Thermal Behavior of n-Octanol and Related Ether Alcohols

Abstract

The thermal behavior of n-octanol and related ether alcohols has been studied by differential scanning calorimetry (DSC). The melting point, heat of fusion, and isobaric heat capacities of n-octanol obtained from the DSC measurements are in good agreement with literature values. The ether alcohols display kinetic barriers for forming a solid phase during cooldown. These barriers are least for 6-methoxyhexanol that forms a solid upon cooling except for the highest measured temperature change rate of 40 K·min^-1, followed by 4-propoxybutanol that forms a solid during cooldown only at low cooling rates. 2-Pentoxyethanol and 5-ethoxypentanol form a solid during the heating cycle that then melts again upon further heating. 3-Butoxypropanol does not display any exo- and endothermic features for all measured temperature change rates. Consequently, new data on melting point and heats of fusion are reported for the ether alcohols except for 3-butoxypropanol. New isobaric heat capacities are presented as well for the liquid phase of these ether alcohols.

Figure 1

Cooling curves (red) and heating curves (black) obtained for n-octanol (a), 2-pentoxyethanol (b), 3-butoxypropanol (c), 4-propoxybutanol (d), 5-ethoxypentanol (e), and 6-methoxyhexanol (f) at a temperature change rate of 10 K·min^–1.

Figure 2

Heating curves of n-octanol at 10 K·min^–1 (dark blue), 5 K·min^–1 (green), and 2 K·min^–1 (red).

Figure 3

Heating curves of 6-methoxyhexanol at 40 K·min^–1 (pink), 20 K·min^–1 (light blue), 10 K·min^–1 (dark blue), 5 K·min^–1 (green), and 2 K·min^–1 (red).

Figure 4

Cooling curves of 4-propoxybutanol at 40 K·min^–1 (pink), 20 K·min^–1 (light blue), 10 K·min^–1 (dark blue), 5 K·min^–1 (green), 2 K·min^–1 (red), and 1 K·min^–1 (black).

Figure 5

Cooling curves of 6-methoxyhexanol at 40 K·min^–1 (pink), 20 K·min^–1 (light blue), 10 K·min^–1 (dark blue), 5 K·min^–1 (green), and 2 K·min^–1 (red).

Figure 6

heating curves of 2-pentoxyethanol at 10 K·min^–1 (dark blue), 5 K·min^–1 (green), 2 K·min^–1 (red), and 1 K·min^–1 (black).

Figure 7

Heating curves of 4-propoxybutanol at 40 K·min^–1 (pink), 20 K·min^–1 (light blue), 10 K·min^–1 (dark blue), 5 K·min^–1 (green), 2 K·min^–1 (red), and 1 K·min^–1 (black).

Figure 8

Heating curves of 5-ethoxypentanol at 40 K·min^–1 (pink), 20 K·min^–1 (light blue), 10 K·min^–1 (dark blue), 5 K·min^–1 (green), 2 K·min^–1 (red), and 1 K·min^–1 (black).

Figure 9

Molar isobaric heat capacity (C_p) of n-octanol as a function of temperature, comparing results from this study (solid line) with data from van Miltenburg et al. (squares), Dzida (circles), Pokorný et al. (triangle-up), Vesely et al. (triangle-down), and Fulem et al. (diamonds), Cline and Andrews (cross), Páramo et al. (plus), Naziev et al. (triangle-left), Anouti et al. (triangle right).