Oxidants cumene hydroperoxide

Production of acetone by dehydrogenation of isopropyl alcohol began in the early 1920s and remained the dominant production method through the 1960s. In the mid-1960s virtually all United States acetone was produced from propylene. A process for direct oxidation of propylene to acetone was developed by Wacker Chemie (12), but is not beheved to have been used in the United States. However, by the mid-1970s 60% of United States acetone capacity was based on cumene hydroperoxide [80-15-9], which accounted for about 65% of the acetone produced. 

Cumene Hydroperoxide Process for Phenol and Acetone. Ben2ene is alkylated to cumene, which is oxidized to cumene hydroperoxide, which ia turn is cleaved to phenol and acetone. 

In the first step cumene is oxidized to cumene hydroperoxide with atmospheric air or air enriched with oxygen ia one or a series of oxidizers. The temperature is generally between 80 and 130°C and pressure and promoters, such as sodium hydroxide, may be used (17). A typical process iavolves the use of three or four oxidation reactors ia series. Feed to the first reactor is fresh cumene and cumene recycled from the concentrator and other reactors. Each reactor is partitioned. At the bottom there may be a layer of fresh 2—3% sodium hydroxide if a promoter (stabilizer) is used. Cumene enters the side of the reactor, overflows the partition to the other side, and then goes on to the next reactor. The air (oxygen) is bubbled ia at the bottom and leaves at the top of each reactor. 

An oxirane process utilizes ethylbenzene to make the hydroperoxide, which then is used to make propylene oxide [75-56-9]. The hydroperoxide-producing reaction is similar to the first step of cumene LPO except that it is slower (2,224,316—318). In the epoxidation step, a-phenylethyl alcohol [98-85-1] is the coproduct. It is dehydrated to styrene [100-42-5]. The reported 1992 capacity for styrene by this route was 0.59 X 10 t/yr (319). The corresponding propylene oxide capacity is ca 0.33 x 10 t/yr. The total propylene oxide capacity based on hydroperoxide oxidation of propylene [115-07-1] (coproducts are /-butyl alcohol and styrene) is 1.05 x 10 t/yr (225). 

Sales demand for acetophenone is largely satisfied through distikative by-product recovery from residues produced in the Hock process for phenol (qv) manufacture. Acetophenone is produced in the Hock process by decomposition of cumene hydroperoxide. A more selective synthesis of acetophenone, by cleavage of cumene hydroperoxide over a cupric catalyst, has been patented (341). Acetophenone can also be produced by oxidizing the methylphenylcarbinol intermediate which is formed in styrene (qv) production processes using ethylbenzene oxidation, such as the ARCO and Halcon process and older technologies (342,343). 

Cumene Process. There are several Hcensed processes to produce phenol which are based on cumene (qv) (1,8—11). AH of these processes consist of two fundamental chemical reactions cumene is oxidized with air to form cumene hydroperoxide, and cumene hydroperoxide is cleaved to yield phenol and acetone. In this process, approximately 0.46 kg of acetone and 0.75 kg of phenol are produced per kg of cumene feedstock. 

A typical phenol plant based on the cumene hydroperoxide process can be divided into two principal areas. In the reaction area, cumene, formed by alkylation of benzene and propylene, is oxidized to form cumene hydroperoxide (CHP). The cumene hydroperoxide is concentrated and cleaved to produce phenol and acetone. By-products of the oxidation reaction are acetophenone and dimethyl benzyl alcohol (DMBA). DMBA is dehydrated in the cleavage reaction to produce alpha-methylstyrene (AMS). 

Oxidation of cumene to cumene hydroperoxide is usually achieved in three to four oxidizers in series, where the fractional conversion is about the same for each reactor. Fresh cumene and recycled cumene are fed to the first reactor. Air is bubbled in at the bottom of the reactor and leaves at the top of each reactor. The oxidizers are operated at low to moderate pressure. Due to the exothermic nature of the oxidation reaction, heat is generated and must be removed by external cooling. A portion of cumene reacts to form dimethylbenzyl alcohol and acetophenone. Methanol is formed in the acetophenone reaction and is further oxidized to formaldehyde and formic acid. A small amount of water is also formed by the various reactions. The selectivity of the oxidation reaction is a function of oxidation conditions temperature, conversion level, residence time, and oxygen partial pressure. Typical commercial yield of cumene hydroperoxide is about 95 mol % in the oxidizers. The reaction effluent is stripped off unreacted cumene which is then recycled as feedstock. Spent air from the oxidizers is treated to recover 99.99% of the cumene and other volatile organic compounds. 

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. 

The cumene is oxidized to cymene hydroperoxide, which decomposes to cresols and acetone. The process is similar to phenol (qv) production from cumene. 

The oxidation step is similar to the oxidation of cumene to cumene hydroperoxide that was developed earlier and is widely used in the production of phenol and acetone. It is carried out with air bubbling through the Hquid reaction mixture in a series of reactors with decreasing temperatures from 150 to 130°C, approximately. The epoxidation of ethylbenzene hydroperoxide to a-phenylethanol and propylene oxide is the key development in the process. 

