Decomposition Of Diacyl Peroxides Research Articles

N-Heterocycle-Forming Amino/Carboperfluoroalkylations of Aminoalkenes by Using Perfluoro Acid Anhydrides: Mechanistic Studies and Applications Directed Toward Perfluoroalkylated Compound Libraries.

This work describes a practical and efficient method for synthesizing a diverse array of perfluoroalkylated amines, including N-heterocycles, to afford perfluoroalkylated chemical libraries as potential sources of drug candidates, agrochemicals, and probe molecules for chemical-biology research. Perfluoro acid anhydrides, which are commonly used in organic synthesis, were employed as a perfluoroalkyl source for intramolecular amino- and carbo-perfluoroalkylations of aminoalkenes, affording perfluoroalkylated N-heterocycles, including: aziridines, pyrrolidines, benzothiazinane dioxides, indolines, and hydroisoquinolinones. Diacyl peroxides were generated in situ from the perfluoro acid anhydrides with urea·H2O2, and allowed to react with aminoalkenes in the presence of copper catalyst to control the product selectivity between amino- and carbo-perfluoroalkylations. To illustrate the synthetic utility of bench-stable trifluoromethylated aziridine, which was prepared on a gram scale, we used it to synthesize a wide variety of trifluoromethylated amines including complex molecules, such as trifluoromethylated tetrahydroharmine and spiroindolone. A mechanistic study of the role of the copper catalyst in the aminotrifluoromethylation of allylamine suggested that Cu(I) accelerates CF3 radical formation via decomposition of diacyl peroxide, which appears to be the turnover-limiting step, while Cu(II) controls the product selectivity.

Factors Determining the Catalytic Activity of Multi-walled Carbon Nanotubes in the Decomposition of Diacyl Peroxides in Non-aqueous Media (DPDec)

The catalytic activity of multi-walled carbon nanotubes (CNT) with different surface chemistry was investigated in the decomposition of benzoyl and lauroyl peroxides (BP and LP respectively) at room temperature in non-aqueous media. Calculated diffusion coefficients (D eff ) indicate that catalysis is not limited by internal diffusion. CNT demonstrate a moderate catalytic activity that ordering in the raw: N-CNT > CNTini > CNTox. Surface chemistry analysis displays the dependence of catalytic ability of CNT on their surface electron donor properties. Operation stability experiments and TPD–MS analysis reveal that reactions proceeding via the single electron transfer (SET) mechanism.

Curing reaction of unsaturated (epoxy) polyesters based on different aliphatic glycols

The cure behavior of the unsaturated (epoxy) polyesters based on different aliphatic glycols with styrene initiated by various types of organic peroxides or the mixture of an acid anhydride/organic peroxide has been studied by means of differential scanning calorimetry. unsaturated polyesters (UP) prepared from cyclohex-4-ene-1,2-dicarboxylic anhydride, maleic anhydride, and suitable aliphatic glycol: ethylene glycol or 1,4-butanediol or 1,6-hexanediol and unsaturated epoxy polyesters (UEP) obtained by chemical modification of UP were dissolved in vinyl monomer (styrene). The styrene solutions of polyesters were subjected to the cure reaction with suitable curing agent. The different organic peroxides: diacyl peroxide: benzoyl peroxide (BPO), dialkyl peroxide: dicumyl peroxide (DCP), and alkyl hydroperoxide: cumene hydroperoxide (CHP) were used. In addition, to cure the UEP, the mixture of the stoichiometric ratio of an acid anhydride (tetrahydrophthalic anhydride or hexahydrophthalic anhydride)/organic peroxide were applied. The curing characteristic such as: temperature of the cure initiation (Tonset), peak maximum temperature (Tmax), final cure temperature (Tend), the heat generated during the cure reaction (ΔH) were evaluated. It has been found that the course of the cure reaction of studied polyesters with styrene significantly depended on their structure and used initiating system. The presence of both carbon–carbon double bonds and epoxy groups in polyester backbone led to obtain more cross-linked materials where the copolymerization, thermal curing of epoxy groups with hydroxyl or carboxyl groups and polyaddition reaction of epoxy to anhydride groups have been expected. The use of BPO allowed to cure the polyesters at relatively lower temperatures with higher exothermic effect compared to DCP and CHP which was directly connected with lower thermal stability and significant higher ΔH values obtained during decomposition of diacyl peroxide used. In addition, the curing exotherm peak of polyesters based on glycol containing more –CH2– units with styrene was shifted to a bit higher temperatures which was probably due to lower molecular mobility of polyester’s chain caused the production of less stiff network structure.

