Phenol, 2- -, cobalt

Phenol Cobalt loaded activated carbon 98% Phenol removal... 

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. 

The selectivity of the oxidation of 2,6-disubstituted phenols depends on the type of oxidizing agent. For example, with a series of cobalt-containing catalysts of the salcomine type, oxidation of 2,6-dimethylphenol produces three products the poly(phenylene oxide), the diphenoquinone, and... 

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

Of these dyes, Acid Yellow 151 (37) still has the greatest market among the yellows. As reported by USITC, production had increased to 1989 tons in 1985 from 706 tons in 1975. It is produced by coupling diazotized 2-amino-l-phenol-4-sulfonamide to acetoacetanilide followed by metallizing with cobalt to obtain a 1 2 cobalt complex. Acid Orange 24 (38), which is sulfanilic acid coupled to resorcinol to which diazotized mixed xyUdines have been coupled, is an unsymmetrical primary diasazo dye with a bihinctional coupling component. 

Ben2oic acid is almost exclusively manufactured by the cobalt cataly2ed Hquid-phase air oxidation of toluene [108-88-3]. Large-scale plants have been built for ben2oic acid to be used as an intermediate in the production of phenol (by Dow Chemical) and in the production of caprolactam (by Snia Viscosa) (6-11). 

The oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone, known as KA-od (ketone—alcohol, cyclohexanone—cyclohexanol cmde mixture), is used for most production (1). The earlier technology that used an oxidation catalyst such as cobalt naphthenate at 180—250°C at low conversions (2) has been improved. Cyclohexanol can be obtained through a boric acid-catalyzed cyclohexane oxidation at 140—180°C with up to 10% conversion (3). Unreacted cyclohexane is recycled and the product mixture is separated by vacuum distillation. The hydrogenation of phenol to a mixture of cyclohexanol and cyclohexanone is usually carried out at elevated temperatures and pressure ia either the Hquid (4) or ia the vapor phase (5) catalyzed by nickel. 

A route to phenol has been developed starting from cyclohexane, which is first oxidised to a mixture of cyclohexanol and cyclohexanone. In one process the oxidation is carried out in the liquid phase using cobalt naphthenate as catalyst. The cyclohexanone present may be converted to cyclohexanol, in this case the desired intermediate, by catalytic hydrogenation. The cyclohexanol is converted to phenol by a catalytic process using selenium or with palladium on charcoal. The hydrogen produced in this process may be used in the conversion of cyclohexanone to cyclohexanol. It also may be used in the conversion of benzene to cyclohexane in processes where benzene is used as the precursor of the cyclohexane. 

The most commonly used stabilizers are barium, cadmium, zinc, calcium and cobalt salts of stearic acid phosphorous acid esters epoxy compounds and phenol derivatives. Using stabilizers can improve the heat and UV light resistance of the polymer blends, but these are only two aspects. The processing temperature, time, and the blending equipment also have effects on the stability of the products. The same raw materials and compositions with different blending methods resulted in products with different heat stabilities. Therefore, a thorough search for the optimal processing conditions must be done in conjunction with a search for the best composition to get the best results. 

The principle cost determinant in typical hydrolytic or phenolic resolutions is the cobalt catalyst, despite the relatively low catalyst loadings used in most cases and the demonstrated recyclability with key substrates. From this standpoint, recently developed oligomeric (salen)Co complexes, discussed earlier in this chapter in the context of the hydrolytic desymmetrization of meso-epoxides (Scheme 7.16), offer significant advantages for kinetic resolutions of racemic terminal epoxides (Table 7.3) [29-31]. For the hydrolytic and phenolic kinetic resolutions, the oligo-... 

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,... 

Anipsitakis GP, DD Dionysiou, MA Gonzalez (2006) Cobalt-mediated activation of peroxymonosulfate and sulfate radical attack on phenolic compounds. Implications of chloride ions. Environ Sci Technol 40 1000-1007. 

