[No public or meaningful name is available]

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements. This model is validated for the test item tested. The QSAR model SPARC was validated for compounds having one until 8 ionization sites and all organic compound except : covalent hydrates ,tautomers, carbon acid reaction center where the perturbations for this group are very large, quaternary amines. The test item isn't part of this kind of compounds and the test item has five possible ionization sites.

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Principles of method if other than guideline:

QSAR estimation

GLP compliance:

not specified

Dissociating properties:

yes

No.:

#1

pKa:

12.03

Temp.:

25 °C

Predicted value (model result):see the attach illustration

Predicted value (comments):No comments

Input for prediction:SMILES

 

Applicability domain

 Domains:The SPARC chemical reactivity models have been designed and parameterized to be portable to any chemical reactivity property and any chemical structure. 

The SPARC pKa calculator was trained on 2500 organic molecules, then validated on 4338 pKa’s (4550 including carbon acid) in water. The calculator was tested for multiple ionization’s up to the 6th (simple organic molecules) and 8th (azo dyes) for molecules with multiple ionization sites. A lot of organic molecules used to validate SPARC, the compounds for which SPARC don’t have used are :

1.  covalent hydrates ( multiple in-ring N compounds example)

2.  tautomers (example methyl-substituted imidazole)

3. Carbon acid reaction center where the perturbations for this group are very large, and the measurement standard deviation is not better than 1 unit. For example, the pKa’s for methane, nitro-methane, tri-nitro-methane are 52, 10, 3.6, respectively. (SPARC calculates the pKa for carbon acid within ± 1.3 pKa units).

4. quaternary amines.

The test item had 5 ionization sites and isn’t part of the four categories above. So the test item fall into the applicability domain of SPARC.

Conclusions:

The test item has one pka: pKa= 12.03. At environmental pH (5 to 9), the test item is on un-ionized form.

Executive summary:

The prediction of constant dissociation was estimated using a recommended QSAR model : SPARC (October 2011 release w4.6.1691-s4.6.1687). This QSAR was validated for compounds having between 1 and 8 ionization sites. A lot of organic molecules used to validate SPARC, the compounds for which SPARC don’t have used are :

1.  covalent hydrates ( multiple in-ring N compounds example)

2.  tautomers (example methyl-substituted imidazole)

3. Carbon acid reaction center where the perturbations for this group are very large, and the measurement standard deviation is not better than 1 unit. For example, the pKa’s for methane, nitro-methane, tri-nitro-methane are 52, 10, 3.6, respectively. (SPARC calculates the pKa for carbon acid within ± 1.3 pKa units).

4. quaternary amines.

The test item had 5 ionization sites and isn’t part of the four categories above. So the test item fall into the applicability domain of SPARC.

The test item has one pka : pka = 12.03. At environmental pH (5 to 9), the test item is on un-ionized form.

Reference 2

Endpoint:

dissociation constant

Type of information:

not specified

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No test substance information, no guideline, secondary literature, but reference database according to Guidance on information requirements and chemical safety assessment Chapter R.7.A.

Principles of method if other than guideline:

No data

GLP compliance:

not specified

Dissociating properties:

yes

No.:

#1

pKa:

4.65

Remarks on result:

other: experimental results (reference SERJEANT,EP & DEMPSEY,B (1979))

No data

Conclusions:

pKa of methacrylic acid is 4.65. At environmental pH (5 to 9), the test item is on ionized form with one or no negative charge.

Executive summary:

pKa of methacrylic acid is 4.65. At environmental pH (5 to 9), the test item is on ionized form with one or no negative charge.

Description of key information

Estimated pKa (by QSAR calculation) at 25°C of N-[2-(2-oxoimidazolidin-1-yl)ethyl]methacrylamide : 12.03 
Experimental pKa of methacrylic acid  : 4.65

Additional information

The test item is composed of two main constituents who have dissociable groups : N-[2-(2-oxoimidazolidin-1-yl)ethyl]methacrylamide and methacrylic acid.

The determination of the dissociation constant for N-[2-(2-oxoimidazolidin-1-yl)ethyl]methacrylamide was performed by a QSAR (SPARC), recommended in Guidance on information requirements and chemical safety assessment Chapter R.7.A.. This compound has basic properties and a pka of 12.03 at 25°C

The dissociation constant of methacrylic acid was found in a database recommended by ECHA guidance document on information requirements. This compound is an acid and has a pka of 4.65.

So at environmental pH (5 to 9), methacrylic acid can be on un-ionized or ionized form with one negative charge and N-[2-(2-oxoimidazolidin-1-yl)ethyl]methacrylamide is on un-ionized form.