Oxidation and Concentration

Significant attention is paid during both the reaction and the concentration to prevent ignition or explosion of the cumene-air mixtures. Furthermore, provisions are needed for a water or a steam quench to the concentrators to prevent hydroperoxide decomposition in case of an emergency. 

Cumyl hydroperoxide is eventually cleaved in the presence of an acid catalyst, to yield phenol and acetone, together with minor amounts of by-products such as a-methylstyrene, arising from dehydration of 2-phenyl-2-propanol, and dicumyl peroxide. a-Methylstyrene can be recovered to cumene in a hydrogenation stage. 

As the catalyst, concentrated (98%) sulfuric acid is almost exclusively used in the industrial practice. The cleavage is run in the presence of 0.2-1% of acid, under reduced pressure, at the boiling temperature of the cumyl hydroperoxide-acetone mixture, which depends on the acetone content. Again, the reaction is strongly exothermic ( 250 kj mol ) and the heat is removed by evaporation of acetone from the reaction mixture. At 70-80 °C, cumyl hydroperoxide conversion is virtually quantitative, with a selectivity to phenol up to 94-95%. 

Acetone and phenol can be recovered after the neutralization of the acidic mixture from the cleavage reactor with sodium hydroxide or phenolate solution. The neutralized mixture is then subjected to a series of distillations. Acetone is first distilled, then cumene is recovered, together with a-methylstyrene, which is either purified and marketed or hydrogenated back to cumene and recycled to the oxidation. Phenol is finally distilled with a purity up to 99.99%, suitable for the production of polycarbonate grade bisphenol A and other chemicals and polymers. 

The material balances of the oxidation/cleavage section and of the overall process are reported in Tables 13.2 and 13.3, respectively. Again, raw material consumption 

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If a chloride is heated with manganese(IV) oxide and concentrated sulphuric acid, chlorine is evolved. 

Ando, Shinada Hiraoka (1974) examined cements formed by the reaction between magnesium oxide and concentrated aqueous solutions of aluminium dihydrogen phosphate. Later, Finch Sharp (1989) made a detailed examination of the cement-forming reaction and reported that the reaction yielded cements of moderate strength. 

The reaction between arsenious oxide and concentrated nitric acid yields a mixture of nitric oxide and nitrogen dioxide. It also contains some nitrogen tetroxidc and perhaps trioxide, the amount in equilibrium depending upon the temperature of the gas. The compressed air forced in via flask A insures an excess of oxygen, and thus complete oxidation. Only a slow stream is necessary, two to three bubbles per second. 

Cobalt is capable of substitution for Fe2+ and other transition metals in the phyllosilicates due to the similarity of ionic radii. On the other hand, cobalt (Co2+) is specifically adsorbed by Mn and Fe oxides, and concentrations of Co sorbed by Mn oxides are much greater than those by Fe oxides (Backes, et al., 1995). Traina and Donor (1985) suggested that the Mn release during Co2+ ion sorption resulted not only from the oxidation of... 

Strong acids Attacked by oxidizing and concentrated acids ... 

Isoquinoline can be hydrogenated in high yield to 5,6,7,8-tetrahydroisoquinoline (47) by use of platinum oxide and concentrated hydrochloric acid at 50 psi (Scheme 33). The method employs a relatively large amount of catalyst (1 g of Pt02 for 8.6 g of isoquinoline) (75JOC2729). 

Oxidation and concentration (1) Cumene is oxidized to cumene hydroperoxide (CHP). A small amount of dimethylphenylcarbinol (DMPC) is also formed, but low-pressure and low-temperature oxidation results in very high selectivity of CHP. CHP is then concentrated and unreacted cumene is recycled back to the oxidation section. 

The sodium salt of the acid is obtained when sodium acetate, mercuric oxide, and concentrated alkali are heated together at 110° to 120° C. for two to three hours and the melt extracted with water. The residue remaining is a polymer of the preceding compound, and is insoluble in... 

The water is taken up by the sulfuric acid. Antimony and bismuth trifluorides are formed from the corresponding oxide and concentrated aqueous... 

Table 1. List of (Sn)MCM-41 catalysts with the concentration of Sn, adamantanone conversions achieved in Baeyer-Villiger oxidation and concentration of Lewis sites.

CHEMICAL PROPERTIES relatively stable in the absence of moisture at ordinary temperatures will not polymerize reacts with active metals such as aluminum, magnesium powders, potassium, and sodium reacts with strong oxidizers and concentrated nitric acid FP (none) LFL/UFL(13%, 23%) AT (556°C, 1033 F) HC (-513.9 kJ/mol) HF (124.1 kJ/gmol liquid at 25°C). 

This reaction was initially reported by Flood in 1933. It is a synthesis of trialkylsilyl halide involving the treatment of the mixture of di-trialkylsilyl oxide and concentrated sulfuric acid with sodium halide or ammonium halide. The resulting trialkylsilyl halide can be extracted by petroleum ether and then purified via distillation. It was found that when di-trimethylsilyl oxide is mixed with concentrated sulfuric acid, trimethylsilyl sulfate can be isolated as a white crystalline (m.p., Sb-SS C), which forms trimethylsilyl halide when it reacts with ammonium halide. The reaction has been improved by continuous extraction of the reaction mixture with pentane to yield more and purer trialkylsilyl halide and by the addition of ammonium bisulfate to the reaction mixture. ... 

So manner of equation (35) shows that in the initial stage reaction oxidation of the amount of oxygen absorbed during oxidation, and concentration hydroperoxide proportional to the square of oxidation time. This is consistent with the conclusion drawn in previous work (Emanuel N.M., Buchachenko A.L.,1982). Comparison (36) and (37) provided in the form of dependence changes in the concentration oxygen from the oxidation time ... 

When manganese(IV) oxide and concentrated sulfuric acid are added to a chloride, chlorine gas is produced (this is similar to the reaction of concentrated hydrochloric acid and manganese(IV) oxide). For example ... 

FIGURE 1.182 Relationships between adsorption of proteins (in mg per of surface area of oxide) and concentration of adsorbed water (a) weakly bound (desorbed at 7 <105°C) and (b) summary amount desorbed from room temperature up to 900°C. (Adapted from Colloids Surf. A Physicochem. Eng. Aspects, 180, Mironyuk, I.F., Gun ko, V.M., Turov, NN., Zarko, V.L, Leboda, R., and Skubiszewska-Zi ba, J. et al.. Characterization of fumed silicas and their interaction with water and dissolved proteins, 87-101, 2001. Copyright 2001, with permission from Elsevier.)... 

For the separation of I with carrier from deuteron-irradlated tellurium, the target was dissolved In a mixture of chromluin(VI) oxide and concentrated sulfuric acid. Solid oxalic acid and Iodide carrier were added to the solution and the molecular Iodine formed was swept from the solution by the carbon dioxide liberated from the oxalic add. The Iodine was converted to Iodide by collection In an alkaline solution of sodium sulfite. 

Recovery from Elemental Te(169). The tellurium was dissolved in a mixture of chromium(VI) oxide and concentrated sulfuric acid or in one of potassium dichromate and the acid. The periodate formed was reduced to elemental iodine by oxalic acid and the iodine distilled into a solution containing sulfite or thiosulfate. The iodide in solution was oxidized with permanganate and then reduced to the free condition with oxalic acid. The element was again distilled into a reducing solution. Yields up to 90% were obtained. 

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