Acyloxyl radical pair intermediate for the initial stage of the thermal decomposition of diacyl peroxide: a density functional study

To examine the reaction mechanism for the thermal reorganization, or more specifically the oxygen scrambling, in diacyl peroxide, we have carried out a hybrid density functional study using formyl peroxide as a model compound. The B3LYP calculations suggest that the oxygen scrambling in diacyl peroxide is most likely to occur via a σ-acyloxyl radical pair species: the competitive pathways of the [3,3]- and [1,3]-sigmatropic shifts are highly improbable. Thus, the mechanism for the thermal oxygen scrambling in diacyl peroxide should be completely different from those for the carbon counterparts of diacyl peroxide (the Cope and Claisen rearrangement).

The Kinetics and Selectivity of the Decomposition of Diacyl Peroxides Under High Pressure in Hydrocarbon Solution

Article The Kinetics and Selectivity of the Decomposition of Diacyl Peroxides Under High Pressure in Hydrocarbon Solution was published on January 1, 1996 in the journal Zeitschrift für Physikalische Chemie (volume 193, issue 1-2).

Thermal decomposition of diacyl peroxide. Part 11. 18O-Scrambling in carbonyl-18O-labelled phthaloyl peroxide, a cyclic Case III diacyl peroxide. Extremely large return of unescapable acyloxyl radical pair

18 O-Scrambling in carbonyl-18O-labelled phthaloyl peroxide, a cyclic Case III diacyl peroxide, proceeds 42 times faster than its decomposition at 80° C. This is the only diacyl peroxide for which 18O-scrambling takes place faster than the decomposition. The activation parameters have been found to be ΔdH‡= 33.4 ± 0.7 kcal mol–1 and ΔdS‡= 5.9 ± 1.9 cal mol–1 K–1 for decomposition and ΔsH‡= 31.9 ± 0.9 kcal mol–1 and ΔsS‡= 9.5 ± 2.6 cal mol–1 K–1 for 18O-scrambling. The results are best explained in terms of 97.6% of return of the phthaloyloxyl radical intermediate which is generated by homolysis of the O–O bond of the peroxide affording the 18O-scrambled peroxide. Based on this mechanism, the transition state for degradation of the phthaloyloxyl radical intermediate is estimated to be 1.5 kcal mol–1 greater than the recombination. Comparison of the kinetic data for phthaloyl peroxide with those for benzoyl peroxide reported by Martin and Hargis reveals that the extreme thermal stability of phthaloyl peroxide is not due to its cyclic structure which may hinder the O–O stretching vibration, but attributed to the facile phthaloyloxyl radical return. These observations clearly support our postulate concerning the structural effect on the 18O-scrambling of diacyl peroxide which indicates that the recombination of the aroyloxyl radical pair has to overcome a substantial activation energy barrier while a very small activation energy is necessary for aliphatic ones. The present kinetic data are discussed in comparison with those for the Cope rearrangement of 1,4-bis(dideuteriomethylidene)cyclohexane.

Thermal decomposition of diacyl peroxide. Part 10. Evidence for acyloxyl radical pair mechanism for 18O-scrambling of 18O-labelled cyclopropanecarbonyl peroxide

Oxygen-18 scrambling in carbonyl-18O-labelled cyclopropanecarbonyl peroxide (CPO) and benzoyl cyclopropanecarbonyl peroxide has been suggested to take place via the recombination of intimate acyloxyl radical pair, based on the following experimental observations. (i) The rate of thermal decomposition of CPO decreased with the increase in the viscosity of hydrocarbon solvent; however, the rate of the 18O-scrambling of CPO in Nujol, a highly viscous solvent, was found to be twice that in hexane. Examination of the effect of solvent viscosity on the rate of the decomposition of CPO by Pryor–Neuman's equation reveals that the 18O-scrambling in CPO takes place almost solely through recombination of the intimate cyclopropanecarboxyl radical pair. In octane, the rate constant for dissociation of the intimate cyclopropanecarboxyl radical pair was estimated to be one order of magnitude greater than those for recombination and decarboxylation of the intimate acyloxyl radical pair. (ii) The enthalpy of activation for the decomposition of CPO was found to be 2.0–2.8 kcal mol–1 greater than that for the 18O-scrambling of CPO in CCl4 which corresponds to the energy barrier for dissociation of the intimate cyclopropanecarboxyl radical pair in the solvent cage. The entropy of activation for 18O-scrambling was found to be small but positive in contrast to the large negative values of entropies of activation for usual concerted sigmatropic rearrangements. (iii) Successive substitution of the cyclopropyl groups of CPO with phenyl groups reduced markedly the rate of the 18O-scrambling in the peroxides. This substituent effect is the same as that in the initial bond breaking type of the Cope rearrangement of homotropylidenes; however, opposite to that is the Cope rearrangements of open chain hexa-1,5-dienes in which a substantial extent of the new bond has been formed in the transition state.

