Isopropylbenzene Cumene Hydroperoxide

The most widely used process for the production of phenol is the cumene process developed and Hcensed in the United States by AHiedSignal (formerly AHied Chemical Corp.). Benzene is alkylated with propylene to produce cumene (isopropylbenzene), which is oxidized by air over a catalyst to produce cumene hydroperoxide (CHP). With acid catalysis, CHP undergoes controUed decomposition to produce phenol and acetone a-methylstyrene and acetophenone are the by-products (12) (see Cumene Phenol). Other commercial processes for making phenol include the Raschig process, using chlorobenzene as the starting material, and the toluene process, via a benzoic acid intermediate. In the United States, 35-40% of the phenol produced is used for phenoHc resins. 

Phenol is manufactured from the hydrocarbon, cumene. Cumene (isopropylbenzene) is oxidised in the presence of air to cumene hydroperoxide. It is converted to phenol and acetone by treating it with dilute acid. Acetone, a by-product of this reaction, is also obtained in large quantities by this method. 

CUMENE HYDROPEROXIDE alpha, alpha-DimethylbenzeneHydroperoxide, Dimethylbenzyl Hydroperoxide, Isopropylbenzene Hydroperoxide Organic Peroxide 1 2 4 oxy... 

Alkylation. Friedel-Crafts alkylation (qv) of benzene with ethylene or propylene to produce ethylbenzene [100-41 -4], CgH10, or isopropylbenzene [98-82-8], C9H12 (cumene) is readily accomplished in the liquid or vapor phase with various catalysts such as BF3 (22), aluminum chloride, or supported polyphosphoric acid. The oldest method of alkylation employs the liquid-phase reaction of benzene with anhydrous aluminum chloride and ethylene (23). Ethylbenzene is produced commercially almost entirely for styrene manufacture. Cumene [98-82-8] is catalytically oxidized to cumene hydroperoxide, which is used to manufacture phenol and acetone. Benzene is also alkylated with C1Q—C20 linear alkenes to produce linear alkyl aromatics. Sulfonation of these compounds produces linear alkane sulfonates (LAS) which are used as biodegradable deteigents. 

Cumene or isopropylbenzene, diisopropylbenzene, and secondary butyl-benzene, although produced in smaller quantities than some of the other petrochemical alkylates, are very important petroleum refining products. Cumene is further reacted by oxidation to form cumene hydroperoxide, which is converted to phenol and acetone it is produced by alkylating benzene with propylene catalyzed by either solid or liquid phosphoric acid. Secondary butylbenzene is made by alkylating benzene with normal butylene using the same catalysts. Diisopropylbenzene is made by reacting cumene with propylene over solid phosphoric acid or aluminum chloride catalyst. 

Most phenol nowadays is obtained from isopropylbenzene (cumene), which is oxidized by air in the cumene proces.s (Scheme 4.1). Acetone (propanone) is a valuable by-product of the process and this route is a major source of this important solvent. The formation of cumene hydroperoxide proceeds by a free radical chain reaction initiated by the ready generation of the tertiary benzylic cumyl radical, which is a further illustration of the ease of attack at the benzylic position, especially by radicals (see Chapter 3). 

On an industrial scale, phenol is obtained by the oxidation of isopropylbenzene (cumene). Initially a hydroperoxide is formed, which then undergoes a fragmentation and rearrangement. The initial oxidation illustrates the susceptibility of benzylic positions to oxidative, particularly radical, attack (Scheme 4.14). 

Such reactions take place with p-xylene [28], ethylbenzene [28], and especially readily with isopropylbenzene (cumene) [29], where the intermediate free radical is stabilized not only by the aromatic ring but also by the two adjacent methyl groups. The oxidation of cumene to cumyl hydroperoxide (equation 162) followed by acid treatment is a basis for the large-scale production of phenol. 

An increasingly important process for the synthesis of phenol starts with cumene, isopropylbenzene. Cumene is converted by air oxidation into cumene hydroperoxide, which is converted by aqueous acid into phenol and acetone. 

For many years, phenol was manufactured b the Dow process, in which chlorobenzene reacts with NaOH at high temperature and pressure (Section 16.9). Now, however, an alternative synthesis from isopropylbenzene (cumene) is used. Cumene reacts with air at high temperature by a radical mechanism to form cumene hydroperoxide, which is converted into phenol and acetone by treatment with acid. This is a particularly efficient process because two valuable chemicals are prepared at the same time. 

