Quantum-chemical study on thermal transformations of urea in ethylene glycol

Samuilov, A. Ya.; Valeev, A. R.; Balabanova, F. B.; Samuilov, Ya. D.; Коновалов, А. И.

doi:10.1134/s1070428013010065

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…The similar effect has been demonstrated in the case of urea decomposition into isocyanic acid and ammonia in ethylene glycol [22]. Moreover, the reactivity of alcohol associates as substrates is enhanced as compared to the monomeric alcohol molecules.…”

Section: Catalysis Of Carbamate-azomethinenol Tautomeric Transformatisupporting

confidence: 74%

Alcohol associates as catalysts of tautomeric transformations

et al. 2015

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The B3LYP/6-311++G(df,p) quantum-chemical simulation has revealed that linear associates of methanol catalyze the ketone-enol, nitro-aci-nitro, and carbamate-azomethinenol tautomeric transformations. All the reactions proceed via the coherent transition states. The catalytic effect is enhanced with the increased alcohol degree of association. The acid-base properties of methanol are changed similarly.

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Section: Catalysis Of Carbamate-azomethinenol Tautomeric Transformatisupporting

confidence: 74%

Alcohol associates as catalysts of tautomeric transformations

et al. 2015

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“…We previously showed that ethylene glycol associates catalyze the decomposition of urea and the reaction of isocyanic acid with ethylene glycol [1,18]. Therefore, there exists the possibility for catalysis by ethylene glycol molecules of all three steps of the transformation of urea into ethylene carbonate.…”

Section: Rupture Of the O-h And C-n Bonds And Formation Of The N-h Anmentioning

confidence: 99%

“…We previously studied the decomposition of urea in ethylene glycol into ammonia and isocyanic acid [18] and the reaction of isocyanic acid with ethylene glycol associates [1]. The third step in this process, the trans-formation of 2-hydroxyethyl carbamate into ethylene carbonate is slow.…”

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confidence: 99%

Thermal transformations of urea in ethylene glycol: III. Transformation of 2-hydroxyethyl carbamate into ethylene carbonate

et al. 2015

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“…The authors calculated and compared energy profiles of the different reaction paths and concluded that auto‐catalytic mechanisms are favored. In a series of studies, Samuilov et al [37,44−51] . investigated reactions of different isocyanates and alcohols based on B3LYP.…”

Section: Introductionmentioning

confidence: 99%

“…indicate that urethane groups may act as auto‐catalyst in a reaction via transition states with 8‐rings [50] . Moreover, the authors used the PCM solvation model to account for the influence of the reaction medium and found that the activation barriers are influenced by solvent polarity [51] . Besides Samuilov et al., also other researchers have compared reaction mechanisms with addition of the hydroxy group of the alcohol to the C=N and C=O bonds in isocyanates.…”

Section: Introductionmentioning

confidence: 99%

Reaction Mechanisms and Rate Constants of Auto‐Catalytic Urethane Formation and Cleavage Reactions

et al. 2021

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The chemistry of urethanes plays a key role in important industrial processes. Although catalysts are often used, the study of the reactions without added catalysts provides the basis for a deeper understanding. For the non‐catalytic urethane formation and cleavage reactions, the dominating reaction mechanism has long been debated. To our knowledge, the reaction kinetics have not been predicted quantitatively so far. Therefore, we report a new computational study of urethane formation and cleavage reactions. To analyze various potential reaction mechanisms and to predict the reaction rate constants quantum chemistry and transition state theory were employed. For validation, experimental data from literature and from own experiments were used. Quantitative agreement of experiments and predictions could be demonstrated. The calculations confirm earlier assumptions that urethane formation reactions proceed via mechanisms where alcohol molecules act as auto‐catalysts. Our results show that it is essential to consider several transition states corresponding to different reaction orders to enable agreement with experimental observations. Urethane cleavage seems to be catalyzed by an isourethane, leading to an observed 2nd‐order dependence of the reaction rate on the urethane concentration. The results of our study support a deeper understanding of the reactions as well as a better description of reaction kinetics and will therefore help in catalyst development and process optimization.

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Quantum-chemical study on thermal transformations of urea in ethylene glycol

Cited by 12 publications

References 15 publications

Alcohol associates as catalysts of tautomeric transformations

Alcohol associates as catalysts of tautomeric transformations

Thermal transformations of urea in ethylene glycol: III. Transformation of 2-hydroxyethyl carbamate into ethylene carbonate

Reaction Mechanisms and Rate Constants of Auto‐Catalytic Urethane Formation and Cleavage Reactions

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