Evidence for electron transfer, radical and ionic pathways in the decomposition of diacyl peroxide

The thermal decomposition mechanism of 4,4-dimethylpentanoyl m-chlorobenzoyl peroxide and its α- and β-dideuteriated analogues is described. Product analyses and CIDNP studies suggest that all three pathways, electron transfer, radical and ionic, are operative in decomposition of these peroxides. Two pulsed-NMR techniques have been employed to eliminate distortions of CIDNP intensities arising from spin–lattice relaxation. These quantitative CIDNP studies have revealed an additional pure ionic pathway which competes with the radical pair electron transfer pathway to form rearranged reaction products.

Thermal decomposition of diacyl peroxides and peresters: An undergraduate laboratory experiment using infrared absorptions to monitor decomposition rates

This paper describes a technique that addresses the important educational goal of adapting research techniques into the teaching laboratory.

ChemInform Abstract: Decomposition of Diacyl Peroxides. Part 9. Mechanism of the Carboxy‐Inversion Process in the Thermal Decomposition of Benzoyl Cyclohexanecarbonyl Peroxide and Related Diacyl Peroxides.

AbstractThis is studied by a range of 18O‐tracer experiments under a variety of conditions with peroxides such as (I), especially (Ia).

Decomposition of diacyl peroxides. Part 9. Mechanism of the carboxy-inversion process in the thermal decomposition of benzoyl cyclohexanecarbonyl peroxide and related diacyl peroxides

Mechanisms of the carboxy-inversion process in the thermal decomposition of benzoyl cyclohexanecarbonyl peroxide and related diacyl peroxides have been investigated in detail by elabolate 18O-tracer experiments which involve measurements of 18O-scrambling of benzoyl cyclohexyl carbonate resulting from the initial carboxy-inversion process under the reaction conditions. A detailed analysis of the 18O-tracer experimental results reveals that the carboxy-inversion process of Case I and II peroxides involves three kinds of ion pairs. The extents of the contribution of these ion pairs in the carboxy-inversion process of benzoyl cyclohexanecarbonyl, peroxide and m-chlorobenzoyl cyclohexanecarbonyl peroxide have been determined. Details of the mechanisms of the thermal decomposition of diacyl peroxides have been discussed based on the 18O-tracer, kinetic, product-distribution and CIDNP experimental results and solvent effects on the decomposition.

Studies on the kinetics of decomposition of diacyl peroxides: VI. CIDNP in the products of thermolysis of lauroyl peroxide and 3,5,5-trimethylhexanoyl peroxide

The 1H NMR spectra recorded during the thermolysis of lauroyl peroxide and of 3,5,5-trimethylhexanoyl peroxide in ODCB containing 2-iodopropane show CIDNP multiplet effect. It was observed that the relative concentrations of 1-iodoundecane and 2-iodopropane, both polarized and normal species, changed with time. The relaxation time T1 of the α-protons in 1-iodoundecane and vinyl protons of CH2 in 1-undecene, enhancement factor of the protons of polarized species and the rate constant of decomposition for lauroyl peroxide have been determined. The mechanism of the decomposition of the entitled peroxides is discussed in terms of the radical pair theory.

Decomposition of diacyl peroxides in HMPA - An electron transfer process

In hexamethylphosphoric triamide (HMPA), four representative diacyl peroxides, namely, benzoyl peroxide (1), Cyclopropylformyl peroxide (2), lauroyl peroxide (3) and trifluoroacetyl peroxide (4), all decompose at rates much higher than those expected from their unimolecular thermal decomposition, and the corresponding carboxylic acids are formed in high yields (74–97%). Furthermore, several radical colligation products formed from HMPA molecules can be identified. Evidently, the initial step in the reaction between a diacyl peroxide and the “solvent” HMPA involves an electron transfer with the latter acting as the donor.

