- Zirconium based ion exchangers as catalysts in esterification reactions of benzoic acid
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Zirconium based double salts were used as catalysts in esterification reactions of benzoic acid with some primary and secondary alcohols. Ester products were characterized with 1H NMR and FT-IR techniques. Product yields from different set of combinations of benzoic acid and alcohols were monitored using gas chromatography. Double salt based ion exchangers selectively catalyzed esterification reactions based on steric considerations. Electronic factor did not seem to play any role in efficiency of the inorganic ion exchangers as heterogeneous catalysts.
- Singh, Charanjit,Mittal, Susheel K.,Kaur, Navneet
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Read Online
- Unusual Reaction of 6-Nitrobenzotriazolyl Carboxylates with Grignard Reagents
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The reaction of 6-nitrobenzotriazolyl carboxylates with Grignard reagents afforded various carboxylates in fairly good yields.
- Okawara, Tadashi,Ikeda, Norihiro,Yamasaki, Tetsuo,Furukawa, Mitsuru
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Read Online
- N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
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N-Aroylbenzotriazoles have been shown to be efficient reagents for esterification in the absence of organic solvent. Grinding of N-aroylbenzoytiazoles with twofold excess of alcohols for a couple of hours at room temperature gave corresponding esters in high percentage of yields.
- Hahnvajanawong, Viwat,Phungpis, Baramee
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p. 2671 - 2674
(2021/10/25)
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- Metal nitrate-catalyzed one-pot oxidative esterification of benzaldehyde with hydrogen peroxide in alcoholic solutions at room temperature
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The activity of metal nitrate catalysts was investigated in the oxidative esterification reactions of benzaldehyde with hydrogen peroxide. Several types of metal nitrates (alkaline, alkaline earth, and transition metals) were evaluated as catalysts. Among the assessed salts, Fe(NO3)3 was the most efficient catalyst toward the formation of the target product (i.e., benzoic alkyl ester). In methyl alcohol, benzaldehyde was selectively oxidized to benzoic acid and then esterified to methyl benzoate. The efficiency of the catalyst was correlated with its higher Lewis acidity character, which was established through the pH measurements of methanolic solutions of the soluble metal nitrate salts. The influence of main variables of the reaction, such as catalyst load, temperature, and reactant stoichiometry, was investigated. The size of the carbon chain and steric hindrance played an essential role in the reaction selectivity. While methyl and ethyl alcohols selectively provided ester as the main product (ca. 70-75%) and acetal as the subproduct, the other alcohols gave ester, hemiacetal, and benzoic acid, which was formed in the least amount. The use of an inexpensive catalyst, a green oxidant, mild conditions, and short reaction times were the positive aspects of this one-pot process. The high TON (ca. 900) is evidence of the high catalytic activity of Fe(NO3)3. It is noteworthy that this methodology does not rely upon ligands and other additives.
- Da Silva, Márcio José,De Oliveira, Cesar Macedo
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p. 3683 - 3691
(2021/03/03)
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- Electrochemical esterification via oxidative coupling of aldehydes and alcohols
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An electrolytic method for the direct oxidative coupling of aldehydes with alcohols to produce esters is described. Our method involves anodic oxidation in presence of TBAF as supporting electrolyte in an undivided electrochemical cell equipped with graphite electrodes. This method successfully couples a wide range of alcohols to benzaldehydes with yields ranging from 70 to 90%. The protocol is easy to perform at a constant voltage conditions and offers a sustainable alternative over conventional methods.
