Photo-Fries Rearrangement of Aromatic Esters. Role of Steric and Electronic Factors

Coppinger, Galvin M.; Bell, E. R.

doi:10.1021/j100883a018

Cited by 53 publications

(8 citation statements)

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“…The intramolecular rearrangement, proposed to involve a radical pair enclosed in a solvent cage, which produced the o-and p-hvdroxyphenylacetic acids during irradiation of 4-CPA in ethanoi at 254 nm (Kelly and Pinhev, 1964; Kelly et ai, 1969) was not observed in our experiments (300-450 nm in aqueous solutions), perhaps due to the presence of oxygen. An ionic process also has been suggested for the rearrangement (Coppinger and Bell, 1966) but was not in evidence.…”

Section: Resultsmentioning

confidence: 94%

Photodecomposition of p-chlorophenoxyacetic acid

Crosby¹,

Wong²

1973

J. Agric. Food Chem.

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Section: Resultsmentioning

confidence: 94%

Photodecomposition of p-chlorophenoxyacetic acid

Crosby¹,

Wong²

1973

J. Agric. Food Chem.

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“…The same behavior is shown by systems (3) and (4). It is interesting to note that the last two polymers show a large Δn at constant density, even if for system (5) it is smaller than the experimental value. What we can conclude is that the modulation of molecular polarizability alone is not enough to explain the experimental modulation of the refractive index, but a change in polymer density must occur.…”

Section: Resultsmentioning

confidence: 81%

“…For molecules (2)-(4), the change in polarizability is quite small and it is positive or negative according to the molecule and equilibrium geometry. Much larger are the changes for molecule (5) and (6), especially for the para product. This is due to the formation of a pushpull structure across the phenyl ring that enhances the polarizability.…”

Section: Resultsmentioning

confidence: 97%

Photosensitive polymers undergoing photo-Fries reaction for volume holography: understanding the mechanism of refractive index modulation

Bianco

Zanutta

Colella

et al. 2014

Practical Holography XXVIII: Materials and Applications

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Polymers that undergo to photo-Fries reaction show a remarkable modulation of the refractive index that makes them interesting in the field of volume holography. In order to understand the mechanism of the change in the refractive index we performed theoretical calculations (DFT) on model molecules. The results show that the modulation can be ascribed to a change in the polymer density upon photo-reaction whereas the contribution due to a change in molecular polarizability is small. The theoretical conclusions have been supported by experimental results on two polymers: Polyformyloxide styrene (PFS) and polyacetoxystyrene (PAS).

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“…In addition, the reaction quantum yield of rearranged products is strongly influenced by solvent polarity as well as by the presence of electron donor or acceptor in the aromatic moiety. 19,27,32,44,45 Scheme 1. General scheme of Photo-Fries rearrangement.…”

Section: Introductionmentioning

confidence: 99%

A three-state model for the photo-Fries rearrangement

Toldo

Barbatti

Gonçalves

2017

Phys. Chem. Chem. Phys.

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A three-state model for the photo-Fries rearrangement (PFR) is proposed based on multiconfigurational calculations. It provides a comprehensive mechanistic picture of all steps of the reaction, from the photoabsorption to the final tautomerization. The three states participating in the PFR are an aromatic ππ*, which absorbs the radiation; a pre-dissociativenπ*, which transfers the energy to the dissociative region; and a πσ*, along which dissociation occurs. The transfer fromππ* to nπ* involves pyramidalization of the carbonyl carbon, while transfer fromnπ* to πσ* takes place through CO stretching. Different products are available after a conical intersection with the ground state. Among them is a recombined radical intermediate, which can yield ortho-PFR products after an intramolecular 1,3-H tunneling. The three-state model is developed for phenyl acetate, the basic prototype for the PFR, and it reconciles the theory with a series of observations from time-resolved spectroscopy. It also delivers a rational way to optimize PFR yields, since, as shown for four different systems, diverse substituents can change the energetic order of theππ* and nπ* states, preventing or enhancing the PFR.

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Photo-Fries Rearrangement of Aromatic Esters. Role of Steric and Electronic Factors

Cited by 53 publications

References 0 publications

Photodecomposition of p-chlorophenoxyacetic acid

Photodecomposition of p-chlorophenoxyacetic acid

Photosensitive polymers undergoing photo-Fries reaction for volume holography: understanding the mechanism of refractive index modulation

A three-state model for the photo-Fries rearrangement

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