Isobaric heat capacities of ethyl heptanoate and ethyl cinnamate at pressures up to 16.3 MPa

In this work, new experimental values for the isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate are presented at temperatures ranging from (305 to 387) K and under pressures up to 16.3 MPa. The relative expanded uncertainty of the isobaric molar heat capacity is estimated to be less than 1%. The isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate rise with the increasing temperature and fall with the increasing pressure. Based on the experimental findings in our work and from the literature, the isobaric molar heat capacities of saturated fatty acid methyl esters and fatty acid ethyl esters are found to rise with the carbon number, while the isobaric molar heat capacity of aromatic ester ethyl cinnamate is lower than that of the saturated fatty acid ethyl ester with the same or less carbon number due to the unsaturation. A correlation is proposed for the isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate with a maximum absolute relative deviation of 0.5%.