- Smeyne, Dylan,Verboom, Katherine,Bryan, Maria,LoBue, James,Shaikh, Abid
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supporting information
(2021/03/26)
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- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
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The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
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supporting information
p. 2652 - 2657
(2021/04/21)
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
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The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
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supporting information
p. 4550 - 4554
(2019/08/21)
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- Synthesis, characterization and catalytic performances of benzimidazolin-2-iminato actinide (IV) complexes in the Tishchenko reactions for symmetrical and unsymmetrical esters
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A new family of benzimdazolin-2-iminato actinide?(IV) complexes [(Bim7-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (3), Th (4)) and [(Bim4-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (5), Th (6)) were synthesized and their solid state structures were established by single-crystal X-ray diffraction analysis. The catalytic performances of complexes 3–6 towards the homo- and cross-coupling of aldehydes (Tishchenko reaction) were studied and the thorium complexes 4 and 6 displayed moderate to high activities for the production of the corresponding symmetric and unsymmetrical esters. Coupling of aldehyde and alcohols, known as the tandem proton-transfer esterification, and the intermolecular coupling reaction between aldehyde and trifluoromethylketones were also investigated by these thorium complexes, indicating a complementary method to obtain unsymmetrical esters selectively. Plausible mechanisms for these reactions are proposed based on stoichiometric studies.
- Liu, Heng,Khononov, Maxim,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
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p. 123 - 137
(2017/10/25)
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- Zirconocene-catalyzed direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio under solvent-free conditions
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A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C-Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.
- Tang, Zhi,Jiang, Qiutao,Peng, Lifen,Xu, Xinhua,Li, Jie,Qiu, Renhua,Au, Chak-Tong
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supporting information
p. 5396 - 5402
(2017/11/22)
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- DBU-Based Dicationic Ionic Liquids Promoted Esterification Reaction of Carboxylic Acid with Primary Chloroalkane Under Mild Conditions
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Abstract: A series of DBU-based (DBU = 1, 8-diazabicyclo [5.4.0] undec-7-ene) dicationic ionic liquids with different anions were successfully synthesized by the reaction of DBU and 1, 6-dichlorohexane. Therein, the dicationic ionic liquid 1, 1′-(hexane-1, 6-diyl)bis(1, 8-diazabicyclo [5.4.0]undec-7-enium) dichlorine (IL-1) was successfully employed as an efficient catalyst in esterification reaction of carboxylic acids with primary chloroalkanes under mild conditions without any additional basic reagents. Moreover, the optimum catalyst could be efficiently reused for five times without any significant change on the catalytic effect. The improved protocol is not only efficient, but also green and pollution-free.
- Liu, Yang,Mao, Guijie,Zhao, Hongyan,Song, Jinyi,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
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p. 2764 - 2771
(2017/09/14)
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- An electrochemical method for carboxylic ester synthesis from N-alkoxyamides
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An electrochemical method for the synthesis of carboxylic as well as hindered esters from N-alkoxyamides has been reported. The electrochemical reaction proceeds through constant current electrolysis (CCE) by taking advantage of the dual role of n-Bu4NI (TBAI) as the redox catalyst as well as the supporting electrolyte. Besides providing mild reaction conditions, the present protocol is free from external oxidants and conducting salts, thereby generating nitrogen as the nonhazardous side product. Additionally, the developed procedure is highly advantageous due to its short reaction time, wide substrate scope, and gram-scale synthesis.
- Subramanian, Kripa,Yedage, Subhash L.,Bhanage, Bhalchandra M.
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p. 10025 - 10032
(2018/05/31)
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- Thorium complexes possessing expanded ring N-heterocyclic iminato ligands: Synthesis and applications
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Six and seven membered N-heterocyclic iminato ligands (L) are introduced allowing access a new class of Th(iv) complexes of the type Cp?2Th(L)(CH3). These complexes were studied in the Tishchenko reaction. Stoichiometric reactions together with kinetic and thermodynamic studies permit us to propose a plausible mechanism.
- Ghatak, Tapas,Drucker, Shani,Fridman, Natalia,Eisen, Moris S.
