Development of a New Route for Separating and Purifying 4-Ethyl-2-methoxyphenol Based on the Reaction Mechanism between the Chemical and Calcium Ion

Based on the characteristic that Ca2+ can react with 4-ethyl-2-methoxyphenol (EMP) to form a complexation with a phenol–calcium ratio of 4:1, a new extraction and purification method of EMP is developed for the first time in this work. At an optimum purification condition, 99.60% purity of EMP can be obtained through a reaction and decomposition operation. By combining a variety of characterizations, which consist of in situ Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance (NMR), inductively coupled plasma optical emission spectrometer (ICP-OES), gas chromatography–mass spectrometry (GC–MS)/flame ionization detector (FID), elemental analysis, and thermogravimetric analysis, the reaction mechanism of the coordination process is studied. It is demonstrated that there are three stages of the coordination reaction between Ca2+ and EMP. A neutralization reaction occurs in the first stage, while the second stage is a mixing reaction stage including neutralization and coordination reaction. When the reaction proceeds to the third stage, another coordination reaction occurs. Furthermore, phenol and ethanol are added as impurities in EMP. EMP with a purity of more than 99.50% can be obtained using this purification method. It confirms that this efficient method can achieve a good purification effect even for EMP solutions with complicated components.