Jan Zawadiak

Concurrent iodimetric determination of cumene hydroperoxide and dicumenyl peroxide used for reaction control in dicumenyl peroxide synthesis

A method for the iodimetric determination of cumene hydroperoxide (HPC) and dicumenyl peroxide (DC) has been established. This method makes possible the concurrent determination of these peroxides in mixtures containing also 2-phenylpropan-2-ol, acetophenone and cumene. While elaborating this method, advantage was taken of the difference in the reactivity of hydroperoxides and peroxides in their reaction with iodide ions, depending on the reaction temperature. The effect of the presence of DC on the results for HPC determinations was ascertained using statistical tests. The method can be used to analyse mixtures of other peroxides and hydroperoxides, provided that they are soluble in acetic acid.

Influence of substituent on UV absorption and keto-enol tautomerism equilibrium of dibenzoylmethane derivatives

UV absorption spectra of dibenzoylmethane and its 23 derivatives with acetamide, tert-butyl, chloride, fluoride, hydroxyl, methyl, methoxy and nitro substituents in aromatic rings were collected. General influence of substituent on absorption maxima and absorption intensity was defined. Hyperchromic effects were observed for diketones with electron-donating groups in para postion. The keto-enol tautomerism equilibrium constant of obtained compounds was investigated with (1)H NMR spectroscopy. Significant changes of equilibrium were observed only for ortho substituted compounds. Results revealed dissimilarity of substituent effects on absorption and keto-enol tautomerism of aromatic β-diketones.

Aerobic oxidation of cumene catalysed by 4-alkyloxycarbonyl-N-hydroxyphthalimide

Abstract4-Hexyloxycarbonyl-, 4-dodecyloxycarbonyl- and 4-hexadecyloxycarbonyl-N-hydroxyphthalimides were synthesised using trimellitic anhydride chloride as the starting material. The obtained lipophilic derivatives of N-hydroxyphthalimide were applied as catalysts of the cumene oxidation reaction with oxygen performed in polar acetonitrile, in non-polar tert-butylbenzene and in the absence of a solvent. The courses of reactions catalysed by N-hydroxyphthalimide and its derivatives were compared.

UV absorption and keto―enol tautomerism equilibrium of methoxy and dimethoxy 1,3-diphenylpropane-1,3-diones

UV absorption spectra of 1,3-diphenylpropane-1,3-dione (1), its three methoxy derivatives (2-4) and its six dimethoxy derivatives (5-10) in various solvents dissolved were collected. The keto-enol tautomerism equilibrium constant was calculated with (1)H NMR. The position of the methoxy group in 1,3-diphenylpropane-1,3-dione was shown to have an influence on the molecules UV absorption spectrum and the keto-enol tautomerism equilibrium constant. The methoxy group in the para position increases the absorption of radiation in the UV-A range. A shift to the keto form in the keto-enol tautomerism equilibrium is experienced by compounds with methoxy groups in ortho position. When two methoxy groups are present, the influence of their position is cumulative.

Oxidized Polyethylene Wax as a Potential Carbon Source for PHA Production

We report on the ability of bacteria to produce biodegradable polyhydroxyalkanoates (PHA) using oxidized polyethylene wax (O-PEW) as a novel carbon source. The O-PEW was obtained in a process that used air or oxygen as an oxidizing agent. R. eutropha H16 was grown for 48 h in either tryptone soya broth (TSB) or basal salts medium (BSM) supplemented with O-PEW and monitored by viable counting. Study revealed that biomass and PHA production was higher in TSB supplemented with O-PEW compared with TSB only. The biopolymers obtained were preliminary characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The detailed structural evaluation at the molecular level was performed by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The study revealed that, when TSB was supplemented with O-PEW, bacteria produced PHA which contained 3-hydroxybutyrate and up to 3 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units. The ESI-MS/MS enabled the PHA characterization when the content of 3-hydroxybutyrate was high and the appearance of other PHA repeating units was very low.

