Reaction mass of tetrasodium [μ-[[4,4'-[(3,3'-dihydroxy[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[3-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicuprate(4-) and hydrogen [[4,4'-[(3,3'-dihydroxy[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[3-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicuprate(4-)

Partition coefficient

Description of key information

logKow = - 4.0319

Key value for chemical safety assessment

Log Kow (Log Pow):

-4.032

at the temperature of:

20 °C

Additional information

Direct Blue 080:1 is a multiconstituent substance composed by the acidic and the sodium salt forms of the same structure (58.44 % and 13.55 % of the substance respectively).

Partition coefficient was determined by OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method. The test was performed on the sodium salt of the Direct Blue 080:1 and the partition coefficient results to be – 4.0319. Moreover, EPI Suite v4.10 has been used in order to compare the two structures. The two results, derived from estimation of partition coefficient by means of KOWWIN v1.68 estimate, are -3.28 for the sodium salt and 0.88 for the acidic form.

The smile notations used for the estimations are:

Sodium salt

O=S(=O)(O[Na])c2ccc3c1N=Nc4ccc(cc4O[Cu]Oc1c(cc3c2)S(=O)(=O)O[Na])c5ccc6N=Nc7c(O[Cu]Oc6c5)c(cc8cc(ccc78)S(=O)(=O)O[Na])S(=O)(=O)O[Na]

Acidic Form

O=S(=O)(O)c2ccc3c1N=Nc4ccc(cc4O[Cu]Oc1c(cc3c2)S(=O)(=O)O)c5ccc6N=Nc7c(O[Cu]Oc6c5)c(cc8cc(ccc78)S(=O)(=O)O)S(=O)(=O)O

 

Considering the high similarity between the two estimated values and the composition of the substance, Direct Blue 080:1 is expected to have the same partition coefficient of the sodium salt form as described by the experimental data (- 4.0319).