|
|||||
|
|
A quantum chemical study on the polycondensation reaction of polyesters: The mechanism of catalysis in the polycondensation reaction |
|
| Authors: | Isamu Shigemoto Tomonori Kawakami Mitsutaka Okumura |
| Affiliation: | a Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan b Advanced Materials Research Laboratories, Toray Industries, Inc., 2-1 Sonoyama 3-chome, Otsu, Shiga 520-0842, Japan c Composite Materials Research Laboratories, Toray Industries, Inc., 1515 Oaza-Tsutsui, Masaki-cho, Iyo-gun, Ehime 791-3193, Japan |
| Abstract: | We carried out a theoretical study on the mechanism of catalysis in the poly(ethylene terephthalate) (PET) polycondensation reaction. Transesterification reaction of diethylterephthalate with ethanol is investigated as a model system by using the B3LYP level of theory, and Sb(OEt)3, Ge(OEt)4 and Ti(OEt)4 are adopted as model catalysts. We found that the metal center of metal alkoxides coordinates to the carbonyl oxygen atom of the ester, and the alkoxy oxygen atom of alkoxy ligands attacks to the carbonyl carbon atom of the ester to form the four-centered transition state. The activation energy for tetraethoxy titanium catalyzed reaction in vacuo is 15.47 kcal/mol; this is comparable to the experimental result of 11.2 kcal/mol for poly(butylene terephthalate)/Ti(OBu)4. Because the other mechanisms gave much higher activation energies, this is the most convincing mechanism of PET polycondensation catalysis by antimony, germanium and titanium alkoxides. |
| Keywords: | Poly(ethylene terephthalate) Quantum chemistry Polycondensation catalysis |
| 本文献已被 ScienceDirect 等数据库收录！ | |