Polymer-Supported N-Hydroxyphthalimide as Catalyst for Toluene and p-Methoxytoluene Aerobic Oxidation

In the present study, N-hydroxyphthalimide (NHPI) was successfully immobilized on (aminomethyl) polystyrene and (chloromethyl) polystyrene via amide or ester bonds. The obtained polymer-supported NHPIs have demonstrated catalytic activity for the aerobic oxidation of toluene and p-methoxytoluene. The oxidations were performed using cobalt(II) salts as co-catalysts, in acetic acid as solvent or in more environmentally acceptable solvent-free system. The possibility of recovery and recycling of the obtained polymer-supported NHPIs was reported.Graphical Abstract

Copper salt-crown ether systems as catalysts for the oxidation of isopropyl arenes with tertiary hydroperoxides to peroxides

Abstract Symmetrical and unsymmetrical peroxides can be obtained by the oxidation of isopropyl arenes with tertiary hydroperoxides in the presence of copper salt–crown ether as catalysts. The efficiency of the investigated catalytic system enhances markedly in the presence of some alkali metal salts, with a cation diameter corresponding to the inner diameter of the crown ether. The oxidation of isopropyl arenes with hydroperoxides in the presence of a copper salt–crown ether–alkali metal salt catalytic system proved to be a simple and efficient method for the synthesis of ditertiary peroxides. A possible mechanism of this phenomenon is discussed. The results obtained confirm strongly that phase transfer catalysis operates in the investigated reaction.

Inverse gas chromatography investigation of oxidized polyolefins: Surface properties

Oxidized polyolefins were obtained in processes with the use of air or oxygen as oxidizing agent. The oxidation process caused partial polymer degradation and the change of the surface properties of examined materials. The magnitude of these changes was estimated by means of inverse gas chromatography. All oxidized materials were found to exhibit slightly acidic character. Surface properties strongly depend on the content of oxygen functional groups (oxidation degree) and type of initial material. The most active surfaces were found for oxidized polypropylene and polyethylene wax. The use of principal component analysis allowed to select four parameters offering complete information on the physiochemical character of examined materials (γS(D)), acid volume or saponification number, KA or KD and KA/KD.

A new efficient method for the processing of post-consumer polypropylene and other polyolefin wastes into polar waxes

This paper describes a new efficient method for the processing of post-consumer polypropylene (and other polyolefins) wastes into polar waxes that have potential applications. This technology includes two key steps. In the first step, the post-consumer polyolefins are purified mostly from oil which is used as a solvent in processing of polyolefin wastes (like metalized polyolefin films), and in the second step, the oxidative degradation process is initiated to obtain polar waxes or, alternatively, the purified polymer can be granulated. The results of laboratory research on both steps are presented, as well as a comparison of the obtained granulates and polar waxes with commercially available products.

Oxidation of 2-methoxy-6-(1-methylethyl)naphthalene with oxygen

Aerobic oxidation of 2-methoxy-6-(1-methylethyl)naphthalene to hydroperoxide, alcohol, and ketone, is reported. These compounds, particularly 2-acetyl-6-methoxynaphthalene, are important intermediates in naproxen synthesis. N-Hydroxyphthalimide is shown here to be an efficient catalyst for oxidation to the hydroperoxide, 2-methoxy-6-(1-hydroperoxy-1-methylethyl)naphthalene, with a yield of 87%. However, the ketone and alcohol were obtained with lower yields, with a maximum yield of 13% for the ketone and 27% for the alcohol, using N-hydroxyphthalimide and Cu(II) acetylacetonate as a catalyst. The synthesis of the products 2-acetyl-6-methoxynaphthalene and 2-methoxy-6-(1-hydroxy-1-methylethyl)naphthalene via an initial oxidation step to the hydroperoxide followed by a hydroperoxide decomposition step is shown to be more efficient; the ketone and alcohol were obtained from 2-methoxy-6-(1-methylethyl)naphthalene with yields of 40 and 56%, respectively.Graphical abstract