Decomposition Of Cumyl Hydroperoxide Research Articles

In situ EPR and Raman spectroscopy in the curing of bis-methacrylate–styrene resins

The curing of bis-methacrylate–styrene resins initiated by the cobalt catalyzed decomposition of cumyl hydroperoxide is monitored at ambient temperatures in situ by EPR and Raman spectroscopy. EPR spectroscopy shows the appearance of organic radicals after ca. 1 h from initiation with an increase in intensity from both polystyrene and methacrylate based radical species over a further ca. 2 h period to reach a maximum spin concentration of ca. 2–3 mM. Alkene conversion to polymer was monitored by Raman spectroscopy in real time in situ with EPR spectroscopy and reveals that the appearance of the radical signals is first observed only as the conversion approaches its maximum extent (70% at room temperature), i.e., the resin reaches a glass-like state. The radicals persist for several months on standing at room temperature. Flash frozen samples (77 K) did not show EPR signals within 1 h of initiation. The nature of the radicals responsible for the EPR spectra observed were explored by DFT methods and isotope labelling experiments (D8–styrene) and correspond to radicals of both methacrylate and polystyrene. Combined temperature dependent EPR and Raman spectroscopy shows that conversion increases rapidly upon heating of a cured sample, reaching full conversion at 80 °C with initially little effect on the EPR spectrum. Over time (i.e. subsequent to reaching full conversion of alkene) there was a small but clear increase in the EPR signal due to the methacrylate based radicals and minor decrease in the signal due to the polystyrene based radicals. The appearance of the radical signals as the reaction reaches completion and their absence in samples flash frozen before polymerization has halted, indicate that the observed radicals are non-propagating. The formation of the radicals due to stress within the samples is excluded. Hence, the observed radicals are a representative of the steady state concentration of radicals present in the resin over the entire timespan of the polymerization. The data indicate that the lack of EPR signals is most likely due to experimental aspects, in particular spin saturation, rather than low steady state concentrations of propagating radicals during polymerization.

Catalysis of Cumyl Hydroperoxide Decomposition by Calcium Salts and Complexes: A Kinetic Experiment and Quantum Chemical Modeling

The kinetic and thermodynamic parameters of the decomposition of cumyl hydroperoxide in a chlorobenzene medium in the presence of calcium 2-ethylhexanoate and a complex of CaCl2 with crown ether were experimentally obtained. The formation of intermediate complexes in the catalyst–hydroperoxide system was kinetically established. The formation of intermediate complexes was confirmed using quantum chemical modeling, their structure was optimized, and the thermodynamic characteristics of reactions with their participation were found. A mechanism of the stepwise decomposition of the intermediate was proposed.

Heterogeneous radical-generating catalysts based on cationic surfactants

Proceeding from the earlier finding that cationic surfactants are capable of forming mixed micelles with amphiphilic hydroperoxides (LOOH) and catalyzing their decomposition to free radicals, heterogeneous catalysts for the radical degradation of LOOH have been prepared by depositing the cationic surfactant cetyltrimethylammonium bromide (CTAB) onto the solid supports montmorillonite (M1), microcrystalline cellulose (Cel1), and chitosan (Chi1). The performance of the obtained colloid catalysts in generating radicals in a hydroperoxide-containing medium decreases in the order Cel1 > Chi1 > M1 for the radical chain styrene polymerization process in the presence of cumyl hydroperoxide or row Cel1 > M1 > Chi1 in the case of limonene oxidation. The low activity of M1 in the initiation of polymerization is probably due to partial heterolytic decomposition of cumyl hydroperoxide on montmorillonite to give phenol.

Cumyl hydroperoxide decomposition under the action of group II metal compounds

Cumyl hydroperoxide decomposition in chlorobenzene in the presence of magnesium, zinc, cadmium, or mercury 2-ethylhexanoate has been investigated. It has been established and kinetically proved that the decomposition reaction is preceded by the formation of a hydroperoxide-catalyst complex. Thermodynamic parameters of this complexation have been determined. The catalytic activity of the salts correlates with the ionization potentials of the metals.

