Polyesters bearing furan moieties. Part 3. A kinetic study of the transesterification of 2-furoates as a model reaction for the corresponding polycondensations

✍ Scribed by Khrouf, Amel; Boufi, Sami; El Gharbi, Rachid; Gandini, Alessandro

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 198 KB
• Volume: 48
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199908)48:8<649::aid-pi210>3.0.co;2-o

✦ Synopsis

The kinetics and mechanism of transesteri®cation reactions involving furanic esters (and aliphatic or aromatic counterparts for the sake of comparison) have been studied in detail using various catalysts and a wide range of experimental conditions. The purpose of this model investigation is to gather a thorough understanding of the process which simulates the corresponding syntheses of furanic polyesters. Whereas the orders in the two reagents was consistently unity, the order with respect to the catalyst varied from 0.5 to about unity as a function of increasing temperature and of the structure of the promoter used. In the case of Ti(OBu) 4 which was the catalyst most used, this behaviour was attributed to the existence of a monomer/dimer equilibrium of the catalyst molecules in the media selected for this work. The presence of the furan heterocycle produced a partial sequestration of the catalyst, through complexation induced by its dienic character, thus reducing the actual rate of transesteri®cation. The existence of this complex was inferred by using unreactive furans as retarding additives and shown by FTIR spectroscopy.