abstract
This work addresses the effect of chaotropic anions (thiocyanate and tosylate) on the solubility of glycine, L-leucine, L-phenylalanine, and L-aspartic acid in aqueous solutions at 298.2 K. The salts used were NaSCN, KSCN, NH4SCN, and NaC7H7SO3 (sodium tosylate), with salt concentrations ranging from 0 to 2 molal. The pH of the saturated solutions was registered, and solid-phase studies were also performed. All the thiocyanate salts and sodium tosylate induced a salting-in effect, except in the systems composed of glycine in aqueous sodium tosylate solutions at 0.5 and 1 molal. For L-leucine, L-phenylalanine, and L-aspartic acid the salting effect of anions followed the order tosylate(-)> SCN-> NO3- > Cl-, in good agreement with the behavior predicted by the Hofmeister series. Differently, the relative solubility of glycine in aqueous nitrate solutions was higher than in those containing thiocyanate, followed by the chloride and, closing the rank, the solutions containing the tosylate anion, suggesting that the solubility change in this case is achieved by a different mechanism.
keywords
AQUEOUS SALT-SOLUTIONS; POLYMORPHIC TRANSFORMATION; MOLAR VOLUMES; ASPARTIC ACID
subject category
Chemistry
authors
Aliyeva, M; Brandao, P; Coutinho, JAP; Ferreira, O; Pinho, SP
our authors
Mehriban Aliyeva
Collaborator
Paula Cristina Ferreira da Silva Brandão
Assistant Researcher
Simão Pedro de Almeida Pinho
CollaboratorProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was developed within the scope of the project CIMO-Mountain Research Center, UIDB/00690/2020 and LA/P/0007/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Mehriban Aliyeva thanks FCT and European Social Fund (ESF) for her Ph.D. grant (SFRH/BD/139355/2018).