The effect of the side azole substitutes on extraction ability of the copolymers based on N-vinylamides

Abstract

The aim of this work is investigation of the influence of the nature of the side azole substitutes on the extraction ability of N-vinylcaprolactam (VC) /N-vinylformamide (VF) with N-vinylimadazole (VI), 1-vinyl-3,5-dimethylpyrazole (VDMP) and 1-methacryloyl-3,5-dimethylpyrazole (MDMP) copolymers in relation to essential α-amino acid histidine. The copolymers with different monomer content were synthesized by free radical copolymerization in dioxane solution with AIBN as inintiator. It was found that VC-VI and VF-VI copolymers are water soluble at all monomer content, and water solubility of the other polymers depends on VDMP and MDMP containing in the macro chain. VC-VDMP copolymers are water soluble below 0.25 mol frac VDMP containing, and VC-MDMP – below 0.05 mol frac MDMP containing. For VF-VDMP and VF-MDMP – below 0.25 and 0.07 mol frac VDMP and MDMP containing respectively.   All water soluble copolymers were used in two-phase water-salt extraction system with the using of ammonium sulphate as salting-out agent for histidine removing. It’s shown that the most efficient extragents are copolymers containing imidazole cycles as side substitutes due to its higher base property of the «pyridine» nitrogen atom compared to a pyrazole cycle. It’s established for VC-VI and VF-VI copolymers that extraction efficiency depends on content and size of the coils of the macromolecules in aqueous solutions. The degree of extraction R correlates with hydrodynamic radii R_h of the macromolecules. With increasing of the R_h values degree of extraction also increases. To sum up the extration ability of the copolymers containing different azole side substitutions in relation to histidine is researched