Although coordination of the heterocyclic nitrogen does not occur, two cobalt(II) complexes of 3-hydroxy-5-hydroxymethyl-2-methyl-4-formylpyridine have been isolated with stereochemistry [Co(34-H)A] 2H2O (A = NO3, OAc) [173], For both complexes coordination is ONS (deprotonated phenolic oxygen), but magnetic or electronic spectral data are not included. 

The variety and extent of research devoted to ligands carrying both O- and N-donors is simply immense. The type of cobalt(III) systems extant include amino acids, amino alcohols, amino ethers, amino phosphates, amino phenolates, as well as amide and imine analogs of these. These are met as simple chelates or more elaborate polydentates. Here, we highlight a strictly limited selection of examples to illustrate the type of systems reported no attempt at exhaustive review has been made. 

Anionic complexes can easily be prepared by the sulfonation of the aromatic rings in the complexes. Sulfonated cobalt phthalocyanine intercalated in a layered double hydroxide host was a stable catalyst for the oxidation of thiols162,163 and phenol derivatives.164 It was concluded that the complex has been intercalated with the plane of the phthalocyanine ring perpendicular to the sheet of the host (edge-on orientation) (Fig. 7.2). 

Now the possible explanation for the greater degradation of phenol by the cerium doped copper crystals than those of either cobalt or manganese ions could... 

Compound 10 has also been used to quantify double Lewis acid activation by two cobalt (HI) ions [37]. In 12, the RNA analogue 2-hydroxypropyl-phenyl phosphate (HPPP) is coordinated to the dinu-clear cobalt site. It is well known that in this substrate the hydroxypropyl group is an efficient intramolecular nucleophile. Release of phenol by intramolecular cyclization is much faster than the reaction by nucleophilic attack of bridging oxide, as observed in 11. At pH >8, transesterification rate is linearly dependent on hydroxide concentration since OH" acts as an intermolecular base for the deprotonation of the hydroxypropyl group. The second order rate constant for the hydroxide-dependent cleavage is 4 x 105 times larger than the second-order rate constant for the hydroxide-dependent spontaneous transesterification of hy-droxypropyl-phenyl phosphate. 

Table VII lists three precursor complexes of the type tris(phenolato)cobalt(III) and four compounds containing only one coordinated phenolate (146, 152). In the cyclic voltammograms of [Com(LBu2)] and [Com(LBuMet)] three reversible, ligand-centered, one-electron oxidation waves are observed. On the time scale of a Cou-lometric experiment, only the monocations [Com(LBu2 )]+ and [Com(LBuMet )]+ are stable and were spectroscopically characterized. In contrast, [Conl( L,Bu2)(acac)]+ undergoes a reversible one-electron oxidation yielding the dication [Com(T/Bu2 )(acac)]2+, which is fairly stable in solution.

Although the preparative chemistry of (vinylketene)cobalt(I) complexes is relatively limited in the literature, the methods used include all the major procedures that have been more widely exploited in the analogous chromium and iron systems. There are many similarities between the intermediates involved in the synthesis of vinylketene complexes of iron, chromium, and cobalt, but as the metal is varied the complexes containing analogous ligands often exhibit significant differences in stability and reactivity (see Sections II and VI). Comparison of such species has often been an important aim of the research in this area. The (vinylketene)cobalt(I) complexes have also been shown to be synthetically useful precursors to a variety of naphthols, 2-furanones, ce-pyrones, phenols,6,22,95 >8, y-unsaturated esters,51 and furans.51,96a... 

These results led to the proposal of the following mechanism. Decomplex-ation of the central C2 fragment allows coordination of the alkyne (intermediate 119), which then inserts to form the metallacycle 120. Deinsertion (reductive eliminate of the cobalt moiety allows ring closure to give the cyclohexadienone complex 121, which upon decomplexation yields the desired phenol. The regiochemistry of the alkyne insertion determines the ratio of 116 117 (for simplicity, only the sequence leading to 116 has been shown). 

Other routes. Alternate process technologies for making phenol avoid the cumene route. A few plants have used toluene as a feed, oxidizing it over a cobalt catalyst to give benzoic acid. That is followed by a reduction (removal of oxygen atom) to give phenol and carbon dioxide. 

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