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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-dioxinsDichlorodibenzo-p-dioxinsTrichlorodibenzo-p-dioxinsTetrachlorodibenzo-p-dioxins
Molecular mass218.6253.1287.5322
Density (g/dm3)No dataNo dataNo data1.827
Melting point (┬░C)89.0-105.5114-210128-163175-306
Boiling point (┬░C)No dataNo data374 446.5
Soil sorption coefficient (log Koc)No dataNo dataNo dataNo data
Octanol/Water Partition  (log Kow)4.52-5.455.86-6.396.86-7.456.6-8.7
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*10-49.0*10-7-2.9*10-66.46*10-8-7.5*10-77.4*10-10-4*10-3
HenryÔÇÖs law coefficient (KH) atm*m3/mol82.7*10-6-146.26*10-621.02*10-6-80.04*10-637.9*10-67.01*10-6-101.7*10-6
Pentachlorodibenzo-p-dioxinsHexachlorodibenzo-p-dioxinsHeptachlorodibenzo-p-dioxins

Oktachlorodibenzo-
p-dioxins

Molecular mass356.4390.9425.3459.8
Density (g/dm3)No dataNo dataNo dataNo data
Melting point (┬░C)195-206238-286265330-332
Boiling point (┬░C)No dataNo data507.2485-510
Soil sorption coefficient (log Koc)No dataNo dataNo dataNo data
Octanol/Water Partition  (log Kow)8.64-9.489.19-10.49.69-11.388.78-13.37
Solubility in water in 25 ┬░C (mg/dm3)1.18*10-4 4.42*10-6 2.4*10-6-1.9*10-32.27*10-9-7.4*10-8
Vapour pressure at 25 ┬░C (mm Hg)6.6*10-103.8*10-115.6*10-12-7.4*10-88.25*10-13
HenryÔÇÖs law coefficient (KH) atm*m3/mol2.6*10-644.6*10-61.31*10-6-2.18*10-56.74*10-6