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supporting information
p. 12005 - 12009
(2017/09/25)
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- Acid promoted C-C bond oxidative cleavage of β-O-4 and β-1 lignin models to esters over a copper catalyst
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Depolymerisation of lignin to aromatics is a challenging task. We herein report that a Cu(OAc)2/BF3·OEt2 catalyst is effective in simultaneously cleaving C-C bonds in β-1 and β-O-4 ketones, yielding esters and phenols. In-depth studies show that C-H bond activation is the rate determining step for C-C bond cleavage. BF3·OEt2 promotes the reaction via activating the β-C-H bond. This study offers the potential to obtain aromatic esters from lignin.
- Wang,Li,Lu,Li,Zhang,Liu,Luo,Wang
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p. 702 - 706
(2017/08/15)
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- Amberlyst-15 catalysed oxidative esterification of aldehydes using a H2O2 trapped oxidant as a terminal oxidant
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A simple and efficient method has been developed for the selective oxidative esterification of aldehydes using commercially available Amberlyst-15 as a catalyst. H2O2 released from a clathrate structured 4Na2SO4·2H2O2·NaCl oxidant serves as an efficient source of terminal oxidants. Various aromatic, heteroaromatic, and aliphatic aldehydes undergo selective esterification to give good to excellent yield. The heterogeneous catalyst, Amberlyst-15, exhibits high reactivity and can be recycled over several runs. The 4Na2SO4·2H2O2·NaCl oxidant was found to be superior to commonly used oxidizing agents providing an anhydrous, easy to handle and stable form of H2O2
- Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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p. 2695 - 2701
(2017/04/03)
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- Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
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A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.
- Hu, Yongke,Li, Bindong
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p. 7301 - 7307
(2017/11/29)
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- Palladium-catalyzed carbonylation of aryl halides: An efficient, heterogeneous and phosphine-free catalytic system for aminocarbonylation and alkoxycarbonylation employing Mo(CO)6 as a solid carbon monoxide source
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Immobilized palladium metal-containing magnetic nanoparticles (ImmPd(0)-MNPs) were synthesized and characterized as an immobilized, phosphine-free catalyst for carbonylation reactions, namely the alkoxycarbonylation and aminocarbonylation reactions. Various substituted aryl iodides tolerated the reaction conditions and a wide variety of alcohols and amines were used efficiently. The effects of the solvent, base, and temperature were studied in both the mentioned reactions. The developed catalytic system avoids the use of phosphine ligands and can be reused for up to eight consecutive cycles. The recycled catalyst was characterized by TEM and ICP analysis.
- Hajipour, Abdol-Reza,Tavangar-Rizi, Zeinab,Iranpoor, Nasser
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p. 78468 - 78476
(2016/09/09)
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- Green alternative solvents for the copper-catalysed arylation of phenols and amides
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Investigation of the use of green organic solvents for the Cu-catalysed arylation of phenols and amides is reported. Alkyl acetates proved to be efficient solvents in the catalytic processes, and therefore excellent alternatives to the typical non-green solvents used for Cu-catalysed arylation reactions. Solvents such as isosorbide dimethyl ether (DMI) and diethyl carbonate also appear to be viable possibilities for the arylation of phenols. Finally, a novel copper catalysed acyl transfer process is reported.
- Sambiagio, Carlo,Munday, Rachel H.,John Blacker,Marsden, Stephen P.,McGowan, Patrick C.
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p. 70025 - 70032
(2016/08/06)
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- Silver-mediated oxidative aliphatic C-H trifluoromethylthiolation
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The first example of a practical and direct trifluoromethylthiolation reaction of unactivated aliphatic C-H bonds employs a silver-based reagent. The reaction is operationally simple, scalable, and proceeds under aqueous conditions in air. Furthermore, its broad scope and good functional-group compatibility were demonstrated by applying this method to the selective trifluoromethylthiolation of natural products and natural-product derivatives.
