Transesterification step optimization

It was found that ROP of TMC (first step) and LEA (second step) allowed for the preparation of A-B-A triblock copolymers without significant transesterification. The optimization of the temperature and reaction time were decisive for the success of this approach. ... 

Other metals which catalyze PET polycondensation are proposed to coordinate with and activate ester carbonyl groups similarly. That different metals are optimal for activating the ester carbonyls of DMT and of BHET (i.e., catalyzing transesterification and polycondensation, respectively) has been well explained by accounting for differences in carbonyl oxygen basicity between methyl esters and hydroxyethyl/alkoxyethyl esters. The optimum catalysts for each step maximize electronic interactions with the reacting esters [29, 30]. 

The results demonstrate that the two-step transesterification represents a suitable reaction system for a heterogeneously catalyzed RD process. The catalyst screening shows that there are several heterogeneous catalysts available to produce EMC and DEC, with sufficient yields for this application. Optimal operational conditions can be identified based on appropriate selectivity studies. 

Sarantopoulos, I., et al., 2014. Optimization of biodiesel production from waste lard by a two-step transesterification process imder mild conditions. Energy for Sustainable Development 23, 110—114. Available at http //www.sciencedirect.com/science/article/pii/... 

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