Photochemical studies, VII. Solvent effects on the photolysis of aryl esters: fries rearrangement decarboxylation

Finnegan, R.A.; Knutson, D.

doi:10.1016/s0040-4039(00)89510-6

Cited by 24 publications

(5 citation statements)

References 11 publications

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“…Solvent Effects on the Competition between Photodecarboxylation and Photo-Fries Processes. The distribution of photo-Fries products and the ratio of decarboxylation to Fries product yields are known to be solvent dependent. , Table summarizes the results from irradiations of 1 for 5 min at 0 °C (typically 10∼20% conversions) in a variety of solvents; reaction was performed at 10 °C in 1,4-dioxane because of its melting point. As reported previously, , the photoproduct distributions from aryl esters can depend on the method that some solvents are purified.…”

Section: Resultsmentioning

confidence: 99%

Mediation of Conformationally Controlled Photodecarboxylations of Chiral and Cyclic Aryl Esters by Substrate Structure, Temperature, Pressure, and Medium Constraints

2004

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An aryl alkanoate, 2,4,6-trimethylphenyl (S)-(+)-2-methylbutyrate, whose ester group has a chiral center alpha to the carbonyl carbon and in which photo-Fries rearrangements are blocked by methyl substituents, undergoes facile photodecarboxylation under a variety of conditions and with complete retention of configuration. In fact, the decarboxylation process has many of the attributes of a symmetry-allowed suprafacial [1,3]sigmatropic rearrangement. The process requires concerted extrusion of carbon dioxide in a spiro-lactonic transition state, which has been investigated using high level DFT and CIS calculations: thermally less stable s-cis conformers in the ground and excited singlet states play an important role in determining the competitive efficiency of the process. Conformational control has also been imposed by substrate structure, solvent interactions, temperature, and applying external pressure, as well as using constraining media such as cyclodextrins and polyethylene films. The results are correlated with steady-state and dynamic fluorescence measurements at various temperatures in order to investigate further degrees to which ground and excited singlet state conformations affect the different photoreactivity channels available to the aryl esters.

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Section: Resultsmentioning

confidence: 99%

Mediation of Conformationally Controlled Photodecarboxylations of Chiral and Cyclic Aryl Esters by Substrate Structure, Temperature, Pressure, and Medium Constraints

2004

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“…Decarboxylation was first observed by Finnegan and Knudsen. [5] This reaction also proceeds from the excited S 1 state and transforms the aromatic ester R-COO-R 0 into a hydrocarbon R-R 0 . For this photoextrusion of CO 2 a concerted mechanism has been proposed.…”

Section: Full Papermentioning

confidence: 99%

Selected Polymers that Contain Aromatic Ester Units: Synthesis, Photoreactions, and Refractive Index Modulation

Daschiel

Höfler

Jakopič

et al. 2007

Macro Chemistry & Physics

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Photoreactive polymers bearing aliphatic and aromatic esters of 4‐(N,N‐diphenylamino)phenol in the side chain, poly[4‐(N,N‐diphenylamino)phenyl acrylate] (P1) and poly[4‐(N,N‐diphenylamino)phenyl 4‐vinylbenzoate] (P2), are prepared from their monomers by free radical polymerization. In addition, poly[naphthalene‐1‐yl 4‐vinylbenzoate] is synthesized (P3). These materials absorb UV light up to λ = 350 nm. The polymers P1–P3 as well as low‐molecular‐weight model compounds are investigated with respect to their photoreactions under UV illumination. It is found that decarboxylation is the dominant reaction and that the photo‐Fries rearrangement occurs as a minor reaction. The fully aromatic ester units in P2 are more reactive than the ester units in P1. In the polymers, decarboxylation proceeds more efficiently than in the low‐molecular‐weight model compounds. Upon UV illumination of the polymers, large increases of the refractive index are observed (Δn450 up to +0.07). This is in agreement with the structural changes in the polymers after irradiation as calculated from group contributions to molar refraction. A preliminary investigation under 610 nm fs laser irradiation indicates that refractive index patterns can be produced by two‐photon effects (TPA). The polymers are of potential interest for applications in the field of optical waveguides.magnified image

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“…Decarboxylation was first observed by Finnegan and Knudsen. [5] Also this reaction proceeds from the excited S 1 state and transforms the aromatic ester R-COO-R' into a hydrocarbon R-R'. For this photoextrusion of CO 2 a concerted mechanism has been proposed.…”

Section: Introductionmentioning

confidence: 99%

Index patterning of photoreactive polymers

et al. 2009

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Photoreactive polymeric materials have been investigated under one-photon (linear) and two photon (non linear) absorption conditions. A selected chromophore, 4-(N,N-diphenylamino)phenyl benzoate, was covalently attached to different polymer backbones (polystyrene, polynorbornene and polysiloxane). It is shown, that the predominant photoreaction of the chromophore is a photo-decarboxylation (extrusion of CO 2 ) both for two-photon and one-photon conditions. The large increase in refractive index, which results from this reaction, allows the optical patterning of the polymeric systems by conventional and two-photon radiation processes. The materials were investigated by ellipsometry, UV-VIS and FT-IR spectroscopy, FT-IR and phase contrast microscopy. Under two-photon conditions, threedimensional index structures were inscribed in the polymers, which can be used as optical waveguides.

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Photochemical studies, VII. Solvent effects on the photolysis of aryl esters: fries rearrangement decarboxylation

Cited by 24 publications

References 11 publications

Mediation of Conformationally Controlled Photodecarboxylations of Chiral and Cyclic Aryl Esters by Substrate Structure, Temperature, Pressure, and Medium Constraints

Mediation of Conformationally Controlled Photodecarboxylations of Chiral and Cyclic Aryl Esters by Substrate Structure, Temperature, Pressure, and Medium Constraints

Selected Polymers that Contain Aromatic Ester Units: Synthesis, Photoreactions, and Refractive Index Modulation

Index patterning of photoreactive polymers

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