Oxidation Of Isopropylbenzene Research Articles

Construction and use of an ipb DNA module to generate Pseudomonas strains with constitutive trichloroethene and isopropylbenzene oxidation activity.

Pseudomonas sp. strain JR1 exhibits trichloroethene (TCE) oxidation activity with isopropylbenzene (IPB) as the inducer substrate. We previously reported the genes encoding the first three enzymes of the IPB-degradative pathway (ipbA1, ipbA2, ipbA3, ipbA4, ipbB, and ipbC) and identified the initial IPB dioxygenase (IpbA1 A2A3A4) as responsible for TCE cooxidation (U. Pflugmacher, B. Averhoff, and G. Gottschalk, Appl. Environ. Microbiol. 62:3967-3977, 1996). Primer extension analyses revealed multiple transcriptional start points located upstream of the translational initiation codon of ipbA1. The transcription from these start sites was found to be IPB dependent. Thirty-one base pairs upstream of the first transcriptional start point tandemly repeated DNA sequences overlapping the -35 region of a putative sigma 70 promoter were found. These repeats exhibit significant sequence similarity to the operator-promoter region of the xyl meta operon in Pseudomonas putida, which is required for the binding of XylS, a regulatory protein of the XylS (also called AraC) family. These similarities suggest that the transcription of the IPB dioxygenase genes is modulated by a regulatory protein of the XylS/AraC family. The construction of an ipb DNA module devoid of this ipb operator-promoter region and the stable insertion of this DNA module into the genomes of different Pseudomonas strains resulted in pseudomonads with constitutive IPB and TCE oxidation activities. Constitutive TCE oxidation of two such Pseudomonas hybrid strains, JR1A::ipb and CBS-3::ipb, was found to be stable for more than 120 generations in antibiotic-free medium. Evaluation of constitutive TCE degradation rates revealed that continuous cultivation of strain JR1A::ipb resulted in a significant increase in rates of TCE degradation.

Oxidation of isopropylbenzene by iron tetraphenylporphyrin: evidence for the interaction of the cumyl radical with oxygen donors

Evidence is presented for an unprecedented oxygen transfer from oxygen donors to a cumyl radical in the oxidation of isopropylbenzene catalysed by tetraphenyl metalloporphyrins.

Zeolite effect on the oxidation of hydrocarbons with irradiated TiO2semiconductor

The effect of an acidic zeolite on the photocatalytic oxidation of isopropylbenzene and α-methylstyrene over irradiated TiO2 leads to either an increase or a decrease in oxidation rate depending on the substrate but, in both cases, an increase in selectivity is observed.

Gas-phase oxidation of isopropylbenzene at high temperature

Etude de l'oxydation du cumene afin de determiner les reactions principales d'elimination du groupe isopropyl

Mechanism of the inhibition of oxidation by metal complexes

1. A study has shown that tin tetraiodide repeatedly breaks the oxidation chains in the initiated oxidation of isopropylbenzene at 50–75‡C. Inhibition involves stoichiometric chain rupture through homolytic substitution of the iodine of SnI4 by peroxyl radicals, followed by multiple chain rupture by molecular iodine and alkyl iodides in processes involving alkyl and peroxyl radicals. 2. Stoichiometric coefficients and rate constants have been determined for the reactions of peroxyl and alkyl radicals with SnI4 and molecular iodine, respectively.

Mechanism of the retardation of oxidation reactions by metal complexes

1. The antioxidant efficiency of nickel complexes containing coordinated amino groups is both due to chain breaking in the reaction with peroxyl radicals and to decomposition of hydroperoxides with a low yield of free radicals in bulk. 2. The rate constants for chain breaking for oxidation of isopropylbenzene and decomposition of the branching agent by nickel bis-(N-phenyl-o-aminobenzoate) and bis(N-benzaliminyl-o-aminobenzoate) were measured.

Gas chromatographic analysis of products obtained by the oxidation of isopropylbenzene

Various conditions for the chromatographic analysis of mixtures containing up to 90% cumenehydroperoxide (CHP) are described. It is shown that the analysis may be performed both on glass and stainless steel columns. The effect of metal injection ports and syringes on the stability of CHP depends on the material of which they are made. The relative error of CHP, dimethyl phenylcarbinol, acetophenone, phenol and isopropylbenzene in synthetic mixtures and the reproducibility of the same compounds in samples from a phenol plant are calculated.

Interaction of peroxide radicals with esters of hydroxylamines

1. Alkoxy derivatives of 2,2,6,6-tetramethylpiperidine interact with peroxide and alkoxyl radicals, forming the corresponding nitroxyl radicals. The kinetic criterion of effectiveness of inhibition on account of regeneration of nitroxyl radicals was formulated. 2. Reacting with alkyl radicals, 2,2,6,6-tetramethylpiperidino-l-oxyl inhibits the process of oxidation of isopropylbenzene and cyclohexyl methyl ether. 3. 4,4'-Dimethoxydiphenylnitroxyl interacts both with peroxide and with alkyl radicals of cyclohexyl methyl ether.

Study of the initiation reaction in the oxidation of isopropylbenzene

Study of the initiation reaction in the oxidation of isopropylbenzene

On the role of the hydrogen bond in the liquid-phase oxidation of isopropylbenzene

On the role of the hydrogen bond in the liquid-phase oxidation of isopropylbenzene

Emulsion oxidation under pressure of alkyl aromatic hydrocarbons. III. Effectiveness of hydrogen peroxide in oxidation of isopropyl benzene and of 1,1-diphenyl ethane

Emulsion oxidation under pressure of alkyl aromatic hydrocarbons. III. Effectiveness of hydrogen peroxide in oxidation of isopropyl benzene and of 1,1-diphenyl ethane