Production of a room temperature ionic liquid using a microwave reactor

This laboratory is a simple introduction to the use of the CEM Discover microwave reactor as well as a demonstration of nucleophilic substitution. The product produced is a novel room temperature ionic liquid (RTIL) called HMIM iodide for 1-hexyl-3-methylimidazolium iodide.

PROCEDURE

To a 10 ml microwave tube equipped with a stirbar is added 1-iodohexane (2.2 mmol) and 1-methylimidazole (2.0 mmol). The tube is capped and heated at time and temperature assigned in the classroom. Typical times are 2 – 8 minutes with temperatures in the 70 – 140 °C range.

After cooling to room temperature, the samples are washed with about 2 ml of ethyl acetate. The ionic liquid is removed with a glass pipet and stored in a small vial for further investigation. Note: in low temperature and/or low time reaction conditions, it is possible that not enough product formed to produce a layer after addition of ethyl acetate. If that is the case, discard the wash layer and record the outcome.

Prelab questions

1. What is the mass (in g) of 2.2 mmol 1-iodohexane?

2. What is the volume (in µl) of 2.2 mmol 1-iodohexane?

3. What is the mass (in g) of 2.0 mmol 1-methylimidazole?

4. What is the volume (in µl) of 2.0 mmol 1-methylimidazole?

Reference

Varma, R. S.; Namboodiri, V. V. Solvent-free preparation of ionic liquids using a household microwave oven. Pure Appl. Chem. 2001, 73, 1309-1313.