Abstract:The kinetic model of the ethyl benzene oxidation was applied to the design of the large-scale reactors of p-nitroacetophenone (chloramphenicol key intermediate) synthesis by p-nitroethyl benzene oxidation and benzoic acid synthesis by acetophenone oxidation. The factors allowing simplification of the above model are discussed. The height of the frothy (aerated) liquid layer in the oxidation tower securing the explosion-proof reaction conditions of acetophenone and p-nitroethyl benzene oxidation both in the kin… Show more
“…Thus, it was necessary to study both the anaerobic oxidation of AP by Mn 3+ ions using Mn(OAc) 3 ·2H 2 O under Ar atmosphere and its oxidation to benzoic acid by oxygen in the presence of Mn(OAc) 2 ·4H 2 O catalyst. The formation of complexes in the system Mn 3+ −Mn 2+ −AP−BA has been studied earler, and the results obtained were used in the construction of the kinetic model. The results of UV spectroscopy showed that in the chloro- and dichlorobenzene solutions exist free ions Mn 3+ , Mn 2+ together with associates Mn 2+ ···Mn 2+ , Mn 3+ ···Mn 3+ , and Mn 3+ ···Mn 2+ .…”
A practical model was developed for liquid-phase Mn 3+catalysed oxidation of ethyl benzene by O 2 . The model describes time profiles of concentrations of ethyl benzene and two intermediate oxidation products (methyl phenyl carbinol and acetophenone). The kinetic model of acetophenone oxidation to benzoic acid was also obtained. The influence of the main products of the ethyl benzene oxidation on the reaction kinetics is discussed. It was established that the addition of ethyl benzene hydroperoxide does not affect the reaction rate; the addition of methyl phenyl carbinol inhibits the reaction. The addition of acetophenone promotes the reaction and neutralises the inhibiting effect of methyl phenyl carbinol. The proposed reaction mechanism includes free-radical ethyl benzene oxidation. The process is initiated by the acetophenone interaction with Mn 3+ ion, and the chain is propagated due to the hydroperoxide interaction with ethyl benzene. The chain termination is quadratic. The length of the oxidation chain was calculated. The inhibition is caused by the manganese bonding to form an inactive complex. The obtained system of differential rate equations adequately describes the process.
“…Thus, it was necessary to study both the anaerobic oxidation of AP by Mn 3+ ions using Mn(OAc) 3 ·2H 2 O under Ar atmosphere and its oxidation to benzoic acid by oxygen in the presence of Mn(OAc) 2 ·4H 2 O catalyst. The formation of complexes in the system Mn 3+ −Mn 2+ −AP−BA has been studied earler, and the results obtained were used in the construction of the kinetic model. The results of UV spectroscopy showed that in the chloro- and dichlorobenzene solutions exist free ions Mn 3+ , Mn 2+ together with associates Mn 2+ ···Mn 2+ , Mn 3+ ···Mn 3+ , and Mn 3+ ···Mn 2+ .…”
A practical model was developed for liquid-phase Mn 3+catalysed oxidation of ethyl benzene by O 2 . The model describes time profiles of concentrations of ethyl benzene and two intermediate oxidation products (methyl phenyl carbinol and acetophenone). The kinetic model of acetophenone oxidation to benzoic acid was also obtained. The influence of the main products of the ethyl benzene oxidation on the reaction kinetics is discussed. It was established that the addition of ethyl benzene hydroperoxide does not affect the reaction rate; the addition of methyl phenyl carbinol inhibits the reaction. The addition of acetophenone promotes the reaction and neutralises the inhibiting effect of methyl phenyl carbinol. The proposed reaction mechanism includes free-radical ethyl benzene oxidation. The process is initiated by the acetophenone interaction with Mn 3+ ion, and the chain is propagated due to the hydroperoxide interaction with ethyl benzene. The chain termination is quadratic. The length of the oxidation chain was calculated. The inhibition is caused by the manganese bonding to form an inactive complex. The obtained system of differential rate equations adequately describes the process.
“…It was also established that in ethylbenzene oxidation Mn 3+ accumulates in the reaction mixture during induction time and the acceleration of the reaction corresponds to this accumulation. In the case of p -nitroethylbenzene virtually all the Mn present transforms to Mn 3+ at the start of the reaction . Addition of peroxides at the start of ethylbenzene oxidation results in a rapid conversion of all present Mn ions to Mn 3+ , and thus reaction profiles are obtained that coincide with those after the induction time.…”
Section: Oxidation Of Hydrocarbons In Nonpolar Mediamentioning
The work discussed the role of cobalt and manganese complexes
in the liquid-phase catalytic benzylic oxidation in polar and
apolar media. Evidence that hydrocarbon is involved during
oxidation with the transition metal ion is presented. It is
supposed that reaction acceleration caused by bromide salts is
due to the increase in the rate of the electron transfer and no
initiation by bromine atoms exist. The reasons for different
product selectivity in the presence of cobalt and manganese are
explained and the synergistic effects of mixed catalysts are
discussed. Thus cobalt is active in the oxidation of hydrocarbons
and alcohols, while manganese is active in oxidation of carbonyl
compounds. These assumptions allowed to build a system of
differential rate equations.
“…Using hydrogen peroxide and a tungsten catalyst, cyclohexanol is oxidized to cyclohexanone, a Baeyer−Villiger oxidation occurs followed by hydrolysis, and the product hydroxyl acid is oxidized further to the diacid ( 306 ). The oxidation of ethylbenzene to benzoic acid using oxygen and a manganese catalyst was reported, and the kinetics of this process were studied carefully. − 71 Baeyer−Villiger Oxidations in Oxidation Cascades…”
Section: 75 Baeyer−villiger Reactionmentioning
confidence: 99%
“…The oxidation of ethylbenzene to benzoic acid using oxygen and a manganese catalyst was reported, and the kinetics of this process were studied carefully. [134][135][136] Baeyer-Villiger oxidation in concert with benzylic oxidation was utilized to produce 311 from 310 (Scheme 72). 137 In the synthesis of a related compound (313), Lyttle also employed a Baeyer-Villiger oxidation of aldehyde 312.…”
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