- Guo, Shuo,Zhang, Xiaofei,Tang, Pingping
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supporting information
p. 4065 - 4069
(2015/03/30)
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- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
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2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
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p. 287 - 291
(2015/01/30)
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- Mixed Imidazolin-2-iminato-Cp? Thorium(IV) Complexes: Synthesis and Reactivity Toward Oxygen-Containing Substrates
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The mixed pentamethylcyclopentadienyl thorium(IV) imidazolin-2-iminato complexes Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) were synthesized in quantitative yields via rapid protonolysis of Cp?2Th(Me)2 (1) with the respective neutral imidazolin-2-iminato ligand ImRNH. Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) display short Th-N bond lengths and large Th-N-C angles. The reactivity of complex 2 and 3 toward oxygen-containing substrates was studied, and the catalytic activity of 2 was compared to the dimethyl (bispentamethyl-cyclopentadienyl) thorium complex 1. Complex 2 was applied in the catalytic Tishchenko reaction with aromatic, heteroaromatic, and branched aliphatic aldehydes, displaying a higher catalytic activity than Cp?2Th(Me)2 and Cp?2Th(ImMesN)(Me). Furthermore, 2 was applied as a catalyst in the crossed Tishchenko reaction and in the oligomerization of bis(aldehydes), as well as in the ring-opening polymerization of ε-caprolactone. In all reactions, the activity of Cp?2Th(ImDippN)(Me) (2) and Cp?2Th(ImMesN)(Me) (3) was higher than that observed for Cp?2Th(Me)2 (1), which can be attributed to the increased electron density introduced by the coordination of the imidazolin-2-iminato ligand. (Chemical Equation Presented).
- Karmel, Isabell S. R.,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
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supporting information
p. 2933 - 2942
(2015/06/30)
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- One-pot esterification and amide formation via acid-catalyzed dehydration and ritter reactions
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Esterification of carboxylic acid is achieved using acetonitrile as a water trap. Water liberated during esterification is consumed in cyanide hydrolysis, thereby driving the esterification to completion. Substrates having carboxylic acid and nitrile groups undergo intramolecular dehydration and rehydration to amido esters in the absence of acetonitrile. Cyano acids also undergo esterification and Ritter reaction in one pot when excess alcohol is used. For the first time, we have observed an interesting Ritter reaction of primary alcohols, leading to ester amide product in one pot. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Dawar, Pankaj,Raju, M. Bagavan,Ramakrishna, Ramesha Andagar
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supporting information
p. 836 - 846
(2014/03/21)
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- Versatile and sustainable alcoholysis of amides by a reusable CeO 2 catalyst
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CeO2 catalyzed the esterification between an equivalent molar ratio of primary amides and alcohols under neutral conditions, which provides the first versatile reusable catalytic system for direct alcoholysis of amides to esters with wider scope and 67 times higher turnover number (TON) than previous catalytic systems.
- Siddiki, S. M. A. Hakim,Touchy, Abeda Sultana,Tamura, Masazumi,Shimizu, Ken-Ichi
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p. 35803 - 35807
(2014/11/07)
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- A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst-media combined systems
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A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability.
- Wang, Yinglei,Zhi, Huizhen,Luo, Jun
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- Synthesis of new oxidant N-chloroisonipecotamide and its oxidation kinetics on aromatic acetals
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The new oxidant N-chloroisonipecotamide (NCINA) is prepared by standard procedure and characterized. The formal redox potential, physical constant, elemental analysis and spectral characterization (IR, 1H-NMR and Mass spectrum) confirms the presence of nitrogen-halogen bond. It is found to be a mild and stable oxidant and formal redox potential of N-chloroisonipecotamide shows that it can be used as an effective source of positive halogen, like other existing oxidants. Oxidation of benzaldehyde di-n-alkyl acetals is carried out with new oxidant in acetonitrile medium. The reaction is first order with respect to NCINA and zero order with respect to acetals. The effect of isonipecotamide and acetonitrile is studied. Increase in ionic strength has marginal effect on the rate. A mechanism consistent with the observed kinetic results has been elucidated.
