Triboron trimethyl hexaoxide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 October 2017 to 25 October 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Sponsor and 10037-115-5
- Expiration date of the lot/batch: 06 June 2019
- Purity test date: 06 June 2017

Radiolabelling:

no

Analytical monitoring:

no

Test performance:

To 100 mL water (Tap water purified by a Milli-Q water purification system (Millipore, Bedford, MA, USA), actual pH 6.05), 820 µL test item (i.e. 1 gram using a density of 1.219 g/mL) was added using a pipette. White flakes appeared immediately and started to dissolve.
After 5 minutes of stirring, the flakes had dissolved and pH no longer decreased with time. The pH had become 5.49. Addition of an extra volume of 820 µL test item, showed the same effect (white flakes that dissolved within 5 minutes) and resulted in a pH of 4.98.
Based on this, it was concluded that Trimethoxyboroxine (TMBX) hydrolysed
instantaneously when added to water and that the hydrolysis product dissolved within 5
minutes.
Half-life time of Trimethoxyboroxine (TMBX) is therefore reported to be <5 minutes. Actual
temperature of the test solution was 19.0 ± 0.4°C.

Transformation products:

yes

No.:

#1

No.:

#2

Details on hydrolysis and appearance of transformation product(s):

White flakes appeared immediately and started to dissolve.
After 5 minutes of stirring, the flakes had dissolved and pH no longer decreased with time. The pH had become 5.49. Addition of an extra volume of 820 µL test item, showed the same effect (white flakes that dissolved within 5 minutes) and resulted in a pH of 4.98.

Key result

Temp.:

19 °C

DT50:

< 5 min

Details on results:

To 100 mL water (Tap water purified by a Milli-Q water purification system (Millipore, Bedford, MA, USA), actual pH 6.05), 820 µL test item (i.e. 1 gram using a density of 1.219 g/mL) was added using a pipette. White flakes appeared immediately and started to dissolve.
After 5 minutes of stirring, the flakes had dissolved and pH no longer decreased with time. The pH had become 5.49. Addition of an extra volume of 820 µL test item, showed the same effect (white flakes that dissolved within 5 minutes) and resulted in a pH of 4.98.
Based on this, it was concluded that Trimethoxyboroxine (TMBX) hydrolysed instantaneously when added to water and that the hydrolysis product dissolved within 5 minutes.
Half-life time of Trimethoxyboroxine (TMBX) is therefore reported to be <5 minutes. Actual temperature of the test solution was 19.0 ± 0.4°C.
Because the sponsor supplied the information that boric acid would be formed when the test item was added to water, it was tested whether the concentration of boric acid formed might be derived from the pH measured. To 100 mL water, subsequently amounts of 0.7136, 0.7131 and 0.7140 g Boric acid (Merck, Darmstadt, Germany) were added. At the start and after each addition, pH was measured and [H+] was calculated. [H+] at the beginning of the test was 6.92 ^10-7 mol/L (pH 6.16). After addition of 0.7136 gram boric acid, it was
1.02 ^10 -5 mol/L (pH 4.99). [H+] after addition of an additional amount of 0.7131 gram boric acid, it became 2.75 ^10-5 mol/L (pH 4.56). After addition of an additional amount of 0.7140 gram boric acid, [H+] was 5.01^10-5 mol/L (pH 4.30). Though additions were very similar, changes in [H+] were not similar. Based on this it was concluded that it is not possible to correlate change in pH with concentration boric acid formed.

Temperature changes were recorded but were not significant and can therefore not be used for more accurate determination of half-life time.

Validity criteria fulfilled:

not applicable

Conclusions:

Since it is not possible to develop a method for analysis of TMBX due to the quick hydrolysis and since pH cannot be used as a measure for the hydrolysis products formed, it is technically not possible to determine hydrolysis rate and half life time more accurately. Half-life time of Trimethoxyboroxine (TMBX) is therefore reported to be <5 minutes. Actual temperature of the test solution was 19.0 ± 0.4°C. Temperature changes were recorded but were not significant and can therefore not be used for more accurate determination of half-life time.

Description of key information

The hydrolysis half-life time of Trimethoxyboroxine (TMBX) is reported to be <5 minutes at a test solution temperature of 19.0 ± 0.4°C.

It was not possible to develop a method for analysis of TMBX due to the quick hydrolysis of the substance and since pH cannot be used as an accurate measure of the hydrolysis products formed, it is technically not possible to determine hydrolysis rate and half life time more accurately.  Temperature changes were recorded but were not significant and can therefore not be used for more accurate determination of half-life time.

Key value for chemical safety assessment

Half-life for hydrolysis:

5 min

at the temperature of:

19 °C