- LiHMDS: Facile, highly efficient and metal-free transesterification under solvent-free condition
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Transesterification is one of the important organic reactions employed in numerous industrial as well as laboratory applications for the synthesis of various esters. Herein, we report a rapid, highly efficient, and transition metal-free transesterification reaction in the presence of LiHMDS under solvent-free conditions. The transesterification reaction was carried out with three different benzoate esters and a wide range of primary and secondary alcohols (from C3-C18) in good to excellent yields (45 examples). By considering the commercial role of esters, this method will be promising for the facile synthesis of esters in industry-relevant applications.
- Gore, Kiran R.,Mittapelli, Lavanya L.
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- Esterification of Tertiary Amides by Alcohols Through C?N Bond Cleavage over CeO2
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CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C?N bond cleavage reaction.
- Toyao, Takashi,Nurnobi Rashed, Md.,Morita, Yoshitsugu,Kamachi, Takashi,Hakim Siddiki,Ali, Md. A.,Touchy,Kon, Kenichi,Maeno, Zen,Yoshizawa, Kazunari,Shimizu, Ken-ichi
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p. 449 - 456
(2018/09/11)
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- INTEGRATED PROCESS FOR THE PRODUCTION OF BENZOATE PLASTICIZERS
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The invention relates to a process that integrates the oxidation of toluene to benzoic acid with the production of benzoate plasticizers. Toluene is fed to an oxidation vessel in the presence of oxygen and an oxidation catalyst wherein benzoic acid serves as the solvent for the oxidation. The crude benzoic acid produced is not purified and is then reacted with an alcohol in the presence of an esterification catalyst to produce the crude benzoate ester. The oxidation catalyst, esterification catalyst, and other impurities can be mostly removed from the crude benzoate ester in subsequent washing and filtering steps. The benzoate esters produced through this method can be made in fewer steps with both yields and purities above 80%.
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- Transesterification catalyzed by iron(III) β-diketonate species
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A practical and clean protocol for transesterification catalyzed by a 5 mol % cheap, non-toxic and moisture stable Fe(acac)3 or other iron(III) β-diketonate species in solvent, such as heptane under azeotropic condition is developed. A remarkable rate enhancement was observed upon the addition of 5 mol % of an inorganic base, such as Na2CO3, which suggests that faster formation of a dimeric μ-alkoxy-bridged iron(III) species under alkaline conditions facilitates catalytic turnover. This system provides smooth transesterification over a wide range of structurally diverse esters and alcohols without disturbing functional groups. In addition, the use of iron β-diketonate complexes as catalysts is more environmentally friendly, safer, and economical than other transition-metal catalysts. Preliminary mechanistic studies indicate that the active catalyst is likely a dimeric μ-alkoxy-bridged iron(III) species, as determined by X-ray crystallography of [Fe(dbm)2(O-n-Bu)]2 derived from the alcoholysis of Fe(dbm)3 under alkaline conditions.
- Weng, Shiue-Shien,Ke, Chih-Shueh,Chen, Fong-Kuang,Lyu, You-Fu,Lin, Guan-Ying
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experimental part
p. 1640 - 1648
(2011/04/17)
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- Potassium phosphate / benzyltriethylammonium chloride as efficient catalytic system for transesterification
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Potassium phosphate (K3PO4) in the presence of benzyltriethylammonium chloride have been found to catalyses the transesterifications of a wide variety of aliphatic and aromatic esters with primary and secondary alcohols affording the corresponding esters in good-to-excellent yields.
- Cepanec, Ivica,Zivkovic, Andreja,Bartolincic, Anamarija,Mikuldas, Hrvoje,Litvic, Mladen,Merkas, Sonja
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experimental part
p. 519 - 523
(2010/01/07)
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- Nucleophilic acyl substitutions of esters with protic nucleophiles mediated by amphoteric, oxotitanium, and vanadyl species
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(Chemical Equation Presented) A diverse array of oxometallic species were examined as catalysts in nucleophilic acyl substitution (NAS) reactions of methyl (or ethyl) esters with protic nucleophiles. Among them, oxotitanium acetylacetonate (TiO(acac)2) and vanadyl chloride (VOCl 2-(THF)x) served as the most efficient and water-tolerant catalysts. Transesterifications of methyl and/or ethyl esters with functionalized (including acid- or base-sensitive) 1° and 2° alcohols can be carried out chemoselectively in refluxed toluene or xylene in a 1:1 substrate stoichiometry using 1 mol % catalyst loading. The resultant products were furnished in 85-100% yields by simple aqueous workup to remove water-soluble catalysts. The new NAS protocol is also amenable to amines and thiols in 74-91% yields, albeit with higher loading (2.5 equiv) of protic nucleophiles. Representative examples of commercial interests such as Padimate O and antioxidant additives for plastics were also examined to demonstrate their practical applications. A 1:1 adduct between TiO(acac)2 and a given 1-octadecanol was identified as (C18H37O) 2Ti(acac)2 and was responsible for its subsequent NAS of methyl esters.
- Chen, Chien-Tien,Kuo, Jen-Huang,Ku, Cheng-Hsiu,Weng, Shiue-Shien,Liu, Cheng-Yuan
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p. 1328 - 1339
(2007/10/03)
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- Alcoholysis of Aromatic Carboxylic Esters
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The alcoholysis of various esters of aromatic carboxylic esters with octadecanol in the presence of lead stearate was investigated by chromatographic analysis of the reaction mixtures.The reactivity of the esters was found to be strongly affected by the substitution pattern of the aromatic nucleus as well as by the structure of the alkoxy group.Electron donating substituents in a suitable position lead to a remarkable increase in reactivity compared to the unsubstituted alkyl esters. - Keywords: Mono and polycarboxylic esters; Metal salt catalysis; Kinetics; Chromatographic analysis
- Goedl, Sylvia,Trathnigg, Bernd,Junek, Hans
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p. 1185 - 1198
(2007/10/02)
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- Conversion of Thiocarbonyl Compounds into their Corresponding Oxo-derivatives using Benzeneseleninic Anhydride
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A series of thiocarbonyl compounds including xanthates, thioesters, thioureas, thiocarbonates, and thiones have been converted into their oxo-analogues by treatment with benzeneseleninic anhydride in tetrahydrofuran at room temperature.Except for readily enolised thiones where further oxidation can take place, the method works well and compares favourably with other literature procedures.One example of a selenocarbonyl ester was likewise converted efficiently into the corresponding ester.
- Cussans, Nigel J.,Ley, Steven V.,Barton, Derek H. R.
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p. 1650 - 1653
(2007/10/02)
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