2-phosphonobutane-1,2,4-tricarboxylic acid

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

other: Reasoning based on basic scientific (chemical) knowledge for aqueous solutions.

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

Reasoning based on basic scientific (chemical) knowledge for aqueous soultions.

GLP compliance:

not specified

Details on results:

As indicated in the OECD Screening Information DataSet (SIDS) for the High Production Volume Chemical "PBTC", the water-based acid is "completely miscible" in water.

For comparison's sake, the solubility in water of the non-water based acid was calculated by means of the program, which is part of the program compilation EPI Suite. The chemical structure of the pure acid structure was entered by SMILES (Simplified Molecular Input Line Entry System) notations. The resulting solubility is 6.555e+005 mg/L (655 g/L) at 25°C (program WSKOW v1.14).

Conclusions:

Interpretation of results: miscible
The water-based acid is "completely miscible" in water.

Executive summary:

The water-based acid is "completely miscible" in water. ). As the substance is marketed as a 50% water solution, it is considered scientifically not reasonable to conduct further tests on water solubility.

Reference 2

Endpoint:

water solubility

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

2-Phosphonobutane-1,2,4-tricarboxylic acid is the non-charged parent compound containing three carboxylic acid functionalities and a phosphonate moiety. To form Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate these carboxylic acids, as well as one OH-functionality of the phosphonate moiety, are deprotonated according to their pKa values with sodium hydroxide. The solid substance tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate can be obtained by drying the aqueous solution.
In aqueous conditions, both compounds dissociate to form the common compound for read-across purposes. This rationale is supported by QSAR estimations for the dissociation constants pKa of the relevant deprotonation steps.
Please find the Justification attached to Chapter 13.2.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

909.2 g/L

Conc. based on:

test mat.

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

pH:

6

Remarks on result:

completely miscible

Details on results:

The test items forms, dissolved in water, a jellylike mass. This makes it difficult to measure volumes. In a preliminary test a quantity of 200.5 mg test item was soluble in 0.2 mL water which is equivalent to 1000 g/L. A subsequent test in the ratio of 5 g test item and 5 g water also showed a clear phase. A test with 10 g test item and 1 g water showed a two phased system (jellylike phase/solid phase). Therefore, the solubility was assumed to be between 1000 g/L and 10000 g/L.

Due to the properties of the test item and the solubility test solutions no value in mass per volume was achievable. Instead a solubility value in g/g was achieved (content of test item per gram of solubility test solution). In Addition, the density of the test solutions was determined to convert the result into the unit “g/L”. The density is determined at 1.55235 g/mL.

Due to the properties of the test item and the solubility test solutions no value in mass per volume was achievable. Instead a solubility value in g/g was achieved (content of test item per gram of solubility test solution).

Results of individual determinations and mean value

Water solubility test at 20 °C	Flask A    [g/100g]		Flask B      [g/100g]		Flask C      [g/100g]		Mean value
Test	1	2	1	2	1	2	-
Concentration of Tetrasodium hydrogen 2-phosphonatobutane- 1,2,4-tricarboxylate	57.43	58.47	57.92	57.60	59.91	60.11	58.6 g/100g
pH-Value	6		6		6		-

The relative standard deviation between the single determinations is < 15 % (RSD = 2.0 %).

The validity criteria have therefore been met.

In Addition, the density of the test solutions was determined to convert the result into the unit “g/L”. The density is determined at 1.55235 g/mL.

The water solubility of Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate in demineralized water at 20 °C is determined to be:

58.6 g/100 g of the test solution (test item and demin. water)

Remark: The used terminology “/100 g test solution” refers to the mixture of dissolved test item and demineralized water. Due to the known content of the test item and the fact that no other components are added, the water content can be calculated as the difference.

Therefore, the result of the test can also be stated as a solubility of the test item of 58.6 g in 41.4 g of demin. water (equal to 1415 g test item per 1000 g water.

Conclusions:

Water solubility of the test material Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate at 20 °C was determined as: 909.2 g/L

Executive summary:

Water solubility of the test material Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate was investigated at 20 °C with the shake flask method at 20 °C according to OECD Guideline 105. was determined as: 909.2 g/L

Description of key information

As there is no data available for 2-phosphonatobutane-1,2,4-tricarboxylate acid a read-across approach with the corresponding salt tetrasodium hydrogen 2-phosphonobutane-1,2,4-tricarboxylic is proposed.

In aqueous media, tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate and 2-phosphono-butane-1,2,4-tricarboxylic acid dissociate into the corresponding anion (2-phosphonatobutane-tricarboxylate ion) and the sodium ion and hydrogen ion (proton), respectively. Fate, behavior and the ecotoxicological properties of 2-phosphonobutane-1,2,4-tricarboxylic acid and its tetrasodium salt are thought to be an effect of the phosphonato-carboxylate ion rather than of the sodium ion or the hydrogen ion (proton), which are normal constituents in environmental systems and have no relevant ecotoxic properties in low concentrations.

Therefore a read-across between 2-phosphono-butane-1,2,4-tricarboxylic acid and tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate is justified.

Water solubility of the test material Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate was investigated at 20 °C with the shake flask method at 20 °C according to OECD Guideline 105. was determined as: 909.2 g/L

Key value for chemical safety assessment

Water solubility:

909 g/L

at the temperature of:

20 °C