Phthaloyl Peroxide Research Articles

Revealing the nature of covalently tethered distonic radical anions in the generation of heteroatom-centered radicals: evidence for the polarity-matching PCET pathway.

Recognition of the intermediacy and regulation of reactivity patterns of radical intermediates in radical chemistry have profound impacts on harnessing and developing the full potential of open-shell species in synthetic settings. In this work, the possibility of in situ formation of O/N-X intermediates from Brønsted base covalently tethered carbonyl hypohalites (BCTCs) for the generation of heteroatom-centered radicals has certainly been excluded by NMR experiments and density functional theory calculations. Instead, the spectroscopic analyses reveal that the BCTCs serve as precursors of tether-tunable distonic radical anions (TDRAs) which have been unequivocally substantiated to be involved in the direct cleavage of O/N-H bonds to generate the corresponding heteroatom-centered radicals. Meanwhile, a deep insight into the properties and reactivities of the resulting TDRAs indicates that the introduction of a tethered Brønsted base on the parent open-shell species reinforces their stabilities and leads to a reversal of electrophilicity. Moreover, the dual descriptor values and electrophilicity indices are calculated based on eleven reported radical reactions involving various electrophilic/nucleophilic radical species, further confirming their validity in the prediction of the polar effect and the polarity-matching consistency between nucleophilic TDRAs and protic O/N-H bonds. The additional halogen-free experiments mediated by the combination of phthaloyl peroxide and TEMPO also prove the feasibility of the TDRA-assisted philicity-regulation approach. Lastly, detailed intrinsic bond orbital (IBO) and Hirschfeld spin population analyses are employed to elucidate that the H-atom abstraction processes are the polarity-matching proton-coupled electron transfer (PCET) pathways, with a degree of oxidative asynchronicity.

An efficient synthesis of 2,3,5-trimethylbenzoquinone by metal-free oxidation of 1,2,4-trimethylbenzene

The oxidation of 1,2,4-trimethylbenzene with phthaloyl peroxide has been investigated under solvent-free and optimized conditions. 2,3,5-Trimethylbenzoquinone was obtained with great purity in 92% yield at 95% conversion of 1,2,4-trimethylbenzene at 120°C for 2.5 h under solvent-free conditions. The important factors such as the efficiency of the different cyclic acid anhydrides or carboxylic acid peroxides, the concentration of phthalic anhydride and 30% H2O2, the reaction time, the effect of solvent system, and the reaction temperature have been studied. An important advantage of this oxidizing system, aside from the organic solvent-free conditions, is that it is non-toxic, eco-friendly, and inexpensive. In addition, this methodology will be of great use in the preparation of commercially valuable benzoquinones from the corresponding aromatic compounds.

Electrochemical behavior of phthaloyl peroxide in aqueous media

The electrochemical behavior of phthaloyl peroxide C8H4O4 on an Au disk electrode in a 0.05 M aqueous solution of Na2SO4 was studied by cyclic voltammetry (CVA). It demonstrated a high activity in cathodic reduction with the formation of an irreversible peak on the CVA curve at E =–0.81 V. Additionally, during the anodic oxidation of C8H4O4, the surface of the Au electrode became passivated by compounds which prevented its oxidation during the registration of repeated cycles. Apparently, these compounds are surface complexes of phthaloyl peroxide with a gold cation.

ChemInform Abstract: [3 + 2] Cycloadditions of Azides with Arynes via Photolysis of Phthaloyl Peroxide Derivatives.

AbstractCycloaddition of photo‐generated benzynes with azides affords benzotriazoles in moderate to good yields at room temperature.

Dearomatization Reactions Using Phthaloyl Peroxide.

A new oxidative dearomatization reaction has been developed using phthaloyl peroxide to chemoselectively install two oxygen-carbon bonds into aromatic precursors. The oxidation reaction proceeds only once; addition of superstoichiometric equivalents of phthaloyl peroxide does not react further with the newly generated 1,3-cyclohexadiene. The reaction has been challenged by the addition of different functional groups and shown to maintain chemoselectivity. Due to the broad reactivity with 1,2-methylenedioxybenzene derivatives, linear free energy correlations were determined and support a mechanism proceeding through diradicals analogous to arene-hydroxylation reactions using phthaloyl peroxide.

Computational and Experimental Studies of Phthaloyl Peroxide-Mediated Hydroxylation of Arenes Yield a More Reactive Derivative, 4,5-Dichlorophthaloyl Peroxide.

