RESEARCH NOTE pubs.acs.org/IECR
Solubilities of Pimelic Acid in Ionic Liquids Hua Li,†,* Juan Liu,† Daokui Tang,‡ and Hongkai Wang† † ‡
School of Chemical and Energy Engineering, Zhengzhou University, Zhengzhou, Henan 450001, People’s Republic of China The 58th Research Institute, CETC, Wuxi, Jiangsu 214035, People’s Republic of China
bS Supporting Information ABSTRACT: The solubilities of pimelic acid in ionic liquids [EMIM][HSO4], [PMIM]Br, [i-PMIM][HSO4], [BMIM]Br, and[BMIM][HSO4] are determined with the suitable experimental methods and apparatus. The experimental data of solubilities are correlated with the Apelblat equation. The solubilities correlated by the model are in good agreement with experimental data.
’ INTRODUCTION 1,7-Heptanediol is an important pharmaceutical intermediate and chemical material with wide use and good application prospect, more importantly, 1,7-heptanediol is the main raw material to synthesize 1,7-dibromoheptane. In the traditional methods, brominating agents are usually present with PBr3 or HBr or NaBr or n-bromosuccinimide (NBS) or dimethylbromosulfonium bromide (DMBS), etc. However, these methods have many disadvantages, such as pollution to the environment, difficulty in product separation, and corrosion to the equipment. To solve the aforementioned problems, we have developed a new technique1,2 for the synthesis of 1,7-heptanediol, using the raw material of pimelic acid and the solvent of ionic liquid [EMIM][HSO4] or [PMIM]Br or [i-PMIM][HSO4] or [BMIM]Br or [BMIM][HSO4]. Ionic liquid [EMIM][HSO4] or [PMIM]Br or [i-PMIM][HSO4] or [BMIM]Br or [BMIM][HSO4] is extensive in use and abundant in source; especially, the melting point of each satisfies the operated conditions in this experiment. In the brominating reaction, it is used as the brominating agent, catalyst, and solvent. The reaction is green, with mild conditions and a high yield, and the ionic liquid is easily regenerated and recycled. This new technique is characterized using a nonvolatile solvent, avoiding toxicity and corrosion of traditional halogenated agents, also with a high product purity and yield. In the synthesis and purification process of 1,7-heptanediol, it is very important to know the solubilities of pimelic acid in solvents, because the solubilities of pimelic acid in solvents directly influence the reaction rate and product yield. Therefore, in this study, the solubilities of pimelic acid in [EMIM][HSO4], [PMIM]Br, [i-PMIM][HSO4], [BMIM]Br, and [BMIM][HSO4] are determined and correlated with the Apelblat equation, and the solubilities that are correlated using the Apelblat model show good agreement with the experimental data. ’ EXPERIMENTAL SECTION
water and other volatile compounds. Decomposition of the roomtemperature ionic liquids (RTILs) was not observed under the experimental conditions. The water mass fraction of the dried RTILs is determined through Karl Fisher titration, and it is found to be
