Computational determination of ring opening polymerization reaction mechanism of alpha-angelica lactone
Küçük Resim Yok
Tarih
2018
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Science Bv
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In the present study, we investigated the ring opening polymerization of alpha-angelica lactone (AL) catalyzed by the tin (II) 2-ethylhexanoate, Sn(Oct)(2) through the coordination insertion mechanism by employing the semi empirical PM6, PM6-D3H4, PM7, and the DFT-B3LYP, B3LYP-D2 and omega B97X-D methods in both gas and solvent (toluene, THE, DMF and DMSO) media. The DFT calculations revealed that the initiation stage consists of three steps; a stable complex formation, a low energy conformational transformation and the ring opening. NBO analysis was conducted to explain the interactions between the electrophilic and nucleophilic centers. The omega B97X-D method gives the closest result (30.2 kcal/mol) to the experimentally found activation barrier (26.3 kcal/mol) for this system. Therefore, omega B97X-D has the best performance among all the methods studied here. The mechanism of the addition of a new monomer to the active chain, which constitutes the propagation stage of the polymerization, was further investigated and, as expected, a lower barrier compared to that of the initiation stage was obtained (14.5 kcal/mol). The PCM calculations revealed that the solvent did not affect the activation barrier. In addition, the enthalpy of ring opening polymerization of alpha-angelica lactone was calculated based on the initiation and propagation stages and the thermodynamics of the system was discussed.
Açıklama
Anahtar Kelimeler
Poly(angelica lactone), Ring opening polymerization, Density functional theory, Tin(II) 2-ethylhexanoate, Biodegradable polymers, Transition state theory
Kaynak
Computational and Theoretical Chemistry
WoS Q Değeri
Q4
Scopus Q Değeri
Cilt
1142