Liquid-phase oxidation of benzothiophene and dibenzothiophene by cumyl hydroperoxide in the presence of catalysts based on supported metal oxides

The liquid-phase oxidation of benzothiophene and dibenzothiophene by cumyl hydroperoxide in the presence of supported metal oxide catalysts was carried out in octane in an N2 atmosphere at 50–80°C. The cumyl hydroperoxide, benzothiophene, and dibenzothiophene conversions and the yield of sulfones were determined for catalysts of various natures. In the presence of MoO3/SiO2, the most efficient and most readily regenerable catalyst, the benzothiophene conversion was ∼60% and the dibenzothiophene conversion was as high as 100% upon almost complete consumption of cumyl hydroperoxide. The influence of unsaturated and aromatic compounds (oct-1-ene, toluene) on the catalytic effect was studied. The kinetics of substrate oxidation and cumyl hydroperoxide decomposition and an analysis of the cumyl hydroperoxide conversion products suggested a benzothiophene and dibenzothiophene oxidation mechanism including the formation of an intermediate complex of the hydroperoxide with the catalyst and the substrate and its transformation via heterolytic and homolytic routes.

Homolytic decomposition of cumyl hydroperoxide under the action of zinc, cadmium, and mercury 2-ethylhexanoates

The free-radical decomposition of cumyl hydroperoxide (CHP) and the overall CHP decomposition process proceed via the same mechanism with similar kinetic parameters through the formation of a hydroperoxide-metal compound intermediate. The catalytic activity of metal ethylhexanoates decreases in the order Cd > Zn > Hg. The complex formation thermodynamics and decomposition kinetics are correlated with the metal ionization potentials, which are the lowest for cadmium. The zinc-family metals are catalytically more active than the Group IIA metals owing to their polarization effect. Within Group IIA, the catalytic properties are mainly determined by the nature of the interaction in the intermediate complex.

Electrochemical Study of the Reaction of Zinc Diisooctyldithiophosphate with Cumylhydroperoxide

Kinetics of a chemical reaction of cumylhydroperoxide with zinc diisooctyldithiophosphate (ZD) in dimethylformamide is studied by voltammetric techniques and a potentiometric method with a glass electrode. In the course of reaction, the activity of hydrogen ions first increases by two orders of magnitude and then decreases. The decomposition of cumylhydroperoxide during the second period is a second-order reaction, while the ZD transformation is a first-order reaction. In dimethyformamide, ZD is a weak electrolyte, and the current of its anodic oxidation is proportional to the square of the equilibrium concentration of diisooctyldithiophosphate ions.

Catalytic Decomposition of Cumyl Hydroperoxide under the Action of Aspartic Acid Derivatives

The inhibiting activity of aspartic acid derivatives in the stage of degenerate chain branching in decomposition of cumyl hydroperoxide was studied. The kinetic and thermodynamic parameters of the reaction were established.

Mechanism of the catalytic decomposition of cumyl hydroperoxide inhibited by 2-methylpropanol-1

The kinetics of cumyl hydroperoxide (CHP) decomposition catalyzed by molybdenyl propanediolate (Cat) and decomposition products are studied in the presence of 2-methylpropanol-1 (MP). Phenol, acetone, 2-phenylpropanol-2 (PhP), and acetophenone (APh) are the main products of cumyl hydroperoxide decomposition. The concentration of 2-methylpropanol-1 affects not only the ratio between the rates of heterolytic and homolytic decomposition of cumyl hydroperoxide, but also the ratio between the products of hydroperoxide homolysis, that is, the [2-phenylpropanol-2]/[acetophenone] ratio. The dissociation constants calculated for the catalyst-2-methylpropanol-1 and catalyst-2(2-methylpropanol-l) complexes are 0.275 and 4.910 mol/1, respectively. The exchange of hydroperoxide ligands in the ROH-catalyst-ROOH systems was studied by1H NMR spectroscopy. Exchange interactions affect the rate and direction of hydroperoxide decomposition

Effect of sulfur-containing phenols and amines on the decomposition of hydroperoxides

The effect of polyphenol sulfides (PPS) and dithiolthione, the sulfur-containing derivative of acetone anil, on the decomposition of cumyl andn-decyl hydroperoxides (DHP) studied. The decomposition of cumyl hydroperoxide (CHP) in the presence of PPS is a complex multistep autocatalytic process during which an efficient catalyst for CHP decomposition is formed from the initial PPS. The PPS catalyst for CHP decomposition is deactivated in the reaction with peroxy radicals. Kinetic characteristics of the reaction between polyphenol sulfides and CHP are determined. Dithiolthione catalytically decomposes CHP and reacts with n-decyl hydroperoxide DHP in the stoichiometric ratio

Thermochemical destruction of esters of 2-chloro-2-(1-cyclohexenyl) ethylenylphosphonic acid and their inhibitory properties

The thermal decomposition of four dialkyl esters of 2-chloro-2-(1-cyclohexenyl) ethylenylphosphonic acid has been investigated from room temperature to 600°C. This thermochemical decomposition proceeds as a three-step process. Independently of the thermal changes, the investigated esters inhibit the auto-oxidation process of cumene at 110°C. We followed the formation of the complexes of dibutyl ester and cumyl hydroperoxide, as a result of proton-donor interactions. These complexes affect cumyl hydroperoxide decomposition. It was established that the investigated esters catalysed the decomposition of cumyl hydroperoxide.

