Hydroperoxide, cumyl

SULFURIC AND SULFUROUS ESTERS] (Vol 23) m/p-Isopropyl-a-cumyl hydroperoxide [98-49-7]... 

Commercially, autoxidation is used in the production of a-cumyl hydroperoxide, tert-huty hydroperoxide, -diisopropylbenzene monohydroperoxide, -diisopropylbenzene dihydroperoxide, -menthane hydroperoxide, pinane hydroperoxide, and ethylbenzene hydroperoxide. 

The following commercially available dialkyl peroxides are produced according to equations 24—27 di-Z fZ-butyl peroxide from hydrogen peroxide and sulfated tert-huty alcohol or isobutylene dicumyl peroxide from a-cumyl hydroperoxide and cumyl alcohol, cumyl chloride, and/or a-methylstyrene m- and -di(2-/ f2 -butylperoxyisopropyl)ben2ene [2781-00-2] from tert-huty hydroperoxide [75-91-2] and m- and -di(2-hydroxyisopropyl)ben2ene ... 

Carbo- and heterocyclic nitroarenes react v/ith anions of rerr-butyl and cumyl hydroperoxides in the presence of strong bases to form snbsdtuted o- and -nitrophenols Regiochemistry of the hydtoxyladon can be controlled to a snbstandM extent by selecdon of proper conthdons fEq 9 53 ... 

Principally, both unifold and twofold transformation types ensue in these cases. A unifold transformation occurs in the case of the rearrangement of cumyl benzenesulfinate, which arises from the conversion of cumyl hydroperoxide with benzenesulfenyl chloride23 (equation 2). Closely related sulfoxylate-sulfone rearrangements, which pass intermediate sulfinate steps similarly, are equally known24,25. 

A non-kinetic study of the oxidation of cumyl hydroperoxide by Pb(lV) to acetophenone and dimethylphenylcarbinol gives useful complementary data. 

This difunctional analogue of cumyl hydroperoxide appears to be no more hazardous that the latter. Though impact-sensitive, the decomposition was mild and incomplete. 

Ozone chain decomposition occurs in the reaction of ozone with cumyl hydroperoxide [146]. The rate of this reaction is... 

The analysis of the IR spectrum of hydrogen peroxide and cumyl hydroperoxide gave the following values of frequencies (cm-1) of valence and bond angle vibrations [60]. 

Acids are well known as efficient catalysts of various heterolytic reactions (hydrolysis, esterification, enolyzation, etc. [225,226]). They catalyze the heterolytic decay of hydroperoxides formed during oxidation. For example, they catalyze the decomposition of cumyl hydroperoxide into phenol and acetone (important technological reaction) [5]. 

The reaction of olefin epoxidation by peracids was discovered by Prilezhaev [235]. The first observation concerning catalytic olefin epoxidation was made in 1950 by Hawkins [236]. He discovered oxide formation from cyclohexene and 1-octane during the decomposition of cumyl hydroperoxide in the medium of these hydrocarbons in the presence of vanadium pentaoxide. From 1963 to 1965, the Halcon Co. developed and patented the process of preparation of propylene oxide and styrene from propylene and ethylbenzene in which the key stage is the catalytic epoxidation of propylene by ethylbenzene hydroperoxide [237,238]. In 1965, Indictor and Brill [239] published studies on the epoxidation of several olefins by 1,1-dimethylethyl hydroperoxide catalyzed by acetylacetonates of several metals. They observed the high yield of oxide (close to 100% with respect to hydroperoxide) for catalysis by molybdenum, vanadium, and chromium acetylacetonates. The low yield of oxide (15-28%) was observed in the case of catalysis by manganese, cobalt, iron, and copper acetylacetonates. The further studies showed that molybdenum, vanadium, and... 

Hock and Kropf [253] studied cumene oxidation catalyzed by Pb02. They proposed that Pb02 decomposed cumyl hydroperoxide (ROOH) into free radicals (R0 , R02 ). The free radicals started the chain oxidation of cumene in the liquid phase. Lead dioxide introduced into cumene was found to be reduced to lead oxide. The reduction product lead oxide was found to possess catalytic activity. The following tentative mechanism was proposed. 

