Registration Dossier
Registration Dossier
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EC number: 919-274-6 | CAS number: -
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
Data source
Materials and methods
Results and discussion
- Dissociating properties:
- ambiguous
Applicant's summary and conclusion
- Conclusions:
- While the pKa of the test material is expected to be low, the exceedinly low water solubility of either the acid or its sulfonate anion will not result in significant dissociation or give rise to any significant lowering of pH as a result.
- 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 272-473-4 (EINECS) is a highly oil soluble and potentially ionizable organic sulfonic acid of extremely low water solubility. Taken collectively, these properties suggest sufficient to warrant for 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, anywater solublefraction of sulfonate anion (parts per billion) will likely remain in equilibrium with its parent acid. The pKa of such alkaryl sulfonic acid is approximately 0.5. Thus, at typical physiological and environmental pHs, it is reasonable to expect that the sulfonate ion will dominate this acid-base equilibrium, and therefore slight pH changes, within the ranges normally considered important physiologically, environmentally, or for this particular analysis, will not significantly alter the position of this equilibrium with respect to acid-base pairing.
Apart from the sulfonic acid 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
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