The oxidation of arenes by the reagent phthaloyl peroxide provides a new method for the synthesis of phenols. A new, more reactive arene oxidizing reagent, 4,5-dichlorophthaloyl peroxide, computationally predicted and experimentally determined to possess enhanced reactivity, has expanded the scope of the reaction while maintaining a high level of tolerance for diverse functional groups. The reaction proceeds through a novel "reverse-rebound" mechanism with diradical intermediates. Mechanistic insight was achieved through isolation and characterization of minor byproducts, determination of linear free energy correlations, and computational analysis of substituent effects of arenes, each of which provided additional support for the reaction proceeding through the diradical pathway.

3 + 2] Cycloadditions of Azides with Arynes via Photolysis of Phthaloyl Peroxide Derivatives.

Photolysis of phthaloyl peroxides yields arynes, which undergo [3 + 2] cycloadditions with azides. This reaction tolerates a variety of organic azides and phthaloyl peroxides and affords the corresponding benzotriazoles in moderate to good yields at room temperature.

ChemInform Abstract: A Protocol to Generate Phthaloyl Peroxide in Flow for the Hydroxylation of Arenes.

AbstractPhthaloyl peroxide can be cleanly generated from phthaloyl chloride and sodium carbonate under continuous flow conditions.

Preparation of phenols by phthaloyl peroxide-mediated oxidation of arenes.

This protocol describes an approach to installing hydroxyls into arenes through the direct replacement of C-H bonds with C-O bonds. This direct oxidation avoids the need to prefunctionalize the substrate, use precious metals, introduce directing groups, or use strong Brønsted or Lewis acids. Phthaloyl peroxide, the sole reagent used for this transformation, can be prepared readily from the commodity chemicals phthaloyl chloride and sodium percarbonate. Phthaloyl peroxide oxidizes a diverse range of arenes, and the reactions that involve its use are characterized by high functional group compatibility, which enables the hydroxylation of simple arenes, advanced synthetic intermediates, natural products and other drug-like molecules forming the corresponding phenolic compounds. Notably, the reaction is operationally straightforward and has no special requirements for the exclusion of oxygen and water. The synthesis of phthaloyl peroxide takes 4 h and the subsequent hydroxylation of mesitylene takes 21 h.

A protocol to generate phthaloyl peroxide in flow for the hydroxylation of arenes.

A flow protocol for the generation of phthaloyl peroxide has been developed. This process directly yields phthaloyl peroxide in high purity (>95%) and can be used to bypass the need to isolate and recrystallize phthaloyl peroxide, improving upon earlier batch procedures. The flow protocol for the formation of phthaloyl peroxide can be combined with arene hydroxylation reactions and provides a method for the consumption of peroxide as it is generated to minimize the accumulation of large quantities of peroxide.

Metal-free oxidation of aromatic carbon–hydrogen bonds through a reverse-rebound mechanism

Methods for carbon-hydrogen (C-H) bond oxidation have a fundamental role in synthetic organic chemistry, providing functionality that is required in the final target molecule or facilitating subsequent chemical transformations. Several approaches to oxidizing aliphatic C-H bonds have been described, drastically simplifying the synthesis of complex molecules. However, the selective oxidation of aromatic C-H bonds under mild conditions, especially in the context of substituted arenes with diverse functional groups, remains a challenge. The direct hydroxylation of arenes was initially achieved through the use of strong Brønsted or Lewis acids to mediate electrophilic aromatic substitution reactions with super-stoichiometric equivalents of oxidants, significantly limiting the scope of the reaction. Because the products of these reactions are more reactive than the starting materials, over-oxidation is frequently a competitive process. Transition-metal-catalysed C-H oxidation of arenes with or without directing groups has been developed, improving on the acid-mediated process; however, precious metals are required. Here we demonstrate that phthaloyl peroxide functions as a selective oxidant for the transformation of arenes to phenols under mild conditions. Although the reaction proceeds through a radical mechanism, aromatic C-H bonds are selectively oxidized in preference to activated Csp3-H bonds. Notably, a wide array of functional groups are compatible with this reaction, and this method is therefore well suited for late-stage transformations of advanced synthetic intermediates. Quantum mechanical calculations indicate that this transformation proceeds through a novel addition-abstraction mechanism, a kind of 'reverse-rebound' mechanism as distinct from the common oxygen-rebound mechanism observed for metal-oxo oxidants. These calculations also identify the origins of the experimentally observed aryl selectivity.

Oxidative Addition of Phthaloyl Peroxide to Dimethylplatinum(II) Complexes

Complexes [PtMe2(NN)], with NN = 2,2′-bipyridine (bipy), 4,4′-di-tert-butyl-2,2′-bipyridine (bu2bipy), di-2-pyridylamine (dpa), or di-2-pyridyl ketone (dpk), react easily with phthaloyl peroxide to give a mixture of the chelate complex [PtMe2{κ2-O,O′-1,2-(O2C)2C6H4}(NN)], which was structurally characterized when NN = bu2bipy, and an oligomer or polymer [PtMe2{μ-κ2-O,O′-1,2-(O2C)2C6H4}(NN)]n. In the case with NN = dpa, no phthalate chelate complex is formed. These complexes are easily hydrolyzed, and the complexes cis-[PtMe2(OH){κ1-O-O2CC6H4-2-CO2H}(bipy)] and trans-[PtMe2{κ1-O-O2CC6H4-2-CO2H}(dpkOH)] have been structurally characterized. It is argued that the oxidative addition of phthaloyl peroxide occurs by a polar mechanism and that the hydrolysis is easy because there is no special stability associated with the seven-membered platinum-phthalate chelate ring.