- Shenbagam,Mathiyalagan
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p. 747 - 752
(2013/11/06)
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- Kinetics and mechanism of oxidation of aromatic acetals by N-chloronicotinamide in acetonitrile medium
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An effort has been made to Introduce N-chloronicotinamide (NCN) as an oxidant to some aromatic acetals. The reaction shows total first order kinetics, zero order in [acetal] and first order in [NCN]. Increase in ionic strength has marginal effect on the rate while increase in dielectric constant of the medium decreases the rate. Further the rate is slightly decreased by the addition of nicotinamide. Arrhenius parameters and activation parameters are calculated. A mechanism consistent with the observation is proposed and an appropriate rate law is derived.
- Shenbagam,Mathiyalagan
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p. 1343 - 1346
(2013/02/22)
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- Dual Bronsted acid/nucleophilic activation of carbonylimidazole derivatives
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Carbonylimidazole derivatives have been found to be highly active acylation reagents for esterification and amidation in the presence of pyridinium salts. These reactions are thought to involve both Bronsted acid and nucleophilic catalysis. This mode of activation has been applied to the synthesis of difficult to access oxazolidinones, as well as esters and amides. Finally, the use of pyridinium salts has been shown to accelerate the esterification of carboxylic acids with imidazole carbamates.
- Heller, Stephen T.,Fu, Tingting,Sarpong, Richmond
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supporting information; experimental part
p. 1970 - 1973
(2012/06/01)
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- Novel Bronsted-acidic ionic liquids based on benzothiazolium cations as catalysts for esterification reactions
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Three novel Bronsted-acidic ionic liquids based on benzothiazolium cations were prepared, which served as catalysts for the synthesis of benzoic esters. All three gave good yields of the target esters in esterification reactions. Moreover, they combine the advantages of both homogeneous and heterogeneous solid catalysts in esterification reactions, which enabled them to serve as homogeneous catalysts to catalyze the reactions and be conveniently recovered by simple filtration after the reactions. They could be reused several times without noticeable decrease in efficiency. Copyright 2011 (CC) SCS.
- Zhou, Xian Si,Liu, Jia Bing,Luo, Wen Feng,Zhang, Yi Wen,Song, Hang
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experimental part
p. 1607 - 1615
(2012/05/04)
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- Palladium-catalyzed aerobic oxidative direct esterification of alcohols
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One step from alcohol to ester: A palladium-catalyzed oxidative esterification of various benzylic alcohols with methanol and long-chain aliphatic alcohols was carried out in the presence of molecular oxygen as the oxidant (see scheme). By considering the effects of substitution and potential mechanistic pathways, the applicability of this method to a range of different substrates was shown. Copyright
- Liu, Chao,Wang, Jing,Meng, Lingkui,Deng, Yi,Li, Yao,Lei, Aiwen
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supporting information; experimental part
p. 5144 - 5148
(2011/06/26)
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- An efficient and green approach for the esterification of aromatic acids with various alcohols over H3PO4/TiO2-ZrO 2
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TiO2-ZrO2 was prepared with surfactant through a sol-gel method. Catalysts containing 5 - 35% H3PO4 were prepared using these oxides. Subsequently the catalytic performance of prepared catalysts was determined for liquid phase esterification of aromatic acids. H3PO4/TiO2-ZrO2 has been used as catalyst to synthesize various novel esters by esterification of some aromatic acids with aliphatic alcohols (2-propanol, 1-butanol, iso butanol, 3-pentanol, 1-hexanol, heptanol, cyclo heptanol, octanol and decanol). Under optimized conditions, maximum yields and selectivity (100%) to the corresponding ester, was obtained by using 25 wt % H3PO4/TiO 2-ZrO2 as catalyst. The Catalyst can be easily recycled after reaction and can be reused without any significant loss of activity/selectivity performance. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present synthetic protocol. The reaction was carried out under solvent-free condition.