New possibilities of NMR in mechanistic studies of homogeneous and heterogeneous catalysis

Results are presented that demonstrate new possibilities provided by modern Fourier-transform NMR spectrometers in the mechanistic studies of both homogeneous and heterogeneous catalysis. As particular examples, are discussed: (1) in situ characterization of the intermediate alkylperoxo complexes of Mo(VI), V(V) and Co(III) in the course of homogeneous epoxidation of cyclohexene and oxidation of cyclohexane from simultaneously recorded 95Mo, 51V or 59Co NMR spectra and 1H, 17O NMR spectra. (2) in situ characterization of reaction intermediates from the rates of paramagnetic 1H and 13C nuclear relaxation in the course of homogeneous decomposition of cumyl hydroperoxide in the presence of μ 3-oxotricobalt (II,III,III) acetate and μ 3-oxotriruthenium (III) acetate and of propylene oxidation into propylene glycol by CuCl 2-I 2 catalytic system. (3) Characterization with 51V NMR of a family of V(V) sites in supported vanadium catalysts. (4) Elucidation from a combination of 13C CP/MAS NMR, 13C 2D/MAS NMR and 2H NMR of butyl silyl ether intermediates in the course of dehydration of butanols on H-ZSM-5 zeolite.

Phosphororganische Antioxidantien. III. Kinetik und Mechanismus der Cumylhydroperoxidzersetzung durch cyclische Phosphite

Organophosphorus Antioxidants. III. Kinetics and Mechanism of the Decomposition of Cumyl Hydroperoxide by Cyclic PhosphitesThe reaction mechanism of cyclic esters of phosphorous acids I to VIII with cumyl hydroperoxide has been studied kinetically by means of 31P n.m.r. spectroscopy, high performance liquid chromatography and iodometric titration.The five‐membered cyclic phosphites (I and II) react with cumyl hydroperoxide to give the corresponding phosphates (AI and AII) and cumyl alcohol. With more hydroperoxide or water they form the open chain phosphate esters (BI and BII) which decompose cumyl hydroperoxide catalytically giving phenol and acetone. Higher membered cyclic phosphites (III to VIII) react with cumyl hydroperoxide to give the corresponding phosphates and alcohol only. The mode of reaction depends on the hydrolysis behaviour of the cyclic phosphates (AI to A VIII). Only fivemembered cyclic phosphites which give easily hydrolyzable phosphates are able to decompose cumyl hydroperoxide catalytically. The nature of the exocyclic group in the phosphites has no influence on this behaviour.The kinetic parameters of the separate reaction steps are given.The ionic mechanism of hydroperoxide decomposition is accompanied by a homolytic one.

Kinetic relationships for the decomposition of cumyl hydroperoxide catalyzed by cobalt acetylacetonate in the presence of nitroxyl radicals

1. Using the scavenger 4-methyl-2-spirocyclohexyl-3,4,2′,3′-tetrahydrofurano-1,2,3,4-tetrahydroquinolin-1-oxyl the formation of peroxy radicals during the decomposition of cumyl hydroperoxide catalyzed by Co(acac)2 has been confirmed and their rate of formation has been measured. 2. The kinetic parametera, which characterizes the activity of radicals in chain propagation and termination reactions during the chain decomposition stage of cumyl hydroperoxide in the presence of Co(acac)2 has been determined.

Decomposition reactions of cumyl hydroperoxide with sulfur-containing metal complexes.

Decomposition reactions of cumyl hydroperoxide with metal complexes having both sulfur-containing chelates and phenolic moieties were carried out. Effects of chelates and/or of phenolic moieties on activities of metal complexes were studied. It was found that the phenolic moieties did not affect activities. The ESR measurements on the decomposition reactions showed that the reactions included homolytic decomposition of cumyl hydroperoxide. The homolytic decomposition was ascribable to a charge transfer and a redox reaction mechanism.

