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5. A continuous flow process for the green and sustainable production of N-alkyl imidazoles

Author

Fekete Melinda, Kocsis Lászlo, Dormán György, Jones Richard V., and Darvas Ferenc

Subjects
continuous flow, high pressure flow reactor zeolite, high temperature, ionic liquid, n-alkyl imidazoles, Chemistry, QD1-999
Abstract

N-alkyl imidazoles are the basic components of the widely used and studied imidazolium ionic liquids. The need for these materials multiplied since the field of ionic liquids has been gaining more and more importance. Our aim was to develop a continuous flow method for the N-alkylation of imidazole that provides the alkylated derivatives with high productivity and selectivity, using only cheap, preferably green starting materials. Herein, we report a novel method for the preparation of N-alkyl imidazoles over a zeolite catalyst using high temperature and pressure in a heterogeneous catalytic flow reactor. The yield and selectivity exceeded 95% for n-chain alcohols while the residence time was kept at 13 min, thus, the productivities were between 9 g/h and 14 g/h. The only side product in the reaction is water, thus, the process expresses high atom economy.

Published
2016
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10. An innovative route for the production of atorvastatin side-chain precursor by DERA-catalysed double aldol addition

Author

European Commission, 0000-0002-5312-8951, 0000-0002-0247-4483, Švarc, Anera, Fekete, Melinda, Hernández, Karel, Clapés Saborit, Pere, Findrik Blažević, Zvjezdana, Szekrenyi, Anna, Skendrović, Dino, Vasić-Rački, Đurđa, Charnock, Simon J., Presečki, Ana Vrsalović, European Commission, 0000-0002-5312-8951, 0000-0002-0247-4483, Švarc, Anera, Fekete, Melinda, Hernández, Karel, Clapés Saborit, Pere, Findrik Blažević, Zvjezdana, Szekrenyi, Anna, Skendrović, Dino, Vasić-Rački, Đurđa, Charnock, Simon J., and Presečki, Ana Vrsalović

Abstract

A multi-enzyme route for the production of an atorvastatin side-chain was proposed. The approach includes the consecutive double aldol addition of acetaldehyde to the phenylacetamide amino-protected propanal by 2-deoxyribose-5-phosphate aldolase (DERA), the oxidation by ketoreductase, the lipase-catalysed acylation and amino group deprotection by penicillin G-acylase. To explore the feasibility of the process, the DERA reaction was studied into detail. Based on the kinetic and stability studies, a mathematical model was developed and validated in a batch and fed-batch reactor. The highest productivity was obtained in repetitive batch reactor (229.1 g/(L day)). The highest final product concentration of 124 g/L was obtained in fed-batch reactor. The mathematical model-based optimisation provided insight into the possibilities for process metrics improvement. Further, the second step was explored. The results showed that the DERA reaction and the oxidation reaction can be carried out as the multi-enzyme one pot process in the sequential manner.

Published
2021

15. Treatments of Lignocellulosic Hydrolysates and Continuous‐Flow Hydrogenation of Xylose to Xylitol.

Author

Fehér, Anikó, Fehér, Csaba, Rozbach, Margaréta, Rácz, Gergely, Fekete, Melinda, Hegedűs, László, and Barta, Zsolt

Subjects
XYLITOL, HYDROLYSIS, XYLOSE, HYDROGENATION, CATALYSIS
Abstract

Abstract: Xylitol is produced by the heterogeneous catalytic hydrogenation of xylose over Raney nickel. The hydrogenation must typically be followed by several purification steps, which makes the chemical production relatively complex and expensive. In this study, activated carbon and bio‐purification treatments of corn stover hydrolysates and subsequent nickel‐catalyzed hydrogenation of xylose to xylitol were investigated. The activated carbon treatment was used to eliminate inhibitory compounds and increase the efficiency of the bio‐purification step. It was found that the glucose could be completely eliminated from the hydrolysate. The hydrogenation reactions of corn stover hydrolysate demonstrated that a high reaction temperature resulted in high sugar alcohol yields and selectivity. At a given temperature, the flow rate had no significant effect on xylitol yield. [ABSTRACT FROM AUTHOR]

Published
2018
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