In a new process for making phenol, cumene (isopropylbenzene) is oxidized with air to form cumene hydroperoxide, which is then changed to phenol and acetone. The cumene is made by the direct alkylation of gaseous benzene, using a phosphoric acid-kieselguhr catalyst and operating conditions of 500 K. 

Alkylation of benzene with propene to isopropylbenzene (cumene), oxidation of cumene to the corresponding tert-hydroperoxide and cleavage to phenol and acetone (Hock process). 

Several approaches are currently used to produce cyclohexanone. Two autoxidative processes which are relevant to this presentation will be discussed here. First, we will discuss the AlliedSignal process. In this approach, cumene (isopropylbenzene) is reacted with air at 105 at 5 psig to form cumene hydroperoxide. The conversion is slow but the selectivity is high approaching 100%. The hydroperoxide when heated at 77 with sulfuric acid, rearranges to form equimolar amounts of phenol and acetone. Phenol is then reduced at 155 by hydrogen at 80 - 220 psig in the presence of Pd on carbon to form cyclohexanone. About 10% of cyclohexanol is also formed. 

Under certain controlled conditions, it is possible to obtain substantial yields of peroxides and hydroperoxides from the mr oxidation of hydrocarbons. Commercially available peroxides obtained from liquid-phase air oxidation of hydrocarbons are sold under the name Uniperox and find use as diesel-fuel additives and polymerization catalysts. Thus the autoxida-tion of isopropylbenzene (cumene) at elevated temperatures and ivith brief ultraviolet irradiation is comparatively rapid, occurring at the labile H atom of the isopropyl group. 

Isopropylbenzene (Cumene). Oxidation of isopropylbenzene, cumene, to cumene hydroperoxide and the subsequent decomposition to phenol and acetone have become of significant commercial importance in recent years and have, furthermore, pointed the way as a generally useful new route for potential commercial manufacture of other important chemicals. For use in the phenol-plus-acetone process, cumene is usually obtained by the phosphoric acid-catalyzed alkylation of benzene with propylene. 

In the cumene process, benzene is first converted, via the action of propene, to isopropylbenzene (cumene) in a Friedel-Crafts type reaction. Catalysts such as AICI3, sulfuric acid, or phosphoric acid are necessary. Treating cumene with oxygen results in the formation of a hydroperoxide at the tertiary C atom, and this can be decomposed to phenol and acetone. 

From Cumene Hydroperoxide. This process illustrates industrial chemistry at its best. Overall, it is a method for converting two relatively inexpensive organic compounds— benzene and propene—into two more valuable ones—phenol and acetone. The only other substance consumed in the process is oxygen from air. Most of the worldwide production of phenol is now based on this method. The synthesis begins with the Friedel-Crafts alkylation of benzene with propene to produce cumene (isopropylbenzene) ... 

Isobutyl Hethyl Carbinol Methyl Isobutyl Carbinol Isopropylbenzene Hydroperoxide Cumene Hydroperoxide... 

The action mechanism of sulphur-containing antioxidants was studied by the well-established method of following O2 uptake with time as a function of added inhibitor (antioxidant). The effect of antioxidants that inhibit chain termination and also ones exhibit hydroperoxide decomposition activity were evaluated. Isopropylbenzene (cumene) was used as the representative organic reactant (e.g. Fig. 9.1) and the reaction was initiated by azodiisobutyronitrile in the presence of the other reactants at 60°C. 

X,(X-Dimethylbenzyl hydroperoxide, SCI. Isopropylbenzene hydroperoxide. Cumene hydroperoxide. 2-Hydroperoxy-2-phenylpropane [80-15-9]... 

Obtained synthetically by one of the following processes fusion of sodium ben-zenesulphonate with NaOH to give sodium phenate hydrolysis of chlorobenzene by dilute NaOH at 400 C and 300atm. to give sodium phenate (Dow process) catalytic vapour-phase reaction of steam and chlorobenzene at 500°C (Raschig process) direct oxidation of cumene (isopropylbenzene) to the hydroperoxide, followed by acid cleavage lo propanone and phenol catalytic liquid-phase oxidation of toluene to benzoic acid and then phenol. Where the phenate is formed, phenol is liberated by acidification. 

Cumene (isopropylbenzene) is made by Friedel-Crafts alkylation of benzene with propylene. Although cumene is a high-octane automotive fuel, almost all of the cumene produced is used to make phenol (C6H5OH) and acetone [(CH3)2CO]. Cumene is easily oxidized to the corresponding hydroperoxide, which is readily cleaved in dilute acid, to yield phenol and acetone. 

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