Extraction and Analysis of Eugenol from Cloves
Keywords:Cloves, Drug chemistry, Eugenol, Medical plants, GC-MS
This paper describes a laboratory procedure for the extraction and identification of eugenol from cloves (Syzygium aromaticum L.). The purpose is to instruct students in the isolation and identification of a medicinally relevant compound from a plant via simple solvent extraction. The analytical tools employed to identify eugenol and other naturally occurring chemical components in the cloves extract include color tests, thin layer chromatography (TLC), infrared spectrophotometry (IR), and gas chromatography coupled to mass spectrometry (GC-MS). In addition to eugenol, the cloves extract contains acetyl eugenol which can be distinguished from eugenol by several test methods. Triethylamine is used as a reagent at two different stages of testing. In the TLC analysis, triethylamine is used to basify the mobile phase which facilitates the separation of eugenol from acetyl eugenol. Optimizing separation parameters by TLC introduces the concept of method development. Additionally, the work prompts the discussion of concepts such as differential migration, interparticle forces, pKa, and surface basicity. In the GC-MS analysis, triethylamine is used with acetic anhydride to promote the quantitative conversion of eugenol into acetyl eugenol by removing acetic acid from the product side of the chemical equation. This provides an opportunity for instruction of concepts such as drug derivatization, chemical equilibria, and LeChatelier’s principle. Several other terpenes common to plant extracts can also be identified by GC-MS. The laboratory-based pedagogy is designed to be progressively complex to accommodate various educational levels from high school to post-secondary.
Copyright (c) 2021 James Vincent DeFrancesco
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