Computational study of the general base catalysed aminolysis of 2-benzoxazolinone

Ilieva, Sylvia; Atanasov, Yasen; Kalcheva, V.; Galabov, Boris

doi:10.1016/s0166-1280(03)00310-5

Cited by 10 publications

(12 citation statements)

References 28 publications

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“…The small energy differences between the concerted and the stepwise process support the experimentally established shifts upon substitution between the two mechanistic pathways in certain ester systems 2 Energies (kcal/mol) Relative to Reactants for the Critical Structures along the Concerted and Stepwise Pathways for the Aminolysis of Methyl Formate a (MF) and Methyl Benzoate (MB) from B3LYP/6-31G(d) Computations uncatalyzedcatalyzedstructureMF E MB E MF E corr b MB E corr b MF E MB E MF E corr b MB E corr b CTS 40.31 43.63 40.12 43.22 26.03 32.88 28.48 34.38 TS1 42.35 46.56 42.33 46.41 17.94 23.08 20.54 25.30 I 6.64 12.77 10.48 15.90 −3.68 0.95 2.34 6.22 TS2 38.53 43.14 38.05 42.11 17.69 23.34 21.13 26.52 P 4.83 7.04 4.64 7.63 4.83 7.04 4.64 7.63 a From ref a. b Corrected for ZPVE contributions. …”

Section: Resultsmentioning

confidence: 67%

“…In the latter, the phenyl ring is directly bonded to the carbonyl functionality and thus able to influence significantly the process. In the present study we compare the estimated activation barriers for the aminolysis of methyl benzoate with the analogous theoretical results for the reaction of methyl formate with ammonia 29a. The theoretical predictions for the uncatalyzed process in the gas phase for the reactions of methyl formate and methyl benzoate with ammonia are compared in the first four columns of Table .…”

Section: Resultsmentioning

confidence: 99%

“…The basic ester aminolysis reaction has been the subject of numerous experimental kinetic − and theoretical studies. − The understanding of the mechanism of the reaction under different conditions is crucial in the search and design of novel catalysts for the process.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of the Aminolysis of Methyl Benzoate: A Computational Study

et al. 2005

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Density functional and ab initio methods were applied in examining the possible mechanistic pathways for the reaction of methyl benzoate with ammonia. Transition state structures and energies were determined for concerted and neutral stepwise mechanisms. The theoretical results show that the two possible pathways have similar activation energies. The general base catalysis of the process was also examined. The predictions reveal that the catalytic process results in considerable energy savings and the most favorable pathway of the reaction is through a general-base-catalyzed neutral stepwise mechanism. The structure and transition vectors of the transition states indicate that the catalytic role of ammonia is realized by facilitating the proton-transfer processes. Comparison of the energetics of the aminolysis for methyl benzoate and methyl formate shows the more favorable process to be that for the aliphatic ester. The differing reactivity of the two esters is explained in terms of the electrostatic potential values at the atoms of the ester functionality.

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Section: Resultsmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

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Mechanism of the Aminolysis of Methyl Benzoate: A Computational Study

et al. 2005

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“…In some more rare cases, the reaction is carried out under acid-catalyzed conditions, especially when one of the partners, either the aldehyde or the acetophenone, is base sensitive (Rendy et al, 2004). BOA, and to a lesser extent BZT, are considered base sensitive (Ilieva et al, 2003). As a consequence, the acid-catalyzed approach appears a priori more favorable.…”

Section: Chemistrymentioning

confidence: 99%

Synthesis and pharmacological evaluation of antioxidant chalcone derivatives of 2(3H)-benzoxazolones

et al. 2008

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Chalcones featuring an analgesic/anti-inflammatory pharmacophore, i.e., the 2(3H)-benzoxazolone heterocycle, on the one hand, and a radical scavenger moiety, i.e., 2,6-di-t-butylphenol, on the other hand were synthesized by condensation of a ketone 2(3H)-benzoxazolone precursor with 3,5-di-t-butyl-4-hydroxybenzaldehyde. Among the various methods explored (acid homogenous or heterogenous catalysis, base catalysis), heterogenous catalysis conditions using KSF Montmorillonite were found to be the most convenient. The E-geometry of the soobtained chalcones was ascertained both by 1 H and 13 C-nuclear magnetic resonance (NMR) spectroscopy as well as B3LYP/6-31G ** quantum mechanics calculations. Chalcones 1-8 were pharmacologically evaluated in vitro for their ability to prevent human low-density lipoprotein (LDL) copper-induced oxidation using Cu 2? as oxidizing agent. Compound 4 emerged as the most promising agent as it was able to inhibit copper-mediated human LDL oxidation with an activity ten times greater than that of Probucol, a reference antioxidant drug.

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“…It should be noted that Flory [9,10] and Tang [11] and co-workers, who studied the kinetics of catalytical esterification in the absence and presence of the catalyst, established that in the absence of a catalyst, the reaction obeys the 3 rd and 2 0.5th order, and in the presence of a catalyst ̶ laws 2 nd order (bimolecular mechanism). The mechanism and kinetics of catalytical esterification have been investigated in the past as well as today [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Influence of Different Catalysts and Solvents on the General Base Catalytical Esterification of Polyoxyethylene Sorbitan Trioleate with Maleic Anhydride and Styrene-Co-Maleic Anhydride

et al. 2013

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The general base catalitycal esterification of Polyoxyethylene sorbitane Trioleate with maleic anhydride (Ma) and styrene-co-maleic anhydride (Sma) using pyridine as catalyst is described. We investigated the effect of different factors on the yield of reaction product. The analysis of the effect of different factors on the process of catalytical esterification showed that the catalysts and solvents can be arranged by their activity in the following order: sulfuric acid > toluene sulfonic acid > triethylamine > pyridine > without a catalyst and dimethylsulfoxide (DMSO) > O-xylene > dimethylformamide (DMF), respectively. It should be noted that pyridine to its activity is not significantly inferior to the traditional catalysts and with DMSO using the yield of product is increasing. It is concluded that the reaction proceeds by 2nd order. It was found that decreasing the temperature of reaction to a lower temperature, where there is an intensive incubation period, leads to decreasing of yield of polyesters. The rate constant and activation energy were calculated. It was found that the process occurred on 98% at 130 °С and 80 min for PoesTo/Ma and on 88% at 150 °С and 40 min for PoesTo/Sma. For preparation of reaction product to analysis new methods were developed. It was shown, that on 1H and 13C spectra an overlap of the individual peaks or their close concentration in one area is observed, which makes it not possible to complete the analysis of the spectra. 1H and 13C spectra give a preliminary idea of the structure of the reaction products. It is concluded that 2-D NMR measurements more useful for further confirming of structure of PoesTo/Ma and PoesTo/Sma. HLB shown that we obtained two different surfactants where by catalytical esterification the hydrophilic part of Tween in PoesTo/Ma and the lipophilic part in PoesTo/Sma was increased.

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Computational study of the general base catalysed aminolysis of 2-benzoxazolinone

Cited by 10 publications

References 28 publications

Mechanism of the Aminolysis of Methyl Benzoate: A Computational Study

Mechanism of the Aminolysis of Methyl Benzoate: A Computational Study

Synthesis and pharmacological evaluation of antioxidant chalcone derivatives of 2(3H)-benzoxazolones

Influence of Different Catalysts and Solvents on the General Base Catalytical Esterification of Polyoxyethylene Sorbitan Trioleate with Maleic Anhydride and Styrene-Co-Maleic Anhydride

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