Cationic and radical intermediates in the acid photorelease from aryl sulfonates and phosphates

Terpolilli, Marco; Merli, Daniele; Protti, Stefano; Dichiarante, Valentina; Fagnoni, Maurizio; Albini, Angelo

doi:10.1039/c0pp00284d

Cited by 31 publications

(36 citation statements)

References 44 publications

(23 reference statements)

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“…[12,13] We (and others) have found that inorganic esters (phosphates, sulfonates), of general formula ArÀOZ, operate as nucleofugal leaving groups in the place of chlorides (path a in Scheme 1 b), [4,14] in competition with ArOÀZ bond cleavage (path b in Scheme 1 b). [15] The easy availability of such compounds makes the choice appealing, although the scope is little known. As a contribution to the clarification of the matter, we decided to carry out a systematic study of some esters of (trimethylsilylmethyl)phenols, more precisely, mesylates (1 a-c), triflates (2 a-c), and diethylphosphates (3 a-c; Figure 1), and to supplement product studies with a computational investigation.…”

Section: Introductionmentioning

confidence: 99%

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Competing Pathways in the Photogeneration of Didehydrotoluenes from (Trimethylsilylmethyl)aryl Sulfonates and Phosphates

Crespi¹,

Ravelli²,

Protti³

et al. 2014

Chemistry A European J

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The scope of the photochemical generation of α,n-didehydrotoluene diradicals from aryl sulfonates and phosphates and their chemistry are explored. The thermally inaccessible α,2- and α,4- intermediates are efficiently obtained by irradiation of ortho- and para-(trimethylsilylmethyl)phenyl triflates through heterolytic splitting of the ester anion from the substrate in the triplet state. Triplet phenyl cations are formed and the loss of trimethylsilyl cation from them affords the desired diradicals ((3) Me3 SiCH2 C6 H4 -OZ→(3) Me3 SiCH2 C6 H4 (+) →(⋅) CH2 C6 H4 (⋅)). Triplet sensitization is required, for which acetone is used throughout. Direct irradiation leads, on the contrary, to photo-Fries fragmentation ((1) Me3 SiCH2 C6 H4 O-Z→Me3 SiCH2 C6 H4 O(⋅) +Z(⋅)). With mesylates, where ester cleavage is less convenient, a further competition from the triplet is direct desilylation. Didehydrotoluenes are also obtained from the corresponding phosphates, although with poor efficiency.

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Section: Introductionmentioning

confidence: 99%

“…Direct 4 b (27) 6 (6) 8 (4) Sens. [b] 4 b (tr) 6 (tr) 7'' (21), 7''' (15), 8 (51) 2 c Direct 4 c (8), 4'' (22) 6 (tr) Sens. [b] 6 (tr) 7'' (10), 7''' (15) 3 a Direct 7' (1), 7'' (9) Sens.…”

mentioning

confidence: 99%

Competing Pathways in the Photogeneration of Didehydrotoluenes from (Trimethylsilylmethyl)aryl Sulfonates and Phosphates

Crespi¹,

Ravelli²,

Protti³

et al. 2014

Chemistry A European J

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“…[33] Fagnoni et al [34] schlugen vor,d ass elektronenrei-che Arylsulfonate wie Mesylat-und Tr iflatderivate bevorzugt durch eine heterolytische Spaltung der Ar-O-Bindung unter Freisetzung des entsprechenden Ar + -Kations und Sulfonat-Anions photolytisch zersetzt werden. Einer der akzeptierten Mechanismen der Säurebildung besteht in der homolytischen Photospaltung der Ar-O-Bindung.…”

Section: Arylsulfonatesterunclassified

“…Tatsächlich wird weit mehr Nebenprodukt durch eine Photo-Fries-Umlagerung erzeugt, die aus der Kombination von Radikalen zur Bildung von Hydroxyphenylsulfon-Derivaten besteht. [33] Fagnoni et al [34] schlugen vor,d ass elektronenrei-…”

Section: Arylsulfonatesterunclassified

Organische Photosäuren‐ und Photobasenbildner für Polymerisationen: Jüngste Fortschritte und Herausforderungen

et al. 2019

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Photopolymerisation, oder in anderen Worten die Nutzung von Licht als Auslöser einer Polymerisationsreaktion, ist eine der vielversprechendsten Technologien zur Herstellung anspruchsvoller Polymere. Eine der Schlüsselkomponenten der Photopolymerisation ist die photoaktive Spezies. Diese ist in der Lage, durch die Absorption von Licht die aktive Verbindung zu generieren, welche die Polymerisation der Monomere einleitet und einen großen Einfluss auf die Eigenschaften des finalen Produkts hat. In der Vergangenheit war das Forschungsfeld der Photopolymerisation von photoaktiven Radikalbildnern zur Einleitung radikalischer Reaktionen dominiert. Um das Spektrum der Polymere, die durch eine Photopolymerisation hergestellt werden können zu erweitern, wurde im letzten Jahrzehnt intensive Forschungsarbeit zur Synthese und Verwendung photoaktiver Moleküle geleistet, die in der Lage sind, unter Einfluss von Licht Säuren oder Basen zu bilden. Diese Verbindungen sind nicht nur dafür bekannt, die ringöffnende Polymerisation verschiedenster heterozyklischer Monomere, wie Laktone, Carbonate oder Epoxide einzuleiten, sondern auch die Stufenwachstumsreaktion von Polyurethanen zu initiieren. Dieser Kurzaufsatz hebt die jüngsten Fortschritte zur Entwicklung organischer, photoaktiver Säuren‐ und Basenbildner hervor, mit dem Ziel, eine breitere Anwendung der photoaktiven Verbindung im Bereich der Photopolymerisation zu fördern und die Verwendung der daraus resultierenden Polymere für anspruchsvolle Produktionsprozesse zu ermöglichen.

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“…43) The heterolytic cleavage of an O-aryl bond from T 1 to form a σ aryl cation is likely, as reported for OP esters that have an electron-rich aromatic group. 189) …”

Section: Thiono-thiolo Rearrangementmentioning

confidence: 99%

Direct photolysis mechanism of pesticides in water

Katagi

2018

Journal of Pesticide Science

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Photodegradation is one of the most important abiotic transformations for pesticides in the aquatic environment, and the high energy of sunlight causes characteristic reactions such as bond scission, cyclization, and rearrangement, which are scarcely observed in hydrolysis and microbial degradation. This review deals with direct photolysis via excitation of a pesticide by absorbing natural or artificial sunlight in order to know its basic photochemistry, and indirect photolysis meaning either sensitization by dissolved organic matters or oxidation by reactive oxygen species is basically excluded. Several experimental approaches including spectroscopic techniques together with theoretical calculations are first discussed from the viewpoint of the reaction mechanisms in direct photolysis. Then, the typical photoreactions of pesticides are summarized by chemical classes and/or functional groups and discussed as far as possible in relation to their mechanisms.

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Cationic and radical intermediates in the acid photorelease from aryl sulfonates and phosphates

Cited by 31 publications

References 44 publications

Competing Pathways in the Photogeneration of Didehydrotoluenes from (Trimethylsilylmethyl)aryl Sulfonates and Phosphates

Competing Pathways in the Photogeneration of Didehydrotoluenes from (Trimethylsilylmethyl)aryl Sulfonates and Phosphates

Organische Photosäuren‐ und Photobasenbildner für Polymerisationen: Jüngste Fortschritte und Herausforderungen

Direct photolysis mechanism of pesticides in water

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