- Kalbasi, Roozbeh Javad,Massah, Ahmad Reza,Barkhordari, Zeynab
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experimental part
p. 2361 - 2367
(2010/11/18)
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- A simple and efficient recyclable phosphine-free catalytic system for alkoxycarbonylation and carbonylative Sonogashira coupling reactions of aryl iodides
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Using palladium on charcoal (Pd/C) and triethylamine as a novel, efficient, versatile, recyclable, and phosphine-free catalytic system, we carried out the alkoxycarbonylation of aryl iodides (alcohols or phenols as nucleophiles) and the carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes, affording the corresponding aryl esters and α, β-alkynyl ketones in good to excellent yields under mild conditions. We found that both electron-withdrawing and electron-donating substituents on phenol enhanced the phenoxycarbonylation of iodobenzene. The recyclability of Pd/C was also demonstrated.
- Liu, Jianhua,Chen, Jing,Xia, Chungu
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- Radical-chain redox rearrangement of cyclic benzylidene acetals to benzoate esters in the presence of thiols
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Cyclic benzylidene acetals derived from 1,2- and 1,3-diols undergo an efficient ring-opening redox rearrangement to give benzoate esters in the presence of a peroxide initiator and a thiol, which acts as a polarity-reversal catalyst to promote the radical-chain reaction.
- Roberts, Brian P.,Smits, Teika M.
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p. 137 - 140
(2007/10/03)
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- Linear free energy relationship and conformational effects on oxidation of aromatic acetals by pyridinium fluorochromate
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Kinetics of oxidation of aromatic acetals by pyridiniumfluorochromate (PFC) in aqueous acetic acid medium reveal that the reactions are second order, first order each in [acetal] and [PFC]. The presence of electron- withdrawing substituents in the benzene ring enhances the rate of oxidation while that of opposite one retards it. The small ρ value suggests a mechanism with little charge separation. The rate of oxidation depends on the nature of alkyl group and conformational effects.
- Ramakrishnan,Nambi
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p. 232 - 234
(2007/10/03)
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- 2-Acyloxy-4,6-dimethoxy-1,3,5-triazine - A new reagent for ester synthesis
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2-Acyloxy-4,6-dimethoxy-1,3,5-triazines obtained in reaction between carboxylic acid and 2-chloro-4,6-dimethoxy-1,3,5-triazine were used as acylating agents for the synthesis of esters from primary, secondary, and tertiary alcohols. Because of mild acylation conditions the method could be applied to esterification of labile alcohols with aromatic and aliphatic (also α-branched) acids in good yields.
- Kaminska, Janina E.,Kaminski, Zbigniew J.,Gora, Jozef
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p. 593 - 596
(2007/10/03)
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- Effect of solvents on the rearrangement of aromatic acetals by iodobenzene dichloride
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Hypervalent iodine compounds have been reported to be used in organic synthesis, conversion of organolithium compounds to hydrocarbons, preparation of coordination compounds and in chlorination reactions. The present paper is a report on the reaction of iodobenzene dichloride on benzaldehyde di-n-butyl acetal and benzaldehyde di-isobutyl acetal in different solvents.
- Selvaraj, S. Joseph,Antony, T. V.
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p. 943 - 944
(2007/10/03)
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- Cobalt(II)chloride catalysed cleavage of ethers with acyl halides: Scope and mechanism
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Cobalt(II) chloride in acetonitrile catalyses the cleavage of a wide variety of ethers with acyl halides under mild conditions to give the corresponding esters in good yields. Acyclic aliphatic ethers are cleaved to the corresponding ester and chlorides whereas the cyclic aliphatic ethers give rise to the ω-chloroesters. The benzyl ethers can be converted to the corresponding esters along with the formation of benzyl chloride and benzyl acetamide. A comparative study for the cleavage of allyl and benzyl ether has revealed that benzyl ether can be selectively cleaved in presence of the allyl ethers. The oxiranes can be cleaved in highly regioselective manner to the corresponding-β-chloroesters. The vinyl ethers undergo sp2-hybridised carbon-oxygen bond cleavage under these conditions. Based on product analysis, a mechanism involving electron transfer followed by O-acylation and S(N)1 or S(N)2 attack by chloride-ion is discussed.