ChemInform Abstract: EFFECT OF THE POLARITY OF THE MEDIUM ON THE DECOMPOSITION OF CUMYL HYDROPEROXIDE AND CUMENE AUTOXIDATION IN THE PRESENCE OF COPPER(II)‐ACETYLACETONATE

Chemischer InformationsdienstVolume 10, Issue 18 Preparative Organic Chemistry ChemInform Abstract: EFFECT OF THE POLARITY OF THE MEDIUM ON THE DECOMPOSITION OF CUMYL HYDROPEROXIDE AND CUMENE AUTOXIDATION IN THE PRESENCE OF COPPER(II)-ACETYLACETONATE S. K. IVANOV, S. K. IVANOVSearch for more papers by this authorCHR. KARSHALYKOV, CHR. KARSHALYKOVSearch for more papers by this author S. K. IVANOV, S. K. IVANOVSearch for more papers by this authorCHR. KARSHALYKOV, CHR. KARSHALYKOVSearch for more papers by this author First published: May 1, 1979 https://doi.org/10.1002/chin.197918141AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue18May 1, 1979 RelatedInformation

Effect of the polarity of the medium on the decomposition of cumyl hydroperoxide and cumene autoxidation in the presence of Cu(II)-acetylacetonate

The effect of the polarity of the medium on the rate and the course of cumyl hydroperoxide (CHP) decomposition at 60 °C in the presence of copper acetylacetonate [Cu(acac) 2] as catalyst was investigated with the help of the radical-type inhibitor N-phenyl-2-naphthylamine (PNA). The influence on the oxidation rate of a mixture of cumene and nitrobenzene under analogous conditions was also studied. It was shown that the effect of Cu(acac) 2 on the decomposition of CHP is different from that of Co(acac) 2 catalyst investigated previously. Whereas Co(acac) 2 leads to the formation of free radicals only, a molecular course of the CHP decomposition was also observed in the presence of Cu(acac) 2. The values of the initial rates of the decomposition of CHP ( W in CHP) and of the consumption of PNA ( W in PNA) decrease with increase of the dielectric constant of the medium. However, the ratio between these rates remains independent of the change of the polarity of the medium. This fact shows that the dielectric constant does not affect the direction of the decomposition of CHP to molecular and to radical products.

Heterolytic decomposition of cumyl hydroperoxide in the presence of zinc di-isopropyl dithiophosphate

1. 1. A study was made of the decomposition of cumyl hydroperoxide in n-decane at 90° in the presence of zinc dii-isopropyl dithiophosphate, phosphorus pentasulphide, bis-(di-isopropylthion phosphoryl)-disulphide, di-isopropyldi-thiophosphoric acid, di-isobutylphosphoric acid, sulphuric and phosphoric acids, sulphur dioxide and dimethylsulphoxide. 2. 2. It was shown that in the presence of dithiophosphoric acid, zinc di-isopropyldithiophosphate, bis-(di-isopropylthionphosphoryl)-disulphide and phosphorus pentasulphide hydroperoxide undergoes autocatalytic decomposition. The rate of decomposition of hydroperoxide with SO 2 is about the same as the rate of decomposition in the rapid stage of the reaction in the presence of zinc di-isopropyldithiophosphate, while in the presence of H 2SO 4, it is about the same as the rate of decomposition of hydroperoxide with bis-(di-isopropylthionphosphoryl) -disulphide. H 3PO 4, di-isobutylphosphoric acid and (CH 3) 2SO at 90° do not break down hydroperoxide.

Decomposition of Hydroperoxides with Bis (O, O-diisobutylthiophosphoryl) disufide

Decomposition of cumyl hydroperoxide and t-butyl hydroperoxide with bis (O, O-diisobutylthiophosphoryl) disulfide (the isobutyl disulfide) consisted of a radical decomposition at the initial stage and an ionic decomposition at the later stage. After the complete decomposition of t-butyl hydroperoxide with the isobutyl disulfide, the reaction solution was separated into several components, and some of components derived from the isobutyl disulfide was identified and used for decomposition of t-butyl hydroperoxide as catalyst. It was found that sulfuric acid was most effective for the ionic decomposition. The formation mechanism of sulfuric acid was also proposed.

Contribution to the kinetics of induced decomposition of cumyl hydroperoxide

A quantitative analysis of the products of cumyl hydroperoxide decomposition (thermal and redox) in heptane and benzene in the temperature range of 30–155°C is used to study the kinetics of the induced reaction due to the abstraction of hydroperoxy hydrogen atoms by cumyloxy radicals.