Studies on the kinetics of decomposition of diacyl peroxides: III. Kinetics and mechanism of decomposition of 3, 5, 5-trimethylhexanoyl peroxide in benzene

The kinetics of decomposition of 3,5,5-trimethylhexanoyl peroxide (1) in benzene at 30, 40, and 50°C respectively have been studied and the cage effect, main products and the products obtained in scavenging experiment with galvinoxyl determined and characterized. The results show that the decomposition of 1, with initial concentration between 0.04 to 0.43 mol. L−1, followed first plus three halves order kinetics with cage effect of 0.6, and the mechanism of decomposition is basically the same as previously proposed for lauroyl peroxide (2).4 In comparison with 2, the decomposition of 1 at the same temperature showed a faster rate for spontaneous decomposition, a larger cage effect and lesser induced decomposition, which is attributed to the branching in molecule of 1, especially to the presence of β-methyl group, which caused a larger entropy increase between the peroxide molecule and the transition state for decomposition.

Kinetics of thermal decomposition of diacyl peroxides in the presence of aerosil

In the presence of aerosil the thermal decomposition of the polymeric peroxide of sebacic acid is enhanced proportionally to the filler weight fraction in the reaction system. This is attributed to the interaction of peroxide groups with acidic groups on the aerosil surface and their decomposition according to a nonradical mechanism unlike the homolytic radical decomposition in solution.

The surface of silica as a medium for the radical and ionic decomposition of diacyl peroxides

The surface of silica as a medium for the radical and ionic decomposition of diacyl peroxides

Stereochemistry of nucleophilic solvent participation in the decomposition of diacyl peroxides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of nucleophilic solvent participation in the decomposition of diacyl peroxidesCheves Walling and John P. SloanCite this: J. Am. Chem. Soc. 1979, 101, 26, 7679–7683Publication Date (Print):December 1, 1979Publication History Published online1 May 2002Published inissue 1 December 1979https://doi.org/10.1021/ja00520a009RIGHTS & PERMISSIONSArticle Views80Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (608 KB) Get e-Alerts Get e-Alerts

Radical and ionic reaction pathways in the thermal decomposition of diacyl peroxides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRadical and ionic reaction pathways in the thermal decomposition of diacyl peroxidesK. Grant Taylor, C. K. Govindan, and Milton S. KaelinCite this: J. Am. Chem. Soc. 1979, 101, 8, 2091–2099Publication Date (Print):April 1, 1979Publication History Published online1 May 2002Published inissue 1 April 1979https://doi.org/10.1021/ja00502a026RIGHTS & PERMISSIONSArticle Views123Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

The Infrared Spectra of Alkyl Radicals: The Low Temperature Photochemical Decomposition of Diacyl Peroxides

The Infrared Spectra of Alkyl Radicals: The Low Temperature Photochemical Decomposition of Diacyl Peroxides

Decomposition of diacyl peroxide—VII : Oxygen scrambling in 1-apocamphoryl peroxide and related diacyl peroxides-general remarks on the relationship between the stability of acyloxy radical and amounts of cage recombinations and ester formation in the decomposition of diacyl peroxide

Thermal decomposition of 1-apocamphoryl peroxide has been investigated in CCl 4 using the 18O-labelled peroxide. 1-Apocamphoryl peroxide is the first example which undergoes radical decomposition, carboxy-inversion and oxygen scrambling reaction between carbonyl and peroxidic O atoms in the peroxide in comparable rates. The major product of the decomposition was the inversion product, 1-apocamphoryl 1-apocamphyl carbonate (52·5%), and only a minute amount of 1-apocamphyl 1-apocamphorate (2·2%) was formed. The rates of oxygen scrambling were found to be 2·70±0·21 × 10 −6 (55°), 1·85±0·12 × 10 −1 sec −1 (70°) and 9·33±0·18 × 10 −5 sec −1 (84·3°) (E a, 27·5 Kcal/mol, ΔS‡, −2·3 e.u.). The cage recombination mechanism was suggested for the oxygen scrambling and the amounts of cage recombination of 1-apocamphoryloxy radical pair were calculated as 65% (55°), 60% (70°) and 52% (84·3°). The yield of the ester and the amount of cage recombination of geminate acyloxy radical pair were rationalized in terms of the stability of acyloxy radicals formed in the cage.