- Iqbal,Srivastava
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p. 3155 - 3170
(2007/10/02)
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- A novel and convenient method for palladium-catalysed alkoxycarbonylation of aryl and vinyl halides using HCO2R/NaOR system
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Aryl iodides, vinyl bromides and tricarbonyl(chloroarene)chromium complexes react under mild conditions with sodium alkoxides and alkyl formates as source of carbon monoxide in the presence of dichlorobis(triphenylphosphine)-palladium as catalyst to give the corresponding carboxylic esters in high yields.
- Carpentier,Castanet,Brocard,Mortreux,Petit
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p. 4705 - 4708
(2007/10/02)
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- Cobalt(II) Chloride Catalysed Acylative Cleavage of Ethers
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In the presence of catalytic amount of cobalt(II) chloride in acetonitrile, a wide variety of ethers are cleaved with acyl chlorides, to the corresponding esters in good to excellent yield.
- Ahmad, Saeed,Iqbal, Javed
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p. 953 - 956
(2007/10/02)
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- The Reaction of N-Carboalkoxy Reissert Analogs with Carboxylic Acids
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The reaction of N-carboalkoxy Reissert analogs in the presence of carboxylic acids yields the corresponding ester and heterocyclic base.Use of methoxy substituted benzoic acids yields, instead of the ester, the respective anhydride.Amides can also be prepared in a similar fashion.
- Popp, Frank D.,Duarte, Frederick F.,Uff, Barrie C.
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p. 1353 - 1355
(2007/10/02)
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- Rearrangement of Aromatic Acetals Over Solid Acid Catalysts
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The reactions of aromatic acetals (1a-6a) catalysed by aluminium phosphate (AP) yield the corresponding esters (b), ethers (c) and the parent aldehydes (d).Similar reactions over aluminium sulphate (AS) give only esters (b) and the aldehydes (d).Probable mechanisms have been suggested for the reactions.The catalysts have been characterized by various studies.The specific poisoning of the catalysts have been done with NH3 and CO2 and the product formation on the poisoned catalyst provides support to the suggested mechanisms.
- Xavier, N.,Arulraj, S. J.
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p. 519 - 522
(2007/10/02)
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- Nitrosation of the N-Alkyl-O-acylhydroxylamines. A New Deamination Method.
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The nitrosation of N-alkyl-O-acylhydroxylamines leads to immediate decomposition at dry ice temperatures; the corresponding ester and nitrous oxide are formed.An 18O study has shown that the nitroso-O-acylhydroxylamines fragment directly rather than undergo a rearrangement reaction (as observed with the nitrosoamides).The product yields are respectable, especially at low tempreatures, and the method has promise for the generation of high energy carbonium ions.
- White, Emil H.,Ribi, Max,Cho, Lee K.,Egger, Notker,Dzadzic, Petar M.,Todd, Michael J.
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p. 4866 - 4871
(2007/10/02)
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- Synthesis and Decomposition of the N-Alkyl-N-nitro-O-benzoylhydroxylamines
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Nitration of N-alkyl-O-benzoylhydroxylamines yields the correspondng N-nitro derivatives.At modest temperatures these compounds decompose to yield alkyl benzoates, alkenes, benzoic acid, and nitrous oxide.In the case of primary alkylnitrohydroxylamines, nitroalkanes and alkyl nitrates are also formed.The alkyl benzoates are products of ionic reactions since skeletal rearrangements characteristics of carbonium ions occur.The insensivity of the rates of decomposition to solvent polarity suggests that the rate-determining step is a rearrangement rather than direct ionization.
- White, Emil H.,Reefer, John,Erickson, Ronald H.,Dzadzic, Petar M.
