Alcohols, C9-11, branched and linear, ethoxylated

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

12-27 Apr 2012

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Guideline study but deficient due to inappropirate choice of test concentration

Qualifier:

according to guideline

Guideline:

OECD Guideline 112 (Dissociation Constants in Water)

Principles of method if other than guideline:

Titration method

GLP compliance:

yes (incl. QA statement)

pKa:

7.6

Temp.:

20 °C

Titration Data- Dissociation Constant

Vol. of Titrant (mL)	pH	Mean Vol (mL)	∆pH/∆V
0.00	6.63	0.03	9.60
0.05	7.11	0.08	9.20
0.10	7.57	0.13	10.20
0.15	8.08	0.18	18.20
0.20	8.99	0.23	11.40
0.25	9.56	0.28	7.80
0.30	9.95	0.33	3.40
0.35	10.12	0.38	0.40
0.40	10.14	0.43	3.60
0.45	10.32	0.48	0.00
0.50	10.32	0.53	0.40
0.55	10.34	0.58	-6.80
0.60	10.00	0.63	-3.80
0.65	9.81	0.68	-2.60
0.70	9.68	0.73	-8.60
0.75	9.25	0.78	-2.80
0.80	9.11	0.80	11.39

Titration Data- Dissociation Constant- C9-11 Alcohol Ethoxylate analysis with Formic Acid

Vol. of Titrant (mL)	pH	Mean Vol (mL)	∆pH/∆V
0.00	6.57	0.03	-7.20
0.05	6.21	0.08	-6.80
0.10	5.87	0.13	-5.40
0.15	5.60	0.18	-5.20
0.20	5.34	0.23	-4.60
0.25	5.11	0.28	-3.20
0.30	4.95	0.33	-2.40
0.35	4.83	0.38	-2.80
0.40	4.69	0.43	-1.80
0.45	4.60	0.48	-1.80
0.50	4.51	0.53	-1.00
0.55	4.46	0.58	-0.80
0.60	4.42	0.63	-1.20
0.65	4.36	0.68	-0.80
0.70	4.32	0.73	-0.80
0.75	4.28	0.78	-0.80
0.80	4.24	0.83	-0.60
0.85	4.21	0.88	-0.60
0.90	4.18	0.93	-0.60
0.95	4.15	0.98	0.00
1.00	4.15	1.03	-0.80
1.05	4.11	1.08	-0.80
1.10	4.07	1.13	-0.20
1.15	4.06	1.18	-0.40
1.20	4.04	1.23	-0.40
1.25	4.02	1.28	-0.20
1.30	4.01	1.33	-0.40
1.35	3.99	1.38	-0.20
1.40	3.98	1.43	-0.20
1.45	3.97	1.48	-0.20
1.50	3.96	1.53	-0.60
1.55	3.93	1.58	0.00
1.60	3.93	1.63	-0.40
1.65	3.91	1.68	-0.20
1.70	3.90	1.73	-0.40
1.75	3.88	1.78	-0.20
1.80	3.87	1.83	-0.20
1.85	3.86	1.88	-0.20
1.90	3.85	1.93	-0.20
1.95	3.84	1.98	-0.20
2.00	3.83	2.03	-0.20
2.05	3.82	2.08	-0.20
2.10	3.81	2.13	0.00
2.15	3.81	2.18	-0.20
2.20	3.80	2.23	-0.20
2.25	3.79	2.25	-

Formal Determination of pKa

The titration was repeated as in the pKa estimation stage by adding 0.05 mL of the titrant at a time until 0.40 mL of the acid had been added to the test solution. The pH of test solution observed at the point where the volume of titrant added was 0.10 mL (since titre volume of 0.075 could not be obtained) was then recorded as the pKa of the sample.

The pKa of C9-11 Alcohol Ethoxylate was therefore determined from the analysis as 7.6 ± 0.5. However due to the chemical instability suspected in the analysis (at pH above 10.34) the pKa obtained was deemed inconclusive and must therefore be interpreted with the chemistry of the material taken into consideration.

Reference 2

Endpoint:

dissociation constant

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance has no ionic structure

Description of key information

The substance has no ionic structure.

Additional information

Attempts were made to determine the pKa value of the substance in accordance with OECD guideline 112. However due to suspected chemical instability at pH above 10.34 the obtained pKa of 7.6 was deemed inconclusive.