Production of a-methylstyrene (AMS) from cumene by dehydrogenation was practiced commercially by Dow until 1977. It is now produced as a by-product in the production of phenol and acetone from cumene. Cumene is manufactured by alkylation of benzene with propylene. In the phenol—acetone process, cumene is oxidized in the Hquid phase thermally to cumene hydroperoxide. The hydroperoxide is spHt into phenol and acetone by a cleavage reaction catalyzed by sulfur dioxide. Up to 2% of the cumene is converted to a-methylstyrene. Phenol and acetone are large-volume chemicals and the supply of the by-product a-methylstyrene is weU in excess of its demand. Producers are forced to hydrogenate it back to cumene for recycle to the phenol—acetone plant. Estimated plant capacities of the U.S. producers of a-methylstyrene are Hsted in Table 13 (80). 

Benzene is alkylated with propylene to yield cumene (qv). Cumene is catalytically oxidized in the presence of air to cumene hydroperoxide, which is decomposed into phenol and acetone (qv). Phenol is used to manufacture caprolactam (nylon) and phenoHc resins such as bisphenol A. Approximately 22% of benzene produced in 1988 was used to manufacture cumene. 

Oxidation of butyraldehyde to butyric acid [107-92-6]is most commonly carried out employing air or oxygen as the oxidant. Alternatively, organic oxidants, eg, cumene hydroperoxide, can also be employed effectively to give high yields of butyric acid, (4). 

Homogeneous Oxidation Catalysts. Cobalt(II) carboxylates, such as the oleate, acetate, and naphthenate, are used in the Hquid-phase oxidations of -xylene to terephthaUc acid, cyclohexane to adipic acid, acetaldehyde (qv) to acetic acid, and cumene (qv) to cumene hydroperoxide. These reactions each involve a free-radical mechanism that for the cyclohexane oxidation can be written as... 

More than 95% of the cumene produced is used as feedstock for the production of phenol (qv) and its coproduct acetone (qv). The cumene oxidation process for phenol synthesis has been growing in popularity since the 1960s and is prominent today. The first step of this process is the formation of cumene hydroperoxide [80-15-9]. The hydroperoxide is then selectively cleaved to phenol [108-95-2] and acetone [67-64-1/ in an acidic environment (21). 

The acetone supply is strongly influenced by the production of phenol, and so the small difference between total demand and the acetone suppHed by the cumene oxidation process is made up from other sources. The largest use for acetone is in solvents although increasing amounts ate used to make bisphenol A [80-05-7] and methyl methacrylate [80-62-6]. a-Methylstyrene [98-83-9] is produced in controlled quantities from the cleavage of cumene hydroperoxide, or it can be made directly by the dehydrogenation of cumene. About 2% of the cumene produced in 1987 went to a-methylstyrene manufacture for use in poly (a-methylstyrene) and as an ingredient that imparts heat-resistant quaUties to polystyrene plastics. 

A number of reaction variables or parameters have been examined. Catalyst solutions should not be prepared and stored since the resting catalyst is not stable to long term storage. However, the catalyst solution must be aged prior to the addition of allylic alcohol or TBHP. Diethyl tartrate and diisopropyl tartrate are the ligands of choice for most allylic alcohols. TBHP and cumene hydroperoxide are the most commonly used terminal oxidant and are both extremely effective. Methylene chloride is the solvent of choice and Ti(i-OPr)4 is the titanium precatalyst of choice. Titanium (IV) t-butoxide is recommended for those reactions in which the product epoxide is particularly sensitive to ring opening from alkoxide nucleophiles. ... 

Phenol, CeHsOH (hydroxybenzene), is produced from cumene by a two-step process. In the first step, cumene is oxidized with air to cumene hydroperoxide. The reaction conditions are approximately 100-130°C and 2-3 atmospheres in the presence of a metal salt catalyst ... 

In this process (Figure 10-6), cumene is oxidized in the liquid phase. The oxidation product is concentrated to 80% cumene hydroperoxide by... 

Anions of hydroperoxides may be used to successfully obtain sulphones by the oxidation of sulphoxides in non-aqueous media, without the use of transition metal catalysts. This is in contrast to oxidations with peracids where aqueous media are invariably used. Thus, dimethyl sulphoxide was oxidized by the anion of cumene hydroperoxide in ethanol or benzene solution at room temperature in 90% yield66. The yield is very much dependent on the base used and decreases along the series ... 

The most common precursor to phenolic resins is phenol. More than 95% of phenol is produced via the cumene process developed by Hock and Lang (Fig. 7.1). Cumene is obtained from the reaction of propylene and benzene through acid-catalyzed alkylation. Oxidation of cumene in air gives rise to cumene hydroperoxide, which decomposes rapidly at elevated temperatures under acidic conditions to form phenol and acetone. A small amount of phenol is also derived from coal. 

Induced reactions involving hydrogen peroxide can be observed with hydrogen peroxide derivatives, as well. For instance, the reaction between cumene hydroperoxide and iron(IT), in the absence of oxygen, results in a considerable induced decomposition of the peroxy compound, while, in the presence of oxygen, a marked oxidation of iron(II) takes place s . 

