Properties
In the pure form, PCDDs are colorless solids or crystals. 2,3,7,8-TCDD is odourless. The odours of the other PCDDs are not known.
| Monochlorodibenzo-p-dioxins | Dichlorodibenzo-p-dioxins | Trichlorodibenzo-p-dioxins | Tetrachlorodibenzo-p-dioxins | |
| Molecular mass | 218.6 | 253.1 | 287.5 | 322 |
| Density (g/dm3) | No data | No data | No data | 1.827 |
| Melting point (°C) | 89.0-105.5 | 114-210 | 128-163 | 175-306 |
| Boiling point (°C) | No data | No data | 374 | 446.5 |
| Soil sorption coefficient (log Koc) | No data | No data | No data | No data |
| Octanol/Water Partition (log Kow) | 4.52-5.45 | 5.86-6.39 | 6.86-7.45 | 6.6-8.7 |
| Solubility in water in 25 °C (mg/dm3) | 0.278-0.417 | 3.75*10-3-1.67*10-2 | 4.75*10-3-8.41*10-3 | 7.9*10-6-6.3*10-4 |
| Vapour pressure at 25 °C (mm Hg) | 9.0*10-5-1.3*10-4 | 9.0*10-7-2.9*10-6 | 6.46*10-8-7.5*10-7 | 7.4*10-10-4*10-3 |
| Henry’s law coefficient (KH) atm*m3/mol | 82.7*10-6-146.26*10-6 | 21.02*10-6-80.04*10-6 | 37.9*10-6 | 7.01*10-6-101.7*10-6 |
| Pentachlorodibenzo-p-dioxins | Hexachlorodibenzo-p-dioxins | Heptachlorodibenzo-p-dioxins |
Oktachlorodibenzo- |
|
| Molecular mass | 356.4 | 390.9 | 425.3 | 459.8 |
| Density (g/dm3) | No data | No data | No data | No data |
| Melting point (°C) | 195-206 | 238-286 | 265 | 330-332 |
| Boiling point (°C) | No data | No data | 507.2 | 485-510 |
| Soil sorption coefficient (log Koc) | No data | No data | No data | No data |
| Octanol/Water Partition (log Kow) | 8.64-9.48 | 9.19-10.4 | 9.69-11.38 | 8.78-13.37 |
| Solubility in water in 25 °C (mg/dm3) | 1.18*10-4 | 4.42*10-6 | 2.4*10-6-1.9*10-3 | 2.27*10-9-7.4*10-8 |
| Vapour pressure at 25 °C (mm Hg) | 6.6*10-10 | 3.8*10-11 | 5.6*10-12-7.4*10-8 | 8.25*10-13 |
| Henry’s law coefficient (KH) atm*m3/mol | 2.6*10-6 | 44.6*10-6 | 1.31*10-6-2.18*10-5 | 6.74*10-6 |