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p. 4872 - 4876
(2007/10/02)
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- PHOTOINDUCED ALCOHOLYSIS OF alpha , alpha , alpha -TRIBROMACETOPHENONE TO BENZOYLFORMATE.
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Irradiation of p-substituted alpha , alpha , alpha -tribromoacetophenones (1) in O//2-saturated alcohols (MeOH, prim. and sec. alcohols) afforded a new alcoholysis product, benzoylformate (2), in good yield (75-85%) along with benzoate and radical (reduction) products. Sensitization experiments showed that 2 was derived from the triplet excited 1. Formation of 2 as well as the decomposition rate of 1 were greatly accelerated by oxygen, presumably as a result of the involvement of the normally forbidden S//o yields T//1 transition of 1 due to the oxygen-1 charge transfer complex. Independent synthesis and reaction of possible intermediates in the photoalcoholysis of 1 leading to 2 suggested that 2 was formed from spontaneous (dark) reactions of initial photoalcoholysis product, alpha alpha -dibromo- alpha -alkoxyacetophenone.
- Izawa,Ishiguro,Tomioka
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p. 1490 - 1496
(2007/10/02)
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- Effect of Metal Ions in Organic Synthesis. XI - Hydrolysis and Alcoholysis of Some Acylhydrazines and N-Acyl-N'-arenesulphonylhydrazines in the Presence of Copper(II) Chloride
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Die Hydrolyse und Alkoholyse einiger Acylhydrazine und N-Acyl-N'-arensulfonylhydrazine in Gegenwart von Kupfer(II)-chlorid * 2 H2O wurden untersucht.Das Mesitylensulfonylhydrazid und die 2,4,6-Triisopropylbenzensulfonylhydrazid-Derivate sind reaktiver als die entsprechenden Hydrazine oder Tosylhydrazid-Derivate.Die entsprechenden Carbonsaeuren und Ester erhaelt man in guten Ausbeuten und unter sehr milden Bedingungen.Die vorliegende Methode ist einfach und bequem im Vergleich zu anderen Methoden.Die Reaktion verlaeuft wahrscheinlich ueber Kupferkomplexe der Acylhydrazine.
- Attanasi, Orazio,Serra-Zanetti, Franco
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p. 901 - 907
(2007/10/02)
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- A CONVENIENT METHOD FOR THE PREPARATION OF CARBOXYLIC ESTERS
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8-Quinolinesulfonyl tetrazolide (QS-t) was found to be a useful coupling agent for the preparation of carboxylic esters.KEYWORDS--esterification; carboxylic esters; coupling agent; coupling reaction; base; alcohols; carboxylic acids
- Takaku, Hiroshi,Sasaki, Naohiko,Morita, Kazuhiro
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p. 2633 - 2634
(2007/10/02)
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- POLARISATION NUCLEAIRE INDUITE CHIMIQUEMENT: ETUDE COMPARATIVE DE LA DECOMPOSITION THERMIQUE ET PHOTOCHIMIQUE DE PEROXYDES D'ACYLE BENZOYLE
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A comparative CIDNP study of the thermal and photochemical decomposition of acyl benzoyl peroxides PhCO2O2CR (R=methyl and isobutyl) has provided an explanation of the effect of the mode of initiation on the course of the decomposition of this class of peroxides and on the product distribution.The observed variations result from an important decrease (from 1E-8 sec to less than 1E-10 sec) in the lifetime of the benzoyloxy radical on changing from thermal to photochemical initiation.
- Nedelec, J. Y.,Lefort, D.
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p. 3199 - 3204
(2007/10/02)
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- Novel esterifying agents, and their production and use
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A process for esterifying organic carboxylic acids which comprises reacting an organic carboxylic acid with a carbonic acid ester of the formula: EQU1 wherein R is an organic group and X and Y are each a negative group in the presence of a basic substance to make esterified the carboxyl group in the organic carboxylic acid. The process is advantageous in affording the objective carboxylic ester in a good yield within a short time by a simple operation under a mild reaction condition.
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