By the free radical acceptor method in the decomposition of cumyl hydroperoxide catalyzed by Fe203 (343 K, 0.25 g cm-3 Fe203, ionol as acceptor of free radicals [257])... 

By the CL method in the oxidation catalyzed by Fe203 decomposition of cumyl hydroperoxide [258]... 

The effect of jumping of the maximal hydroperoxide concentration after the introduction of hydrogen peroxide is caused by the following processes. The cumyl hydroperoxide formed during the cumene oxidation is hydrolyzed slowly to produce phenol. The concentration of phenol increases in time and phenol retards the oxidation. The concentration of hydroperoxide achieves its maximum when the rate of cumene oxidation inhibited by phenol becomes equal to the rate of hydroperoxide decomposition. The lower the rate of oxidation the higher the phenol concentration. Hydrogen peroxide efficiently oxidizes phenol, which was shown in special experiments [8]. Therefore, the introduction of hydrogen peroxide accelerates cumene oxidation and increases the yield of hydroperoxide. 

The experiments on emulsion cumene oxidation with AIBN as initiator proved that oxidation proceeds via the chain mechanism inside hydrocarbon drops [17]. The presence of an aqueous phase and surfactants compounds does not change the rate constants of chain propagation and termination the ratio (fcp(2fct)-1/2 = const in homogeneous and emulsion oxidation (see Chapter 2). Experiments on emulsion cumene oxidation with cumyl hydroperoxide as the single initiator evidenced that the main reason for acceleration of emulsion oxidation versus homogeneous oxidation is the rapid decomposition of hydroperoxide on the surface of the hydrocarbon and water drops. Therefore, the increase in the aqueous phase and introduction of surfactants accelerate cumene oxidation. 

The kinetic study of cumyl hydroperoxide decomposition in emulsion showed that (a) hydroperoxide decomposes in emulsion by 2.5 times more rapidly than in cumene (368 K, [RH] [H20] = 2 3 (v/v), 0.1 N Na2C03) and (b) the yield of radicals from the cage in emulsion is higher and close to unity [19]. The activation energy of ROOH decomposition in cumene is Ed = 105 kJ mol-1 and in emulsion it is lower and equals Ed 74 kJ mol 1 [17]. 

FIGURE 11.1 The kinetic curves of cumyl hydroperoxide formation in emulsion oxidation of cumene [8] at T — 358 K, H20 RH — 3 l (v/v) 1 N Na2C03 with input of 0.015mol L 1 H202 in the moments designated by arrows (curve 1), after 8 h (curve 2), and after 4 h (curve 3). 

The flash photolysis study of the reaction of Ph2N with cumyl hydroperoxide showed the more sophisticated mechanism of this reaction [99]. When [ROOH] is low (less than 0.01 mol L-1), the reaction proceeds as bimolecular. The mechanism changes at the hydroperoxide concentration greater than 0.02mol L-1. The diphenylaminyl radical forms complex with hydroperoxide, and the reaction proceeds through the electron transfer. 

In polar solvents, this reaction is fast. For instance, at 333 K/ -methoxyphenol is oxidized by cumyl hydroperoxide in chlorobenzene and a mixture of chlorobenzene tert-butanol = 4 1 with kn = 3.5 x 10-6 and 2.5 x 10-4 Lmol-1 s 1, respectively [124]. The acceleration of this... 

Hydroperoxides oxidize aromatic amines more readily than analogous phenols. Thus, at 368 K cumyl hydroperoxide oxidizes a-naphthylamine and a-naphthol with ku = 1.4 x 10 4 and 1.7 x 10 5L mol-1 s 1, respectively [115,118], The oxidation of amines with hydroperoxides occurs apparently by chain mechanism, since the step of free radical generation proceeds much more slowly. This was proved in experiments on amines oxidation by cumyl hydroperoxide in the presence of /V,/V -diphcnyl-l, 4-phcnylcnediamine (QH2) as a radical acceptor [125]. The following reactions were supposed to occur in solution (80% decane and 20% chlorobenzene) ... 

