Reaction mass of 2-{[2-(2-hydroxyethoxy)ethoxy]carbonyl}benzoic acid and 2,2'-oxydiethanol

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Guideline:

other: REACH guidance on QSARs R.6, May 2008

Principles of method if other than guideline:

ACD 7.0 software program for estimating the dissociation constant (pKa) in water.The recommended method, “apparent constants, approximated”, was used for the estimation. The program was developed by Advanced Chemistry Development Inc.
90 Adelaide Street West, Toronto, Ontario, M5H 3V9, Canada (http://www.acdlabs.com); Copyright © 1994-2003; Build: 18 April 2003

GLP compliance:

no

Dissociating properties:

yes

No.:

#1

pKa:

14.32

Temp.:

25 °C

Remarks on result:

other: HL/H+L

No.:

#2

pKa:

3.35

Temp.:

25 °C

Remarks on result:

other: H2L/H+HL

1. Defined endpoint: Dissociation constant (pKa) in water

2. Unambiguous algorithm: For 2-{[2-(2-hydroxyethoxy)ethoxy]carbonyl}benzoic acid the following fragment descriptors (parent compound) were identified as reaction centres:HO-C-Rand R-C-COOH

3. Applicable domain: The identified reaction centers have been found as fragments in the Internal Reaction Centers Database with experimental equations. The substance only contains32 atoms, which is much less than the limit of ACD/pKa DB of 255.The substance only contains two ionization centres with one fragment for each.The substance does not contain the atoms, what are not accepted by ACD/pKa DB. The fragment that occurs in the structure of 2-{[2-(2-hydroxyethoxy)ethoxy]carbonyl}benzoic acid applied by the program is verified by the user. The rules applied for the substance appears appropriate. An individual uncertainty for the investigated substance is not available.

4. Statistical characteristics: Each calculation from ACD/pKa DB is provided with its 95 % confidence interval and, when available, literature references with experimental results. The accuracy of calculations for simple structures is usually better than ±0.2 pKa units (for complex structures it is better than ±0.5 pKa units).

5. Mechanistic interpretation: The mechanistic basis of the model is the linear free energy relationship (LFER), which is an empirical correlation between the standard free energies of reaction or activation for two series of reactions, both subjected to the same variations in reactant structures or reaction conditions. As applied to the estimation of acid dissociation constants, the LFER is basically a substituent-effect approach.

6. Adequacy of prediction: The result for 2-{[2-(2-hydroxyethoxy)ethoxy]carbonyl}benzoic acid falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:

The dissociation constants for the test item are estimated to be pKa1 of 14.32 and pKa2 of 3.35.

Executive summary:

The dissociation constants of the test item were estimated by ACD/pKa DB included in ACD/labs 7.00 Release. According to the estimated results, this substance presents mainly as non-ionic form under environmentally relevant pH5 - 9.

Reference 2

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Guideline:

other: REACH guidance on QSARs R.6, May 2008

Principles of method if other than guideline:

ACD 7.0 software program for estimating the dissociation constant (pKa) in water.The recommended method, “apparent constants, approximated”, was used for the estimation. The program was developed by Advanced Chemistry Development Inc.
90 Adelaide Street West, Toronto, Ontario, M5H 3V9, Canada (http://www.acdlabs.com); Copyright © 1994-2003; Build: 18 April 2003

GLP compliance:

no

Dissociating properties:

yes

No.:

#1

pKa:

14.75

Temp.:

25 °C

Remarks on result:

other: HL/H+L

No.:

#2

pKa:

14.03

Temp.:

25 °C

Remarks on result:

other: H2L/H+HL

1.Defined endpoint:Dissociation constant (pKa) in water

2.Unambiguous algorithm:For 2 -(2 -hydroxyethoxy)ethan-1-ol the following fragment descriptors (parent compound) was identified as reaction centres: HO-C-R

3. Applicable domain:The identified reaction centers have been found as fragments in the Internal Reaction Centers Database with experimental equations. The substance only contains 17 atoms, which is much less than the limit of ACD/pKa DB of 255.The substance only contains two ionization centres with one fragment for each.The substance does not contain the atoms, what are not accepted by ACD/pKa DB. The fragment that occurs in the structure of 2 -(2 -hydroxyethoxy)ethan-1 -ol applied by the program is verified by the user. The rules applied for the substance appears appropriate. An individual uncertainty for the investigated substance is not available.

4. Statistical characteristics:Each calculation from ACD/pKa DB is provided with its 95 % confidence interval and, when available, literature references with experimental results. The accuracy of calculations for simple structures is usually better than ±0.2 pKa units (for complex structures it is better than ±0.5 pKa units).

5. Mechanistic interpretation:The mechanistic basis of the model is the linear free energy relationship (LFER), which is an empirical correlation between the standard free energies of reaction or activation for two series of reactions, both subjected to the same variations in reactant structures or reaction conditions. As applied to the estimation of acid dissociation constants, the LFER is basically a substituent-effect approach.

6. Adequacy of prediction:The result for 2 -(2 -hydroxyethoxy)ethan-1 -ol falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:

The dissociation constants for the test item are estimated to be pKa1 of 14.75 and pKa2 of 14.03.

Executive summary:

The dissociation constants of pKa1 of 14.75 and pKa2 of 14.03 were estimated by ACD/pKa DB included in ACD/labs 7.00 Release. According to the estimated results, this substance presents mainly as non-ionic form under environmentally relevant pH5 - 9.

Description of key information

Th test item consists of two main components. The dissociation constants for one of the main component (CAS 111-46-6)  are estimated to be pKa1 of 14.75 and pKa2 of 14.03. For the other main component (CAS 2202-98-4) dissociation constants of  pKa1 of 14.32 and pKa2 of 3.35 were calculated.

Key value for chemical safety assessment

pKa at 20°C:

14.03