Evaluation of Distribution and Partition Coefficients of Levulinic Acid in Octanol-Water System at 298.15 K

Abstract

Levulinic acid is a promising building block chemical with various applications, such as in pharmaceuticals and cosmetics. The key parameters used for assessing the environmental fate, risk assessment and toxicity of a compound in these applications include partition and distribution behavior of the compound. The partition and distribution coefficients can be measured from the ratio of the compound concentration in 1-octanol to the concentration in water at equilibrium. In this study, the distribution and partition behavior of levulinic acid in octanol-water system were determined experimentally using a simple and inexpensive shake flask approach according to OECD 107 via UV–Vis spectroscopy at 298.15 K. The neat and mutually saturated solvents were applied in the determination of distribution and partition behavior. The distribution coefficient (log D) using neat solvents (octanol-water) and saturated solvents (octanol_{(water−saturated)}-water_{(octanol−saturated)}) were determined, and the partition coefficient (log P) was calculated accordingly based on the relationship between log D and log P for weakly acidic compounds. In octanol-water and octanol_{(water−saturated)}-water_{(octanol−saturated)} system, the log D of levulinic acid were determined to be − 0.574 and − 0.816, while the log P were − 0.554 and − 0.790, respectively. The precision of the method was established with variation in the measurement less than 0.03 for both log D and log P. The negative value of log P indicates the preference of levulinic acid for the water phase over the octanol phase. The results from this study can be comprehended in product formulation and design related to levulinic acid as well as assessing the environmental fate.