Solvent Sensitivity of Type Ii Photoreactions of Ketones as a Device to Probe Solute Location in Micelles

Turro, Nicholas J.; Liu, Kou-Chang; Chow, Ming‐Fea

doi:10.1111/j.1751-1097.1977.tb07507.x

Cited by 38 publications

(7 citation statements)

References 10 publications

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“…It is interesting to note that the lifetime measured in SDS compares well with those measured in methanol and in acetonitrile (20): we take this result to mean that the ketone triplet'resides in a very polar environment, probably with the carbonyl group in the Stern layer, as proposed by de Mayo and co-workers (6,7). It is interesting to note that earlier results, showing that the Norrish Type I1 process occurs with high quantum yields (10) and that the biradical has a relatively long lifetime (1 I), can only provide information on the location of the biradical, not the triplet state.…”

Section: Discussionsupporting

confidence: 55%

Dynamic aspects of the behavior of aromatic ketone triplets in anionic micelles. A laser flash photolysis study

Scaiano¹,

Selwyn²

1981

Can. J. Chem.

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The behavior of several aromatic ketone triplets has been examined in sodium dodecyl sulfate micelles using laser flash photolysis techniques. The molecules examined, acetophenone, propiophenone, isobutyrophenone, p-methoxyacetophenone, benzophenone, and xanthone are mainly resident in the micellar phase. Phenyl alkyl ketones show considerable self-quenching, a process that is rather sensitive to steric factors. All the molecules examined seem to reside near the Stern layer. Typical rate constants for triplet state entry into the micelle are around 1.8 × 1010 M−1 s−1.

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Section: Discussionsupporting

confidence: 55%

Dynamic aspects of the behavior of aromatic ketone triplets in anionic micelles. A laser flash photolysis study

Scaiano¹,

Selwyn²

1981

Can. J. Chem.

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“…Photoproduct studies of TPP sorbed on sediment were less rewarding. It was hoped to learn something about the microenvironment of sorbed TPP by examining the ratio of the two cyclobutanols (15,21); the trans to cis ratio is sensitive to changes in solvent. Unfortunately, the isomers could not be adequately resolved by gas chromatography.…”

Section: Fwsmentioning

confidence: 99%

Photoreactivity of aquatic pollutants sorbed on suspended sediments

Miller¹,

Zepp²

1979

Environ. Sci. Technol.

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A technique is described that can be used to ascertain the photoreactivity of chemicals sorbed on particulates suspended in water.. The influence of sorption on photoreactivity is disentangled from the effects of light attenuation and scattering by the sorbent. When this technique was employed, the photoreactivity of two hydrophobic chemicals was determined on sediments obtained from three widely separated water bodies in the United States. Kinetic and product studies indicate that the sorbed chemicals are in a less polar microenvironment that is a considerably better hydrogen atom donor than water.Organic pollutants from municipal, industrial, and agricultural sources are often found in sediment-laden streams and ponds ( I ) . In these waters, significant fractions of extremely hydrophobic pollutants are physically sorbed to the suspended sediments (2-4). Several studies have indicated that the photochemical behavior of chemicals in the sorbed state differs from that in the dissolved state (5, 6), but few studies have been conducted using commercially important chemicals or natural sediments. Bailey and Karickhoff ( 7 ) , however, found that the electronic absorption spectra and photochemistry of the pesticide paraquat and N-methylpyridinium cation were greatly altered by sorption on clays suspended in water. Carey and co-workers (8) observed that polychlorinated biphenyls were photodechlorinated rapidly when sorbed on suspended titanium dioxide in water. Polycyclic aromatic hydrocarbons are photoreactive when sorbed on garden soil (9) or on kaolinite or calcium carbonate suspended in water (10,11). Although these studies have provided interesting qualitative data concerning heterogeneous photolysis in water, no quantitative studies of these phenomena have been conducted.In an earlier paper (12), data were presented concerning the effects of natural sediments on photolysis rates of dissolved pollutants. The primary effect noted was a decrease in the photolysis rate caused by light attenuation by the sediment. Under certain conditions, however, the increased diffuseness of light that was caused by light scattering actually resulted in enhanced photolysis rates in clay suspensions. Effects of light attenuation and scattering must be taken into account to quantitatively determine the photoreactivity of a chemical that is sorbed in a heterogeneous system. The present work describes a procedure that was employed to ascertain the photoreactivity of two hydrophobic organic chemicals sorbed on natural sediments suspended in water. ExperimentalMaterials. Suspensions of sediments were obtained by resuspending bottom sediment from three natural sources in tap water. Because it was necessary to maintain stable suspensions over the course of the experiments, each sediment suspension was allowed to settle for 24 h and only the supernatant (top 10 cm) was used. According to Stokes law (13), this supernatant contained particles with diameters less than approximately 2 pm.y-Methoxy-m-trifluoromethylbutyrophenone (MTB) was synthe...

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“…The photolysis of valerophenone was suggested as a device to probe solute location in micelles (19). When valerophenone (0.01 M) was irradiated in an aqueous solution of MNP (1.5 mg/mL) containing hexadecyltrimethyl ammonium chloride (5 x M), two overlapping spectra were recorded.…”

Section: Photolyses Of Ualerophenonementioning

confidence: 99%

Spin-trapping with 2-methyl-2-nitrosopropane: photochemistry of carbonyl-containing compounds. Methyl radical formation from dimethyl sulfoxide

Rosenthal¹,

Mossoba²,

Riesz³

1982

Can. J. Chem.

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The photochemical reactions of several carbonyl-containing compounds investigated by spin-trapping with 2-methyl-2-nitrosopropane revealed different modes of scission depending on the structure of the initial compound. Thus, in photo-Fries rearrangements, the acyl radical was detected. 1,3-Diphenyl-2-propanone decarbonylated to yield the benzyl radical. Finally, valerophenone yielded the radicals expected by γ-hydrogen abstraction. In a dark reaction, dimethyl sulfoxide reacts with NaOH to generate methyl radicals. The latter result suggests the need for caution in the use of dimethyl sulfoxide with 2-methyl-2-nitrosopropane for the detection of hydroxyl radicals.

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Solvent Sensitivity of Type Ii Photoreactions of Ketones as a Device to Probe Solute Location in Micelles

Cited by 38 publications

References 10 publications

Dynamic aspects of the behavior of aromatic ketone triplets in anionic micelles. A laser flash photolysis study

Dynamic aspects of the behavior of aromatic ketone triplets in anionic micelles. A laser flash photolysis study

Photoreactivity of aquatic pollutants sorbed on suspended sediments

Spin-trapping with 2-methyl-2-nitrosopropane: photochemistry of carbonyl-containing compounds. Methyl radical formation from dimethyl sulfoxide

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