Phosphorodithioic acid, mixed O,O-bis(sec-Bu and 1,3-dimethylbutyl) esters, zinc salts

Dissociation constant

Administrative data

Endpoint:

dissociation constant

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Results and discussion

Dissociating properties:

no

Applicant's summary and conclusion

Conclusions:

The test material is already in a dissociated state. No other associated functionalities are capable of further dissociation. Therefore a waiver is appropriate.

Executive summary:

Dissociation Constant

Justification For data Waiving (ECHA TGD ref 7.1.17)

 

 

From the compositional description and the structural formula given, it can be concluded that this substance 272-238-5 (EINECS) is a highly oil soluble and fully ionized organo-metallic salt having poor low water solubility. Taken collectively, these properties may seem counter intuitive but are nonetheless sufficient to warrant a data waiver according to the assessment criteria normally applied during the evaluation of this physical property. 

 

In the gut of animals and in typical aquatic environments, any water soluble fraction of dithiophosphate salt (parts per thousand) will likely remain in its original ionic state according to the well understood equilibrium for this salt and its conjugate acid. The pKa of such dialkyl-dithiophosphate esters is approximately 0.5. Thus, at typical physiological and environmental pHs, it is reasonable to expect that the free phosphate ester salt species will dominate this acid-base equilibrium. Therefore slight pH changes, within the ranges normally considered important physiologically or for this analysis in particular, will not significantly impact the stated position of this equilibrium with respect to acid-base pairing.

 

Apart from the dithiophosphate functional group present, there are no other indicative structural alerts that would indicate that this substance should be considered ionizable by any other means according to the sense of the meaning of the guidance given for assessing this endpoint. This empirical evaluation is furthermore confirmed by long term handling experience.

 

 

 

 

 

 

 

Dr. Thomas F. Buckley III