Abstract
Biodiesel is a promising alternative diesel fuel obtained from vegetable oils, animal fats, or waste oils by transesterifying the oil or fat with an alcohol such as methanol. In an extension of previous work, fiber‐optic near infrared spectroscopy was used to quantitatively monitor the transesterification reaction (6‐L scale) of a vegetable oil (soybean oil) to methyl soyate. The results were correlated with 1H nuclear magnetic resonance spectroscopy. The method described here can be applied to the transesterification of other vegetable oils.