Trichloro(N,N-dimethyloctylamine)boron

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 14th July and 14th October 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The sample solutions were taken from the water bath at various times and the pH of each solution recorded.

Buffers:

Specification of Buffer Solutions:
The test system uses sterile buffer solutions at pH’s 4.0, 7.0 and 9.0.

Buffer solution (pH) Components Concentration (mol dm-3)
4 Potassium hydrogen phthalate 0.05
7 Disodium hydrogen orthophosphate (anhydrous) 0.03
Potassium dihydrogen orthophosphate 0.02
Sodium chloride 0.02
9 Disodium tetraborate 0.01
Sodium chloride 0.02

These commercial buffer solutions were diluted to 20% v/v with purified water, subjected to vacuum filtration through 0.2 µm filters, ultrasonication and then degassing with nitrogen to minimize dissolved oxygen content.

Details on test conditions:

Preparation of the Test Solutions:
The three sample solutions were prepared in stoppered glass flasks at a nominal concentration of 3.0 x 10E-4 g/L in the corresponding three diluted buffer solutions. 1% v/v acetonitrile was used as co-solvent to aid solubility.

The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the estimated water solubility.

The test solutions were split into individual vessels for each data point. The solutions were shielded from light whilst maintained at the test temperature.

Tier 2
Testing was undertaken at pH 4, pH 7 and pH 9. The solutions were maintained at 25.0 ± 0.5 °C, 35.0 ± 0.5 °C and 15.0 ± 0.5 °C. The corresponding concentrations and incubation periods are shown in the following table:

Test Temperature Sample Concentration (mg/L) Test Duration
25 ± 0.5 °C 0.3195 30 hours
35 ± 0.5 °C 0.3002 8.75 hours
15 ± 0.5 °C 0.3000 98 hours

Duration:

30 h

pH:

4

Temp.:

25

Initial conc. measured:

0.32 mg/L

Duration:

30 h

pH:

7

Temp.:

25

Initial conc. measured:

0.32 mg/L

Duration:

30 h

pH:

9

Temp.:

25

Initial conc. measured:

0.32 mg/L

Duration:

8.75 h

pH:

4

Temp.:

35

Initial conc. measured:

0.3 mg/L

Duration:

8.75 h

pH:

7

Temp.:

35

Initial conc. measured:

0.3 mg/L

Duration:

8.75 h

pH:

9

Temp.:

35

Initial conc. measured:

0.3 mg/L

Duration:

98 h

pH:

4

Temp.:

15

Initial conc. measured:

0.3 mg/L

Duration:

98 h

pH:

7

Temp.:

15

Initial conc. measured:

0.3 mg/L

Duration:

98 h

pH:

9

Temp.:

15

Initial conc. measured:

0.3 mg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

Please see the any other information on methods section for all the calculations and equations used within the study.

Preliminary study:

As the test item had shown to be unstable during the method development stages of this study, the preliminary test (Tier 1) was not performed.

Test performance:

The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines.

Transformation products:

no

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0.066 h-1

DT50:

10.4 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

6.72 h-1

DT50:

10.3 h

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.067 h-1

DT50:

10.4 h

Type:

(pseudo-)first order (= half-life)

Details on results:

Discussion
The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines.

It has been observed that the rate of hydrolysis does not change significantly within the pH range tested, i.e. from pH 4 to pH 9.

