Introducing Organic Chemistry Students to Natural Product Isolation Using Steam Distillation and Liquid Phase Extraction of Thymol, Camphor, and Citral, Monoterpenes Sharing a Unified Biosynthetic Precursor

Plants have provided and continue to provide the inspiration and foundation for modern medicines. Natural product isolation is a key component of the process of drug discovery from plants. The purpose of this experiment is to introduce first semester undergraduate organic chemistry students, who have relatively few lab techniques at their disposal, to the process of natural product isolation. In one, 3 h lab period, students use steam-distillation and liquid-phase extraction to isolate a single medicinally relevant molecule from one of three plants. The identity of the molecule can be demonstrated using infrared spectroscopy and thin-layer chromatography. Students choose to isolate thymol from thyme (Thymus vulgaris), citral from lemongrass (Cymbopogen), or camphor from sagebrush (Artemisia tridentata)three commercially available plants with a long history of use. Each isolated molecule has a common biosynthetic origin in the plant, and this is discussed to introduce the relationship between organic chemistry and biochemistry.