High-Pressure Density Measurements and Modeling of Hydrocarbons: 1-Hexene, 2, 4-Dimethylhexane, 2,2,4-Trimethylpentane, and n-Heptane.

UNLABELLED: Liquid densities of the hydrocarbons 1-hexene, 2,4-dimethylhexane, 2,2,4-trimethylpentane, and n-heptane were measured over a wide range of temperatures (293.15 K to 393.15 K) and pressures (up to 120 MPa), substantially extending the state range covered by previously available literature data. The density data were modeled using both an empirical correlation as well as a molecular-based equation of state (EOS). For each substance, an empirical Tammann-Tait correlation was developed that reproduces the new measurements with an average absolute deviation (AAD) of about 0.01%. Comparison with literature data shows good agreement for all four substances. Liquid densities calculated from the SAFT-VR Mie EOS were benchmarked against both the new data and literature data, yielding deviations typically below 0.4% which supports the predictive capability of this EOS across the studied conditions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s10765-026-03823-6.