ChemInform Abstract: Synthesis and Reaction of Phthaloyl Peroxide Derivatives, Potential Organocatalysts for the Stereospecific Dihydroxylation of Alkenes.

AbstractThe novel dichloro‐substituted peroxide (IV) displays improved stability comparable to the parent phthaloyl peroxide (IIa) while possessing higher reactivity.

Synthesis and reaction of phthaloyl peroxide derivatives, potential organocatalysts for the stereospecific dihydroxylation of alkenes

To improve the synthesis and reactivity of phthaloyl peroxide derivatives a method has been developed using sodium percarbonate and phthaloyl chlorides. The reactions of the new phthaloyl peroxide derivatives with trans-stillbene as well as the improved reactivity of 3,4-dichlorophthaloyl peroxide with a variety of alkenes are reported.

Reaction of Single-Walled Carbon Nanotubes with Organic Peroxides

Single-walled carbon nanotubes (SWNTs) induce the decomposition of four diacyl peroxides by single electron transfer (SET). Phthaloyl peroxide functionalizes SWNTs to the greatest extent of the four. It was also found that t-butoxy radicals add to SWNTs but that SWNTs fail to inhibit cumene autoxidation. Thus, SWNTs are reactive to alkoxy radicals but not to alkylperoxy radicals.

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.

New results of the free radical ring‐opening polymerization

AbstractThe reaction of 5‐ring ketene‐O, N‐acetals with peroxides was investigated. It was shown that benzoyl peroxide adds to monomers 5a and 5b by ring opening, giving the corresponding linear diester amides 6a and 6b, respectively. The ketene‐O,N‐acetal 5c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group, giving the cyclic‐O,N‐acetal diester 6c. With phthaloyl peroxide cyclic esteramides 7 and oligomeric products are formed. The chemical structures of the addition products were confirmed by NMR spectra and elemental analysis. © 1994 John Wiley & Sons, Inc.

ChemInform Abstract: ELECTRON‐TRANSFER‐INITIATED REACTIONS OF ORGANIC PEROXIDES. REACTION OF PHTHALOYL PEROXIDE WITH OLEFINS AND OTHER ELECTRON DONORS

Chemischer InformationsdienstVolume 11, Issue 44 Preparative Organic Chemistry ChemInform Abstract: ELECTRON-TRANSFER-INITIATED REACTIONS OF ORGANIC PEROXIDES. REACTION OF PHTHALOYL PEROXIDE WITH OLEFINS AND OTHER ELECTRON DONORS J. J. ZUPANCIC, J. J. ZUPANCICSearch for more papers by this authorK. A. HORN, K. A. HORNSearch for more papers by this authorG. B. SCHUSTER, G. B. SCHUSTERSearch for more papers by this author J. J. ZUPANCIC, J. J. ZUPANCICSearch for more papers by this authorK. A. HORN, K. A. HORNSearch for more papers by this authorG. B. SCHUSTER, G. B. SCHUSTERSearch for more papers by this author First published: November 4, 1980 https://doi.org/10.1002/chin.198044126Read the full textAboutPDF 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. Volume11, Issue44November 4, 1980 RelatedInformation

Electron-transfer-initiated reactions of organic peroxides. Reaction of phthaloyl peroxide with olefins and other electron donors

Abstract : The reaction of phthaloyl with a variety of compounds capable of reacting as one or two electron donors was investigated. The products and the kinetics of these reactions indicate that the rate-limiting step is the transfer of one electron from the reactant to the peroxide. This conclusion was substantiated by investigating these reactions by laser flash photolysis. This study showed conclusively that odd electron intermediates are formed in the reaction of phthaloyl peroxide with ground and excited state electron donors. These reactions may be prototypical of a general class of transfer initiated transformations. (Author)

The reaction of aldrin, photoaldrin and isodrin with phthaloyl peroxide

The reactions of aldrin and photoaldrin with phthaloyl peroxide in carbon tetrachloride provided the respective carbon tetrachloride adducts, epoxides and cyclic phthalates of the corresponding cis-diols. Under the same conditions isodrin yielded the half-cage ketone ( 14), the cyclic phthalate ( 17) and the novel half-cage adduct ( 15).