3,5,5-trimethylhexanoic acid

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study initiation date: 29 July 2009 Study completion date: 19 November 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adopted on 27 July 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

Directive 92/69/EEC, Official Journal L 383 A 1992

Deviations:

no

GLP compliance:

yes

Type of method:

flask method

Key result

Water solubility:

0.7 g/L

Temp.:

20 °C

pH:

3.8

Details on results:

See IUCLID section "Any other information on results incl. tables".

Details on measurements performed and corresponding results:

Sample no.	Amount of test item [mg]	Added volume of water [mL]	Shaking time at 30°C [h]	Analysed carbon concentration [mg C/L]	Concentration of the test item [g/L]^1)	pH value^2)
1	108	15	24	448	0.66	3.7
2	115	15	24	445	0.66	3.8
3	117	15	48	441	0.65	3.7
4	123	15	48	452	0.67	3.8
5	116	15	72	473	0.70	3.7
6	120	15	72	460	0.68	3.9

1) calculated from the carbon concentration of the sample solutions and the carbon content of the pure test item (67.7 %)

2) The purified water used for the tests had a pH value of 7.06.

Samples 1 to 6, descriptive statistical analysis:

Arithmetic mean value [g/L]: 0.67;

Standard deviation [g/L]: 0.02;

Relative standard deviation [%]: 2.67;

Conclusions:

Water Solubility (OECD 105): 0.7 g/L (at 20°C; pH 3.77)
Interpretation of results: moderately soluble (100-1000 mg/L)

Executive summary:

The water solubility of the test item was determined compliant with GLP according to OECD guideline no. 105 [adopted on 27 July 1995] and EU test method A.6 [Directive 92/69/EEC, Official Journal L 383 A 1992] with

the flask method. Test item concentrations were determined by carbon analysis (carbon content of the test item: 67.7%)

Independently from the incubation conditions applied (24, 48, or 72 h at 30°C), solubility at 20°C was always between 0.65 and 0.70 mg/L. The water solubility was therefore determined as the arithmetic mean over all six incubated samples:

Arithmetic mean value [g/L]: 0.67;

Standard deviation [g/L]: 0.02;

Relative standard deviation [%]: 2.67;

Mean pH: 3.77 (3.7 -3.9);

The valid and reliable study produced the following result for the water solubility of the submission substance:

Water solubility (at 20°C): 0.7 g/L (pH 3.77)

Description of key information

Water solubility (OECD 105): 0.7 g/L at 20°C (pH: 3.8)

Key value for chemical safety assessment

Water solubility:

0.7 g/L

at the temperature of:

20 °C

Additional information

The water solubility of the test item was determined compliant with GLP according to OECD guideline no. 105 [adopted on 27 July 1995] and EU test method A.6 [Directive 92/69/EEC, Official Journal L 383 A 1992] with the flask method. Test item concentrations were determined by carbon analysis (carbon content of the test item: 67.7%)

Independently from the incubation conditions applied (24, 48, or 72 h at 30°C), solubility at 20°C was always between 0.65 and 0.70 mg/L. The water solubility was therefore determined as the arithmetic mean over all six incubated samples:

Arithmetic mean value [g/L]: 0.67;

Standard deviation [g/L]: 0.02;

Relative standard deviation [%]: 2.67;

Mean pH: 3.77 (3.7 -3.9);

The valid and reliable study produced the following result for the water solubility of the submission substance:

Water solubility (at 20°C): 0.7 g/L (pH 3.77)

Based on a pKa of 4.8 determined for the submission substance, according to the Henderson-Hasselbach equation 91.5% of the dissolved fraction are in the non-dissociated state at pH 3.77. Accordingly, water solubility in the neutral pH range around pH 7.0 will be higher.

Supporting handbook data (Ullmann´s Encyclopedia of Industrial Chemicals, 1986) are available which report the water solubility for isomeric C9 acids (isononanoic acid) as 0.3 % (by weight) at 20 °C. This corresponds to 2.99 g/L based on the densitiy for 3,5,5-trimethylhexanoic acid. Data on pH are not available, but the higher water solubility reported here in comparison to the valid key study (factor of ca. 4.3) may well be due to a pH closer to the neutral range.