- Semiconductor-photocatalyzed sulfoxidation of alkanes
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(Equation Presented) The C-H activation of alkanes with visible light is possible with a semiconductor as the photocatalyst. Upon irradiation, a mixture of titanium dioxide, sulfur dioxide, and oxygen can be used to convert alkanes into the corresponding sulfonic acids (see scheme).
- Parrino, Francesco,Ramakrishnan, Ayyappan,Kisch, Horst
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- Formation of the bisulfite anion (HSO3 -, m/z 81) upon collision-induced dissociation of anions derived from organic sulfonic acids
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In the negative-ion collision-induced dissociation mass spectra of most organic sulfonates, the base peak is observed at m/z 80 for the sulfur trioxide radical anion (SO3 -·). In contrast, the product-ion spectra of a few sulfonates, such as cysteic acid, aminomethanesulfonate, and 2-phenylethanesulfonate, show the base peak at m/z 81 for the bisulfite anion (HSO3 - ). An investigation with an extensive variety of sulfonates revealed that the presence of a hydrogen atom at the β-position relative to the sulfur atom is a prerequisite for the formation of the bisulfite anion. The formation of HSO3 - is highly favored when the atom at the β-position is nitrogen, or the leaving neutral species is a highly conjugated molecule such as styrene or acrylic acid. Deuterium-exchange experiments with aminomethanesulfonate demonstrated that the hydrogen for HSO3 - formation is transferred from the β-position. The presence of a peak at m/z 80 in the spectrum of 2-sulfoacetic acid, in contrast to a peak at m/z 81 in that of 3-sulfopropanoic acid, corroborated the proposed hydrogen transfer mechanism. For diacidic compounds, such as 4-sulfobutanoic acid and cysteic acid, the m/z 81 ion can be formed by an alternative mechanism, in which the negative charge of the carboxylate moiety attacks the α-carbon relative to the sulfur atom. Experiments conducted with deuterium-exchanged and deuterium-labeled analogs of sulfocarboxylic acids demonstrated that the formation of the bisulfite anion resulted either from a hydrogen transfer from the β-carbon, or from a direct attack by the carboxylate moiety on the α-carbon. Copyright
- Jariwala, Freneil B.,Wood, Ryan E.,Nishshanka, Upul,Attygalle, Athula B.
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experimental part
p. 529 - 538
(2012/08/28)
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- Foldamers as reactive sieves: Reactivity as a probe of conformational flexibility
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A series of m-phenyleneethynylene (mPE) oligomers modified with a dimethylaminopyridine (DMAP) unit were treated with methyl sulfonates of varying sizes and shapes, and the relative reactivities were measured by UV spectrophotometry. Using a small-molecule DMAP analogue as a reference, each of the methyl sulfonates was shown to react at nearly identical rate. In great contrast, oligomers that are long enough to fold, and hence capable of binding the methyl sulfonate, experience rate enhancements of 18-1600-fold relative to that of the small-molecule analogue, depending on the type of alkyl chain attached to the guest. Three different oligomer lengths were studied, with the longest oligomers exhibiting the fastest rate and greatest substrate specificity. Even large, bulky guests show slightly enhanced methylation rates compared to that with the reference DMAP, which suggests a dynamic nature to the oligomer's binding cavity. Several mechanistic models to describe this behavior are discussed.
- Smaldone, Ronald A.,Moore, Jeffrey S.
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p. 5444 - 5450
(2008/02/04)
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- Mercury-Photosensitized Sulfination, Hydrosulfination, and Carbonylation of Hydrocarbons: Alkane and Alkene Conversion to Sulfonic Acids, Ketones, and Aldehydes
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Mercury-photosensitized sulfination of alkanes, RH, with SO2 forms sulfinic acids (RSOOH) and sulfinate esters (RSOOR) in high conversion and yield; oxidation of the mixture produces RSO2OH in high yield.Mercury-photosensitized hydrosulfination of alkenes with H2 and SO2 gives RSO2OH after oxidative workup.Mercury-photosensitized carbonylation of alkanes with CO gives RCHO and R2CO.
- Ferguson, Richard R.,Crabtree, Robert H.
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p. 5503 - 5510
(2007/10/02)
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- 7-Oxabicycloheptane substituted prostaglandin interphenylene analogs useful in the treatment of thrombolytic disease
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7-Oxabicycloheptane substituted interphenylene prostaglandin ethers are provided having the structural formula STR1 and including all stereoisomers thereof. The compounds are cardiovascular agents useful, for example, in the treatment of thrombolytic disease.
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