles of triethylalumi-num. The reaction mixture was stirred at 8°C for 60 minutes and poured into 1 liter of methanol. The vacuum-dried product weighed 21.9 grams, representing an add-on of 5.1%. 

The base (B) used was dicyclohexylethylamine. At the higher temperatures the isomeric products that one would expect from an isomerization of the acylcobalt carbonyls were formed (see Section II, A). Amines were also used in place of alcohols to give amides. Thus benzyl chloride reacted with carbon monoxide and aniline in tetrahydrofuran solution at 35° C in the presence of sodium cobalt carbonylate catalyst to give a 47% yield of phenylacetanilide. 

Urushibara Co catalysts can be prepared exactly in the same way as the corresponding Ni catalysts, using cobalt chloride hexahydrate instead of nickel chloride hexahydrate as starting material. Similarly as with Raney catalysts, Urushibara Co has been found to be more effective and selective than Urushibara Ni in the hydrogenation of nitriles, affording high yields of primary amines.105,106... 

Donors have been added to the cobalt catalysts used to polymerize butadiene (20). Cobalt chloride-pyridine complexes gave a soluble catalyst with AlEt2Cl which was effective for cis polymerization of butadiene, but at the low concentrations of pyridine employed (Al/Co/py = 1000/1/1 to 4), there was no effect on the polymer structure. However, it was observed that the molecular weight fell as the ratio of pyridine to cobalt was increased. Isopropyl ether in the cobalt octoate-methylaluminum sesquichloride catalyst had a similar effect, although at the highest ether concentrations (typical ratios employed were Al/Co/iPr20 = 160/1/3.5 to 8), a reduction in cis content and polymerization... 

Other Cobalt Compounds. Catalysts prepared from cobalt oleate, octoate, and acetyl acetonate have also been examined. The characteristics of the reactions were the same as with cobalt chloride and naphthenate. The results are shown in Table X. 

Attempts to isolate the complex which forms trans polymer have been made, but no pure compounds have yet been isolated. From cobalt chloride, solid or liquid products were obtained which have variable composition. (Co = 5.7-15%, A1 = 5.2-10.6%, Cl = 20.6-26.2%, N = 4.5%, and replaceable ethyl groups 1.2-16.9%). It seems probable that in certain of these products some of the amine cobalt chloride complex is present without coordinated AlEt2Cl. The corresponding products from cobalt octoate have all undergone decomposition to a greater or lesser extent during isolation, but by suitably protecting the catalyst with other donors such as ethers or nonpolymerizable dienes, it may be possible to isolate a stable product. 

Conjugated dienes can be reduced to monoolefins by treatment with hydrogen, hydrated cobalt chloride, potassium cyanide, potassium chloride, sodium hydroxide, and tetramethylammonium chloride or benzyltri-ethylammonium chloride as the phase-transfer catalyst. The hydridopen-tacyanocobaltate anion, HCo(CN)s3, is the probable metal catalyst (47-... 

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