A Comprehensive Evaluation of the Density of Neat Fatty Acids and Esters

Density is one of the most important physical properties of a chemical compound, affecting numerous applications. An application in the case of fatty acid esters (biodiesel) is that density is specified in some biodiesel standards. In the present work, the density of fatty acid methyl, ethyl, propyl, and butyl esters as well as triacylglycerols in the C8–C24 range was determined in the range of 15–40 °C with a densitometer utilizing the oscillating U‐tube technique. Literature data on density are compiled and compared, showing that data for these compounds are incomplete with discrepancies existing in some cases. Besides known effects such as density decreasing with increasing chain length and increasing saturation, it is shown that trans fatty compounds exhibit lower density than cis fatty compounds. Density data for several saturated odd‐numbered, C18, as well as C20 and C22 polyunsaturated fatty esters are reported for the first time. The density contribution of compounds with high melting points is predicted. An equation is given for the calculation of the density of mixtures.