Preferential solvation of azoxystrobin in binary solvent mixtures of (methyl alcohol + ethyl ethanoate) and ( n -propyl alcohol + ethyl ethanoate)

The preferred solvation conditions δ x 1,3 of the natural fungicide compound azoxystrobin in two mixed binary methyl alcohol solvents (1) + ethyl ethanoate (2) and n -propyl alcohol (1) + ethyl ethanoate were calculated using the inverse Kirkwood–Buff integrals approach based on the reported solubility data (2). δ x 1,3 values vary nonlinearly with the co-solvent (1) proportion in all the binary mixtures. The preferential solvation magnitude of azoxystrobin by the co-solvent is highest in {methyl alcohol (1) + ethyl ethanoate (2)} mixtures and lowest in n -propyl alcohol (1) + ethyl ethanoate (2). For the methyl alcohol (1) + ethyl ethanoate (2) systems, δ x 1,3 values are negative in mixes high in ethyl acetate and co-solvents but positive in intermediate compositions. Though, for the n -propyl alcohol (1) + ethyl ethanoate mixtures with composition 0.55 < x 1 < 1, the δ x 1,3 are positive values, indicating that azoxystrobin is preferentially solvated by co-solvent. For the two co-solvent mixtures, maximum solvations are near to x 1 = 0.35–0.55 which can be attributed to the disordered structure of ethyl ethanoate molecules around the non-polar azoxystrobin moieties.