| Autor: |
Gorji, Zahra Eshaghi, Khodadadi, Abbas Ali, Riahi, Siavash, Repo, Timo, Mortazavi, Yadollah |
| Předmět: |
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| Zdroj: |
Journal of the Taiwan Institute of Chemical Engineers; Nov2021, Vol. 128, p176-186, 11p |
| Abstrakt: |
• A series of metal-free, simple and low-cost organocatalysts showed very good activities towards CO 2 cycloaddition reaction. • A mechanism for cycloaddition reaction was proposed with the help of ESI-TOF. • The kinetic of reaction and activation energy were studied. • Synergistic effects were observed between hydrogen bond-donor (HBD) and halide ion of the catalytic systems. • The results demonstrate the versatile applicability of the catalytic systems for cycloaddition of various epoxides with CO 2 at mild conditions. Carbon dioxide is a versatile, non-toxic, and renewable C1 building block source to produce valuable chemicals such as cyclic carbonates. The purpose of this research is development of efficient, metal-free and affordable catalysts for cycloaddition reaction of CO 2 with epoxides at mild conditions. In the present work, a group of novel bifunctional organocatalysts consisting of different hydrogen-bond donors (HBDs) and halogen ion is simply synthesized. Under the optimized conditions, the reaction is kinetically and thermodynamically studied. Additionally, the catalytic active species are determined, and a mechanism is proposed with the help of electrospray‐ionization time‐of‐flight mass spectrometry (ESI-TOF MS). The most active catalytic system is obtained by chemically interaction of 3-bromopropionic acid (BPA) with DMF at 80 °C (BPA-DMF). An excellent product yield of 98% and a high TOF value are obtained with 0.99 mol% of BPA-DMF, which is attributed to the synergistic effects of carboxyl functional groups and halide ions. The activation energy was found to be 50.75 kJ/mol. The positive value of Gibbs free activation energy (ΔG‡) and negative value of activation entropy (ΔS‡) confirm a non-spontaneous, endergonic and kinetically controlled reaction. [Display omitted] [ABSTRACT FROM AUTHOR] |
| Databáze: |
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