Microwave Extraction of Eugenol from Cloves: A Greener Undergraduate Experiment for the Organic Chemistry Lab

Brittany J Crouse,Emily L Vernon,Stella Kim,Melinda C Box,Maria T Gallardo-Williams,Brittany A Hubbard

doi:10.12691/wjce-7-1-3

Abstract

The extraction of eugenol from cloves is a frequent experiment in organic chemistry labs at the sophomore level. In this paper, the commonly used steam distillation procedure has been modified to use microwave extraction. This change resulted in a simplified procedure, a reduction in the amount of sample required, and an increase in the efficiency of the extraction of eugenol from dried cloves. These modifications led to reduction of waste and energy use. Variations of the solvent composition, solvent volume, and amount of cloves were tested. It was found that a 50/50 v/v mixture of ethanol and water with whole cloves produced satisfactory results at the undergraduate laboratory level for the selective extraction of eugenol with 1g of whole cloves in less time than steam distillation.

Highlights

Of all the experiments routinely performed in organic chemistry labs, those involving the extraction of essential oils from vegetable matter have been part of the repertory of chemical educators for many years; the extraction of oil from cloves is a classic example
Yields are better with dichloromethane, but since n-pentane is a safer solvent and the amounts isolated are enough for infrared spectroscopy (IR) characterization, we suggest it as a viable alternative
This experiment was designed to produce an alternative to steam distillation which is the traditional undergraduate laboratory method used for obtaining eugenol from cloves [6]

Summary

Introduction

Of all the experiments routinely performed in organic chemistry labs, those involving the extraction of essential oils from vegetable matter have been part of the repertory of chemical educators for many years; the extraction of oil from cloves is a classic example. Procedures for the steam distillation of oil from cloves abound [5,6] and several modifications such as extraction with liquid carbon dioxide [7], and extraction using pressurized hot water with a commercial espresso machine [8] have been recently described. Both studies attempt to circumvent the use of steam distillation, and aim to design a greener version of the experiment. Compared to the original steam distillation, the modifications presented here make it possible to complete the experiment in less time, using reduced amounts of reagents, and generating less waste

Methods

Results

Conclusion