Process intensification of continuous-flow imine hydrogenation in catalyst-coated tube reactors

Hydrogenation of an imine (N-Cyclohexyl(benzylidene)imine) into a secondary amine (N-Benzylcyclohexylamine) was studied in catalyst-coated tube reactors to utilize the advantages of continuous-flow processes. Tetrahydrofuran (THF) was found to be an optimal solvent providing high reaction and low catalyst deactivation rates compared to toluene and isopropanol. Even in THF, however, the deactivation was noticeable, with a decrease in the imine hydrogenation rate of 80 and 47% during 20 h on stream over the Pd/C and Pd/SiO2 catalyst-coated tubes, respectively. After comparing various regeneration methods, we found that washing with isopropanol recovered the catalyst activity. The catalyst support affected regeneration: the Pd/SiO2 catalyst suffered from a permanent degradation, whereas the Pd/C was stable over multiple reaction-regeneration cycles. Process intensification study at a range of reaction temperatures allowed to establish the optimal secondary amine production temperature of 110 °C. The long-term stability test under the optimized conditions allowed reaching a turnover number (TON) of 150 000, an unprecedented value in heterogeneous imine hydrogenation. A reductive amination cascade reaction (aldehyde and amine condensation simultaneously with imine hydrogenation) showed the byproduct yield below 3%. The cascade reaction, however, decreased the reaction throughput by 45% compared to the direct imine hydrogenation still allowing for a throughput of 0.75 kg of product per day in a single 5 m catalyst-coated reactor opening a way for a multikilogram synthesis

Novel ketone diet enhances physical and cognitive performance.

Ketone bodies are the most energy-efficient fuel and yield more ATP per mole of substrate than pyruvate and increase the free energy released from ATP hydrolysis. Elevation of circulating ketones via high-fat, low-carbohydrate diets has been used for the treatment of drug-refractory epilepsy and for neurodegenerative diseases, such as Parkinson's disease. Ketones may also be beneficial for muscle and brain in times of stress, such as endurance exercise. The challenge has been to raise circulating ketone levels by using a palatable diet without altering lipid levels. We found that blood ketone levels can be increased and cholesterol and triglycerides decreased by feeding rats a novel ketone ester diet: chow that is supplemented with (R)-3-hydroxybutyl (R)-3-hydroxybutyrate as 30% of calories. For 5 d, rats on the ketone diet ran 32% further on a treadmill than did control rats that ate an isocaloric diet that was supplemented with either corn starch or palm oil (P < 0.05). Ketone-fed rats completed an 8-arm radial maze test 38% faster than did those on the other diets, making more correct decisions before making a mistake (P < 0.05). Isolated, perfused hearts from rats that were fed the ketone diet had greater free energy available from ATP hydrolysis during increased work than did hearts from rats on the other diets as shown by using [31P]-NMR spectroscopy. The novel ketone diet, therefore, improved physical performance and cognitive function in rats, and its energy-sparing properties suggest that it may help to treat a range of human conditions with metabolic abnormalities.-Murray, A. J., Knight, N. S., Cole, M. A., Cochlin, L. E., Carter, E., Tchabanenko, K., Pichulik, T., Gulston, M. K., Atherton, H. J., Schroeder, M. A., Deacon, R. M. J., Kashiwaya, Y., King, M. T., Pawlosky, R., Rawlins, J. N. P., Tyler, D. J., Griffin, J. L., Robertson, J., Veech, R. L., Clarke, K. Novel ketone diet enhances physical and cognitive performance.A.J.M. thanks the Research Councils UK for supporting his Academic Fellowship. This work was supported by the Defense Advanced Research Projects Agency.This is the final version of the article. It first appeared from FASEB at https://doi.org/10.1096/fj.201600773R

Mechanochemical synthesis of TiO2/NiFe2O4 magnetic catalysts for operation under RF field

Composite NiFe2O4–TiO2 magnetic catalysts were prepared by mechanochemical synthesis from a mixture of titania supported nickel ferrite nanoparticles and P25 titania (Evonic). The former provides fast and efficient heating under radiofrequency field, while the latter serves as an active catalyst or catalyst support. The highest heating rate was observed over a catalyst prepared for a milling time of 30 min. The catalytic activity was measured over the sulfated composite catalysts in the condensation of aniline and 3-phenylbutyric acid in a stirred tank reactor and in a continuous RF heated flow reactor in the 140–170 °C range. The product yield of 47% was obtained over the sulfated P25 titania catalyst in the flow reactor

Radical 1,4-aryl transfer in arylcarboxamides leading to phthalimides, biaryls and enantiomerically enriched beta-arylethylamines

5-exo Cyclisation of vinyl-, aryl- and alkyl-radicals onto the aryl group of arylcarboxamides is followed by β-scission of the resulting spirocyclohexadienyl radicals with ejection of a carbamoyl radical. The fate of this radical depends on the substrate but, in the cases studied, either 5-endo cyclisation or direct reduction follows to give phthalimides, biaryls or β-arylethylamines. © 2008 Elsevier Ltd. All rights reserved