Chemical transformations of succinic acid recovered from fermentation broths by a novel direct vacuum distillation-crystallisation method

A novel alternative methodology (direct crystallisation) to the traditional calcium precipitation to
obtain succinic acid (SA) from defined and wheat-based fermentation broths is reported. SA
crystals were successfully recovered from fermentation broths (FB) using this method. A higher
SA crystal purity (95%) and yield (70%) were obtained in the direct crystallisation method
compared to a slightly modified traditional calcium precipitation method (90% and 24%,
respectively). Chemical transformations (e.g. esterifications) to high-added value derivatives of
both recovered SA crystals were then investigated using a range of solid acids including our acidic
tunable mesoporous carbonaceous materials denoted as StarbonR acids. Results showed that SA
crystals could be successfully converted into mono- and diesters in high yields and selectivities
employing solid acids regardless of the reaction conditions. The order of reactivity was found to
be: pure SA crystals > SA crystals from defined FB > FB SA crystals. Results demonstrate that
SA can be effectively purified from actual fermentation broths, showing the importance of
integrating the fermentation and downstream processing to optimise the fermentative production
of SA and its chemical transformations to produce high-added value derivatives.