- Switchable Synthesis of Arylalkynes and Phthalides via Controllable Palladium-Catalyzed Alkynylation and Alkynylation-Annulation of Benzoic Acids with Bromoalkynes
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A ligand-promoted palladium(II)-catalyzed synthesis of arylalkynes and phthalides from benzoic acids and bromoalkynes via carboxylate-assisted ortho-C-H activation is reported. A series of phthalides with various functional groups are prepared via ortho-a
- Shi, Shuai,Chen, Cui-Hong,Chai, Yun,Zhang, Li-Ting,Li, Jia-Wei,Liu, Bin,Liu, Yue-Jin,Zeng, Ming-Hua
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p. 9161 - 9168
(2019/08/12)
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- Electrochemical reduction of phthalide at carbon cathodes in dimethylformamide: Effects of supporting electrolyte and gas chromatographic injector-port chemistry on the product distribution
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Cyclic voltammetry and controlled-potential (bulk) electrolysis have been used to investigate the direct reduction of phthalide at carbon electrodes in dimethylformamide (DMF) containing 0.10 M tetramethylammonium perchlorate (TMAP) or tetra-n-butylammonium perchlorate (TBAP). Cyclic voltammograms recorded with a glassy carbon electrode exhibit a single cathodic peak and a corresponding anodic peak that arise, respectively, from one-electron reduction of phthalide to generate a radical-anion intermediate and from reoxidation of the intermediate. At a scan rate of 100 mV s-1, quasi-reversible behavior is observed (due to ring-opening of the radical-anion), whereas fully reversible behavior is seen at 5 V s-1 or higher. Digital simulation of cyclic voltammograms indicates that the lifetime of the radical-anion is 3.5 s. Bulk electrolysis of phthalide at a reticulated vitreous carbon cathode affords products that depend on the procedure used to analyze the catholyte. Direct injection of catholyte into a gas chromatograph shows phthalide and a 2-methylbenzoate ester bearing an alkyl moiety from the supporting-electrolyte cation. However, if the catholyte is partitioned between diethyl ether and aqueous hydrochloric acid before gas chromatographic analysis, phthalide and 2-methylbenzoic acid are observed. Thermally induced reactions that occur in the injector port of the gas chromatograph are responsible for the formation of the 2-methylbenzoate ester as well as for the phthalide found in all electrolyzed solutions.
- Pasciak, Erick M.,Hochstetler, Spencer E.,Mubarak, Mohammad S.,Evans, Dennis H.,Peters, Dennis G.
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p. 557 - 563
(2013/11/19)
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- Electronic and steric effects: How do they work in ionic liquids? the case of benzoic acid dissociation
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(Figure Presented) The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydrogen bond and π-π interactions, namely [bm 2im][NTf2] and [bmpyrr][NTf2]. Data collected show that benzoic acids are less dissociated in ionic liquid than in water solution. Furthermore, the equilibrium constant values seem to be significantly affected by both the nature of ionic liquid cation and the structure of the acid. In particular, the ortho-steric effect seems to operate differently in water and in the aromatic ionic liquid, determining in this solvent medium a particular behavior for ortho-substituted benzoic acids.
- D'Anna, Francesca,Marullo, Salvatore,Vitale, Paola,Noto, Renato
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experimental part
p. 4828 - 4834
(2010/10/04)
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- METAL-CATALYZED SIMULTANEOUS PRODUCTION OF HYDROGEN AND ALKALINE SALTS OF ORGANIC ACIDS
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Metal catalysis of the dehydrogenation of primary alcohols to alkaline salts of the corresponding organic acids is described.Conditions (120-170 deg C) are much milder than those required by the uncatalyzed reactions (220-260 deg C).Hydrogen is evolved in the ratio of two molecules per molecule of alcohol.
- Chiusoli, Gian Paolo,Giroldini, William,Salerno, Giuseppe
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p. 371 - 374
(2007/10/02)
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