The stoichiometry of this reaction is usually close to unity [6-9]. Thus, cumyl hydroperoxide oxidizes triphenyl phosphite in the stoichiometry A[ROOH]/A[Ph3P] from 1.02 1 to 1.07 1, depending on the proportion between the reactants [6], The reaction proceeds as bimolecular. The oxidation of phosphite by hydroperoxide proceeds mainly as a heterolytic reaction (as follows from conservation of the optical activity of reaction products [5,11]). Oxidation is faster in more polar solvents, as evident from the comparison of k values for benzene and chlorobenzene. Heterolysis can occur via two alternative mechanisms... 

These reactions produce free radicals, as follows from the fact of consumption of free radical acceptor [42]. The oxidation of ethylbenzene in the presence of thiophenol is accompanied by CL induced by peroxyl radicals of ethylbenzene [43]. Dilauryl dithiopropionate induces the pro-oxidative effect in the oxidation of cumene in the presence of cumyl hydroperoxide [44] provided that the latter is added at a sufficiently high proportion ([sulfide]/[ROOH] > 2). By analogy with similar systems, it can be suggested that sulfide should react with ROOH both heterolytically (the major reaction) and homolytically producing free radicals. When dilauryl dithiopropionate reacts with cumyl hydroperoxide in chlorobenzene, the rate constants of these reactions (molecular m and homolytic i) in chlorobenzene are [42]... 

The reactions of sulfides with ROOH give rise to products that catalyze the decomposition of hydroperoxides [31,38-47]. The decomposition is acid-catalyzed, as can be seen from the analysis of the resulting products cumyl hydroperoxide gives rise to phenol and acetone, while 1,1-dimethylethyl hydroperoxide gives rise to 1,1-dimethylethyl peroxide, where all the three are the products of acid-catalyzed decomposition [46-49]. It is generally accepted that the intermediate catalyst is sulfur dioxide, which reacts with ROOH as an acid [31,46-50]. 

Metal dialkyl dithiocarbamates inhibit the oxidation of hydrocarbons and polymers [25,28,30,76 79]. Like metal dithiophosphates, they are reactive toward hydroperoxides. At room temperature, the reactions of metal dialkyl dithiocarbamates with hydroperoxides occur with an induction period, during which the reaction products are formed that catalyze the breakdown of hydroperoxide [78]. At higher temperatures, the reaction is bimolecular and occurs with the rate v = k[ROOH][inhibitor]. The reaction of hydroperoxide with dialkyl dithiocarbamate is accompanied by the formation of radicals [30,76,78]. The bulk yield of radicals in the reaction of nickel diethyl dithiocarbamate with cumyl hydroperoxide is 0.2 at... 

Of several procedures for the stereoselective oxidation of sulfides using organometallic complexes, two adaptations of Kagan s original process have gained prominence. In the first method the diol (36) is reacted with Ti(0 Pr)4 to form the catalyst. With cumyl hydroperoxide as the stoichiometric oxidant, methyl para-tolyl sulfide was converted into the optically active sulfoxide in 42 % yield (98 % ee)[109]. 

Furylhydroperoxides of type 1 or cumyl hydroperoxide can be used according to the particular sulfoxide to be resolved. Other procedures, involv-... 

If cyclohexanecarboxaldehyde is incubated with CYP2B4, NADPH, and cytochrome P450 reductase, the aldehyde-cyclohexyl ring carbon-carbon bond is cleaved generating cyclohexene and formic acid (150) (Fig. 4.81). The reaction is supported if hydrogen peroxide replaces NADPH and cytochrome P450 reductase but is not supported if other oxidants at the same oxidation equivalent as peroxide but bypass the peroxy form of P450 such as iodosobenzene, m-chloroperbenzoic acid, or cumyl hydroperoxide are used. These... 

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