- Photoinduced Coupling Reaction of Diphenyl(2,4,6-trimethylbenzoyl)phosphine Oxide with Interelement Compounds: Application to the Synthesis of Thio- or Selenophosphinates
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Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TMDPO) is a radical initiator widely used in the field of macromolecular chemistry, but not often applied in synthetic organic chemistry. We have focused on the use of TMDPO as a phosphorus source in reactions with different E - E compounds, where E - E represents a heteroatom-heteroatom bond, under photoirradiation. Interestingly, the cross-coupling reaction between TMDPO and disulfides or diselenides successfully affords thio- or selenophosphinates and thio- or selenoesters, respectively. The synthesis of series of thio- and selenophosphinates by this photoinduced cross-coupling reaction is demonstrated.
- Sato, Yuki,Kawaguchi, Shin-Ichi,Nomoto, Akihiro,Ogawa, Akiya
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- Investigating the existence of nonthermal/specific microwave effects using silicon carbide heating elements as power modulators
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(Chemical Equation Presented) The use of passive heating elements made out of chemically inert sintered silicon carbide (SiC) allows microwave transparent or poorly absorbing reaction mixtures to be heated under microwave conditions. The cylindrical heating inserts efficiently absorb microwave energy and subsequently transfer the generated thermal energy via conduction phenomena to the reaction mixture. In the case of low to medium microwave absorbing reaction mixtures, the addition of SiC heating elements results in significant reductions (30-70%) in the required microwave power as compared to experiments performed without heating element at the same temperature. The method has been used to probe the influence of microwave power (electromagnetic field strength) on chemical reactions. Six diverse types of chemical transformations were performed in the presence or absence of a SiC heating element at the same reaction temperature but at different microwave power levels. In all six cases, the measured conversions/yields were similar regardless of whether a heating element was used or not. The applied microwave power had no influence on the reaction rate, and only the attained temperature governed the outcome of a specific chemical process under microwave conditions.
- Razzaq, Tahseen,Kremsner, Jennifer M.,Kappe, C. Oliver
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p. 6321 - 6329
(2008/12/22)
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- Scope and mechanistic insights into the use of tetradecyl(trihexyl) phosphonium bistriflimide: A remarkably selective ionic liquid solvent for substitution reactions
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A survey of substitution reactions conducted in a phosphonium bistriflimide ionic liquid is presented. The results demonstrate high selectivity favoring substitution over typically competitive elimination and solvolytic processes even when challenging secondary and tertiary electrophiles are employed. The first reports of Kornblum substitution reactions in an ionic liquid are described that proceed with very high chemoselectivity in favor of nitro over nitroso products and elimi nation side products. The structure-reactivity study indicates that these reactions proceed through a narrow spectrum of pathways ranging from straight SN2 to a preassociation pathway along a saddle point that approaches the SN1 limit. The barrier to the formation of dissociated carbocations is attributed to the structural features of this ionic liquid that favor intervention of the associated nucleophile over dissociation, also preventing cross over to E1 processes. The lack of any basic entity in the phosphonium bistriflimide ionic liquid appears to prevent any potential base-mediated elimination reactions, which makes this a highly selective medium for use in general substitution reactions.
- McNulty, James,Nair, Jerald J.,Cheekoori, Sreedhar,Larichev, Vladimir,Capretta, Alfredo,Robertson
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p. 9314 - 9322
(2007/10/03)
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- Efficient esterification of carboxylic acids and phosphonic acids with trialkyl orthoacetate in ionic liquid
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An operationally simple, inexpensive, efficient, and environmentally friendly esterification of various carboxylic acids, phosphonic acids, and phosphinic acids with triethyl orthoacetate or trimethyl orthoacetate under neutral conditions in a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, was successfully carried out to provide the corresponding ethyl esters or methyl esters in high yields.
- Yoshino, Tomonori,Imori, Satomi,Togo, Hideo
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p. 1309 - 1317
(2007/10/03)
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- A mild esterification process in phosphonium salt ionic liquid
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A general, high yielding procedure is described for the esterification of carboxylic acids through carboxylate alkylation in phosphonium salt ionic liquid.
