Continuous-flow alcohol protection and deprotection reactions catalyzed by silica-supported sulfonic acid
Berg, Sebastiaan A. van den; Frijns, Raoul A.M. ; Wennekes, Tom ; Zuilhof, Han - \ 2015
Journal of Flow Chemistry 5 (2015)2. - ISSN 2062-249X - p. 95 - 100.
Alcohol protection and deprotection - Catalysis - Continuous flow - Packed bed - Silyl ether
Alcohol protection and deprotection reactions, catalyzed by solid-supported sulfonic acid, have been investigated under continuous-flow conditions. Primary, secondary, benzylic and phenolic alcohols can be protected under these conditions by tetrahydropyranyl and several silyl ether moieties, generating synthetically useful amounts of material in short time. Furthermore, the described setup can be used to deprotect protected alcohols and be used in selective protection reactions. Because the solid-supported acid catalyst is continually reused in a packed-bed approach, workup is greatly simplified and in most cases only solvent removal is necessary, while reaching high turn-over numbers.
Channeled monoliths for selective recovery of a lacto-tripeptide from a crude hydrolyzate
Rodriguez-Illera, Marta ; Janssen, A.E.M. ; Boom, R.M. - \ 2015
Separation and Purification Technology 156 (2015)2. - ISSN 1383-5866 - p. 288 - 298.
Adsorption process - Monoliths - Packed bed - Plugging - Pressure drop - Process integration
Adsorption processes using a packed bed reactor are often used for the purification of nutraceuticals. However, when dealing with untreated streams, this leads to fouling and consequent increase in pressure drop. This work compares the use of channeled monoliths, "honeycomb" structures, with a packed bed, both made of the same type of activated carbon. The intrinsic permeability and performance of both structures during the adsorption of a bioactive peptide from a crude hydrolyzate were studied. Breakthrough experiments were performed on both types of systems under similar conditions. The results showed similar productivity and dynamic adsorptive capacity for both structures at comparable linear velocity and residence time, but the packed bed showed a strong pressure drop increase during column saturation, revealing plugging of the column, especially at high velocities (short residence times). The channeled monoliths did not present any significant pressure drop increase, and were able to operate at high velocities which increase the range of application for these types of processes.