Related Experiment Video
Updated: May 11, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Aldol addition of dihydroxyacetone to N-Cbz-3-aminopropanal catalyzed by two aldolases variants in microreactors
Martina Sudar1, Zvjezdana Findrik, Durđa Vasić-Rački
1University of Zagreb, Faculty of Chemical Engineering and Technology, Department of Reaction Engineering and Catalysis, Savska cesta 16, 10 000 Zagreb, Croatia.
Abstract:
Aldol addition of dihydroxyacetone to N-Cbz-3-aminopropanal catalyzed by two d-fructose-6-phosphate aldolase variants, FSA A129S and FSA A129S/A165G, overexpressed in Escherichia coli was studied in microreactors. The presence of organic solvent was necessary due to poor solubility of N-Cbz-3-aminopropanal in water. Hence, three co-solvents were evaluated: ethyl acetate, acetonitrile and dimethylformamide (DMF). The influence of these solvents and their concentration on the enzyme activity was independently tested and it was found that all solvents significantly reduce the activity of FSA depending on their concentration. The reaction was carried out in three different microreactors; two without and one with micromixers. By increasing enzyme concentration, it was possible to achieve higher substrate conversion at lower residence time. Enzyme activity measured at the outlet flow of the microreactor at different residence time revealed that enzymes are more stable at lower residence times due to shorter time of exposure to organic solvent. The reaction in the batch reactor was compared with the results in microreactor with micromixers. Volume productivity was more than three fold higher in microreactor with micromixers than in the batch reactor for both aldolases. It was found to be 0.88Md(-1) and 0.80Md(-1) for FSA A129S and FSA A129S/A165G, respectively.
Related Concept Videos
Acid-Catalyzed Aldol Addition Reaction
Base-Catalyzed Aldol Addition Reaction
C–C Bond Formation: Aldol Condensation Overview
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
C–C Bond Cleavage: Retro-Aldol Reaction
In the first step, as depicted in Figure 1, the base deprotonates the β-hydroxy ketone at the hydroxyl group to form an alkoxide ion.
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...