- McNulty, James,Cheekoori, Sreedhar,Nair, Jerald J.,Larichev, Vladimir,Capretta, Alfredo,Robertson, Al J.
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p. 3641 - 3644
(2007/10/03)
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- Facile preparation of polymer-supported methyl sulfonate and its recyclable use for methylation of carboxylic acids and amines
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A simple and efficient one-pot procedure for the preparation of polymer-supported methyl sulfonate from the reaction of polymer-supported sulfonic acid with trimethyl orthoacetate was achieved, and it could be successfully used for efficient methylation of carboxylic acids, phosphonic acids, sulfinic acids, amines, thiol, and phenol. Moreover, the polymer reagent could be recovered, regenerated, and reused easily for the same reactions. Georg Thieme Verlag Stuttgart.
- Yoshino, Tomonori,Togo, Hideo
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p. 517 - 519
(2007/10/03)
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- Microwave promoted facile synthesis of methyl and ethyl carboxylates
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Microwave irradiation of carboxylic acids with trialkyl orthoacetate in solvent-free conditions afforded an efficient method for alkylation of carboxylic acids to corresponding alkyl carboxylates.
- Lee, Jong Chan,Song, In-Goul,Park, Jin Young
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p. 2209 - 2213
(2007/10/03)
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- Novel syntheses of symmetrical 2,5-diaryl-1,3,4-oxadiazoles and 1,4-phenylenebis-1,3,4-oxadiazoles
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The reactions of trichloromethylarenes with excess hydrazine hydrate in ethanol gives symmetrical 2,5-diaryl-1,3,4-oxadiazoles in 68-96% yields. The reaction of 1,4-bis(trichloromethyl)benzene with acylhydrazines in an ethanol-pyridine mixture gives the corresponding substituted or unsubstituted 1,4-phenylenebis-1,3,4-oxadiazoles in 35-51% yields. The mass spectra of 2,5-diaryl-1,3,4-oxadiazoles and 1,4-phenylenebis-1,3,4-oxadiazoles were studied.
- Belen'kii,Luiksaar,Poddubnyi,Krayushkin
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p. 2238 - 2245
(2007/10/03)
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- An improved method for preparation of carboxylic esters using CsF- celite/alkyl halide/CH3CN combination
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A new method for efficient and chemoselective esterification of carboxylic acids in CsF-Celite/alkyl halide/CH3CN reaction system is described.
- Lee, Jong Chan,Choi, Youngsup
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p. 2021 - 2026
(2007/10/03)
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- A HIGH YIELD ROUTE TO ETHYL ESTERS OF CARBOXYLIC ACIDS
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Diethyl trichloromethylphosphonate reacts with carboxylic acids to yield their ethyl esters, via transesterification; even the hindered mesitoic acid is esterified in high yield.
- Downie, Ian M.,Wynne, Neil,Harrison, Stephen
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p. 1457 - 1458
(2007/10/02)
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- Synthetic and Mechanistic Aspects of Gas-Liquid Phase-transfer Catalysis: Carboxylate Esters
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The synthesis of esters from solid alkyl- and aryl-carboxylates and gaseous alkyl halides (RX), that is gas-liquid phase-transfer catalysis (g.l.p.t.c.) is promoted by the classical phase-transfer catalysts, quaternary phosphonium salts.The reaction is run under continuous-flow conditions in a column and the product is collected at the outlet.An investigation of the mechanism of the reaction shows the great importance of the liquid film of melted catalyst in promoting anion exchange between the underlying solid carboxylate salt and the gaseous alkyl halide which diffuses and reacts.This technique does not require the use of organic or aqueous solvents, leads to high conversion into esters for low carboxylate: RX molar ratios, and transforms large quantities of reagents with small volumes of solid bed.
- Angeletti, Enrico,Tundo, Pietro,Venturello, Paolo
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p. 993 - 998
(2007/10/02)
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