Oil baths are typically employed as heating elements when the temperature must be carefully controlled and when the reactants are flammable (and thus an open flame is not advised). In this case, an oil bath was likely employed since THF is flammable. The oil is heated on a hot plate and the temperature is monitored using a thermometer. Specialized equipment may include an immersion heating circulator, which evenly circulates heat throughout the vessel. Materials used in oil baths include medical paraffin, glycerol, silicon oil, cottonseed oil, or mineral oil. Disadvantages of using an oil bath include potentially spilling or spattering the oil and the extended amount of time needed to sufficiently heat the oil.

 

University of Wisconsin, Madison Department of Chemistry. http://www.chem.wisc.edu/areas/organic/orglab/tech/oilbath.htm (accessed April 4, 2014).

 

Gelosa, D.; Sliepcevich, A. Chemical Laboratory Techniques; Milan, Italy, 2002; pp 4-5.