Organic peroxides such as cumene hydroperoxide and t-butyl hydroperoxide have extensively been used as experimental agents. They provoke lipid peroxidation in hepatocytes, probably by the generation of alkoxyl and peroxyl radical intermediates after reaction with cytochrome P450. Other cytotoxic mechanisms are probably involved including protein thiol and non-protein thiol oxidation and deranged calcium homeostasis (Jewell et al., 1986). In fact, the addition of cumene hydroperoxide to isolated bUe duct cells, devoid of cytochrome P450 activity, still results in cell death but lipid peroxidation is not detectable (Parola et al., 1990). 

The first line of evidence derives from the predominant formation of quinones when metabolism of BP is conducted under peroxi-datic conditions, namely by prostaglandin H synthase (21) or by cytochrome P-450 with cumene hydroperoxide as cofactor T22). Under these metabolic conditions one-electron oxidation is the preponderant mechanism of activation. 

As presented in Table II, no quinones are obtained with NADPH for dibenz[a,h]anthracene and benz[a]anthracene, whereas with cumene hydroperoxide a trace amount of benz[a]anthracene quinone is observed. For the PAH with low IP, quinones are formed in the presence of both cofactors. The relationship between IP and formation of quinones constitutes further evidence that these metabolites are obtained by an initial one-electron oxidation of the PAH with formation of its radical cation. 

The last reaction occurs much rapidly than the disproportionation of two cumylperoxyl radicals and accelerates chain termination in oxidized cumene [15]. The addition of cumene hydroperoxide helps to avoid the influence of the cross termination reaction Me2PhCOO + CH302 on the oxidation of cumene and to measure the pure disproportionation of cumylperoxyl radicals [15]. 

Emulsion oxidation of alkylaromatic compounds appeared to be more efficient for the production of hydroperoxides. The first paper devoted to emulsion oxidation of cumene appeared in 1950 [1], The kinetics of emulsion oxidation of cumene was intensely studied by Kucher et al. [2-16], Autoxidation of cumene in the bulk and emulsion occurs with an induction period and autoacceleration. The simple addition of water inhibits the reaction [6], However, the addition of an aqueous solution of Na2C03 or NaOH in combination with vigorous agitation of this system accelerates the oxidation process [1-17]. The addition of an aqueous phase accelerates the oxidation and withdrawal of water retards it [6]. The addition of surfactants such as salts of fatty acids accelerates the oxidation of cumene in emulsion [3], The higher the surfactant concentration the faster the cumene autoxidation in emulsion [17]. The rates of cumene emulsion oxidation after an induction period are given below (T = 353 K, [RH] [H20] = 2 3 (v/v), p02 = 98 kPa [17]). 

The rise in this ratio with the increasing number of tertiary C—H bonds in the molecule is explained by the increased probability of peroxyl radical undergoing isomerization. The experiments indicate that oxidized PP contains mainly block hydroperoxyl groups [12,88]. Hydrocarbons with tertiary C—H bonds (for example, isobutane, isopentane, and cumene) are oxidized in the liquid phase to stable molecular products, mainly hydroperoxides and A[02] = [ROOH], The recombination of tertiary peroxyl radicals gives rise to small amounts of dialkyl peroxide and alcohol (see Chapter 2). 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

Hock Also known as the Hock Lang process, and the cumene peroxidation process. A process for converting isopropyl benzene (cumene) to a mixture of phenol and acetone m-di-isopropyl benzene likewise yields resorcinol, and p-di-isopropyl benzene yields hydro-quinone. The basis of the process is the liquid-phase air oxidation of cumene to cumene hydroperoxide ... 

In the first of these techniques the lanthanoid complex (33) (5-8 mol%) is used as the organometallic activator in cumene hydroperoxide or tert-butyl hydrogen peroxide-mediated oxidation of chalcone (epoxide yield 99 % 99 % ee) or the ketone (34) (Scheme 20)[1001. 

The method is applicable to a wide range of substrates. Table 4.4 gives various a, (3-enones that can be epoxidized with the La-(R)-BINOL-Ph3PO/ROOH system. The substituents (R1 and R2) can be either aryl or alkyl. Cumene hydroperoxide can be a superior oxidant for the substrates with R2 = aryl group whereas t-butyl hydroperoxide (TBHP) gives a better result for the substrates with R1 = R2 = alkyl group. 

Shvedova, A.A., Tyurina, Y.Y., Kawai, K., Tyurin, V.A., Kommineni, C., Fabisiak, J.P., and Kagan, V.E., 2001, Selective peroxidation and extemalization of phosphatidylserine in normal human epidermal keratinocytes during oxidative stress induced by cumene hydroperoxide, J. Inv. Derm, (submitted for publication). 

This two-step process involves oxidation of cumene to cumene hydroperoxide, which decomposes with the help of a little dilute acid into phenol and acetone. In the first step, cumene is fed to an oxidation vessel (as shown in Figure 7—5)> where it is mixed with a dilute aqueous sodium carbonate solution (soda ash with a lot of water). A small amount of sodium stearate is added, and the whole mixture becomes an emulsion. ... 

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