Measurement and Correlation of Solubility of Theobromine, Theophylline, and Caffeine in Water and Organic Solvents at Various Temperatures

The solubility of theobromine, theophylline, and caffeine in water and five organic solvents including methanol, ethanol, 1-propanol, ethyl acetate, and acetone was determined by a high performance liquid chromatography method at <i>T</i> = (288.15 to 328.15) K and atmospheric pressure. It was found that the solubility of theobromine, theophylline, and caffeine in these solvents increased with increasing temperature. The empirical Apelblat equation and universal quasichemical model were used to correlate the experimental solubility. The results showed that both models can satisfactorily correlate the solubility data. The crystal forms of the solutes in equilibrium with the saturated solution were analyzed using scanning electron microscopy and powder X-ray diffraction

Reactive Extraction of Levulinic Acid from Aqueous Solutions Using Trioctylamine with Diluents 2‑Ethyl-1-hexanol, 4‑Methylpentan-2-one, and Isoamyl Alcohol

Separating carboxylic acids from aqueous solutions is a challenge, and reactive extraction has been examined as an attractive alternative. This study investigates the reactive extraction of levulinic acid (LA) using trioctylamine (TOA) in various diluents, such as 2-ethyl-1-hexanol, 4-methylpentan-2-one (MIBK), and isoamyl alcohol. For this purpose, liquid–liquid equilibrium (LLE) data was experimentally obtained for the mix of LA + TOA + H2O + diluents at T = 293.15 K and atmospheric pressure. From the obtained data, the ability of various TOA/diluent mixtures was evaluated in terms of distribution coefficient (KD). Isoamyl alcohol was found to be an effective diluent at the diluted region (wLAaq KD value of 9.4. However, increasing the concentration of LA resulted in approximately the same extraction ability as the other tested diluents with TOA. Furthermore, the nonrandom two-liquid (NRTL) excess Gibbs energy model was applied to correlate the tie lines. The root-mean-square deviations (RMSD) in liquid mass fraction obtained with the NRTL model for the experimental data of the above-mentioned different LLE systems of 2-ethyl-1-hexanol, MIBK, and isoamyl alcohol were 0.013, 0.018, and 0.016, respectively. Additionally, the KD values of the systems were also computed