Registration Dossier

Diss Factsheets

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
November 20, 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
Remarks:
According to the ACD/pKa Web service provided by Advanced Chemistry Development, Inc. and it is not GLP.
Justification for type of information:
1. SOFTWARE
ACD/I-Lab Web service

2. MODEL (incl. version number)
ACD/pKa 8.03

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
(confidential)
Qualifier:
according to guideline
Guideline:
other: ACD/I-Lab Web service (ACD/pKa 8.03)
Deviations:
no
GLP compliance:
no
Dissociating properties:
no
No.:
#1
pKa:
15.63
No.:
#2
pKa:
13.98
No.:
#3
pKa:
-1.04

pKa1(HL/H+L;1)=15.63±0.10

pKa2(H2L/H+HL;4)=13.98±0.46

pKa3(H3L/H+H2L;4)=-1.04±0.70

Conclusions:
The nitrogen atom in the structure of the substance is protoned at pH -1.04 and below. At pH 13.98 the nitrogen atom is deprotonated and at pH 15.63 also the hydroxyl group. In the environmentally relevant pH range (pH4 to pH9) is the susbtance neutral form existing.
Executive summary:

The purpose of this study was to estimate the dissociation constant (pKa-values) of the susbtance.

In the environmentally relevant pH range (pH 4 to pH 9) of the susbtance is present in its neutral form and not dissociated or protonated. The pKas' of the substance have been calculated with the prediction module of ACD/I-Lab Web service (ACD/pka 8.03). The respective pKa's of the different possible forms have been predicted to be:

pKa=15.63±0.10

pKa=13.98±0.46

pKa=-1.04±0.70

Description of key information

In the environmentally relevant pH range (pH4 to pH9), the parent substance (amide) is in the neutral form (i.e. no pH-dependency).

Transformation products (carboxylates) are expected to be at least partially ionised.

Key value for chemical safety assessment

Additional information

The purpose of this study was to estimate the dissociation constant (pKa-values) of the substance.

The pKas of a representative major constituent of the substance have been calculated with the prediction module of ACD/I-Lab Web service (ACD/pka 8.03).

The nitrogen atom in the structure is protoned at pH -1.04 and below. At pH 13.98 the nitrogen atom is deprotonated and at pH 15.63 also the hydroxyl group. Therefore, no key value is relevant for the environmental assessment.

As supporting information, literature provides a pKa of 4.95 for lauric acid, which is an analogue of the expected transformation products. Therefore, these compounds are expected to be partially ionised in acidic medium, and totally ionised in alkaline conditions.

Categories Display