Phase Diagram of Benzene to 35 kbar

The phase diagram of benzene has been determined to 35 kbar. Two triple points, liquid-benzene I–benzene II and liquid-benzene II–benzene III, have been located. These triple points are at 12 ± 0.5 kbar and 204 ± 5°C, and 22.5 ± 0.5 kbar and 335 ± 5°C, respectively. The benzene I–benzene II phase boundary is slightly convex towards the temperature axis. We were unable to locate the boundary separating the fields of benzene II and benzene III; thus the coordinates of the upper triple points were estimated entirely from the break in slope of the melting curve. Above 40 kbar and 580°C benzene disassociates.