The Arrhenius plot was constructed using the data shown in the following tables:

 

Table 1: pH 4 Arrhenius Data

 

T (ºC)	T (K)		kobs(h^-1)	Ln kobs
15	288	3.47 x 10^-3	1.43 x 10^-2	-4.25
25	298	3.35 x 10^-3	6.87 x 10^-2	-2.68
35	308	3.25 x 10^-3	0.269	-1.31

 

From the graph of the above data, the rate constant and half-life at 25 °C have been estimated to be as follows:

 

k_obs      =         6.63 x 10^-2 h^-1

t_½        =         10.4 h

Table 2   pH 7 Arrhenius Data

 

T (ºC)	T (K)		kobs(h^-1)	Ln kobs
15	288	3.47 x 10^-3	1.39 x 10^-2	-4.28
25	298	3.35 x 10^-3	7.04 x 10^-2	-2.65
35	308	3.25 x 10^-3	0.281	-1.27

 

From the graph of the above data, the rate constant and half-life at 25 °C have been estimated to be as follows:

 

k_obs      =         6.72 x 10^-2 h^-1

t_½        =         10.3 h

Table 3    pH 9 Arrhenius Data

 

T (ºC)	T (K)		kobs(h^-1)	Ln kobs
15	288	3.47 x 10^-2	1.29 x 10^-2	-4.35
25	298	3.35 x 10^-2	7.18 x 10^-2	-2.63
35	308	3.25 x 10^-2	0.290	-1.24

 

From the graph of the above data, the rate constant and half-life at 25 °C have been estimated to be as follows:

 

k_obs      =         6.68 x 10^-2 h^-1
t_½        =         10.4 h

Tier 3:

The chromatography of the hydrolysed test solutions from Tier 2, indicated that the degradation product eluted at approximately 3 minutes, since this peak increased as the test item peak decreased due to hydrolysis (see the typical chromatography presented).

 

The MS spectrum at the apex position of the test item peak is presented in Appendix 1. The most significant ions were assigned as shown in the following table.

 

Table 4:

 

Mass/Charge Ratio (m/z)	Possible Assignment
291	Base peak. Corresponds to the gain of NH4. Molecular ion adduct: [CH3(CH2)7N(CH3)2BCl3NH4]^+
238	Corresponds to the loss of Cl. Resulting fragment ion: [CH3(CH2)7N(CH3)2BCl2]^+

 

The most significant ion was assigned as shown in the following table.

 Table 5:

Mass/Charge Ratio (m/z)	Possible Assignment
158	Base peak. Corresponds to the loss of BCl3with gain of H. Resulting fragment ion: [CH3(CH2)7NH(CH3)2]^+

The rate constants and estimated half-lifes at 25 °C of the test item are shown in the following table:

 

Table 6

 

pH	Rate constant (h^-^1)	Estimated half-life at 25 °C (h)
4	6.63 x 10^-2	10.4
7	6.72 x 10^-2	10.3
9	6.68 x 10^-2	10.4

Validity criteria fulfilled:

yes

Conclusions:

Under study conditions, the estimated half-lives of the test substance at 25 °C was found to be 10.4, 10.3 and 10.4 for pH 4,7 and 9 respectively (Harlan, 2015).  

Executive summary:

A study was conducted to evaluate the rate of hydrolysis of the test substance, trichloro(N,N dimethyloctylamine)boron according to the OECD Guideline 111 and EU Method C.7 in compliance with GLP. The study was conducted under dark conditions using three buffer solutions (Potassium hydrogen phthalate) Ph 4, (Disodium hydrogen orthophosphate) (anhydrous) pH 7, Disodium tetraborate Sodium chloride (pH 9). The three sample solutions were prepared in stoppered glass flasks at a nominal concentration of 3.0 x 10E-4 g/L in the corresponding three diluted buffer solutions.  1% v/v acetonitrile was used as co-solvent to aid solubility. The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the estimated water solubility. The test solutions were split into individual vessels for each data point.  The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines. It has been observed that the rate of hydrolysis does not change significantly within the pH range tested, i.e., from pH 4 to pH 9. Under study conditions, the estimated half-lives of the test substance at 25 °C was found to be 10.4, 10.3 and 10.4 for pH 4,7 and 9 respectively (Harlan, 2015).  

Key value for chemical safety assessment

Half-life for hydrolysis:

10.4 h

at the temperature of:

25 °C

Additional information

A study was conducted to evaluate the rate of hydrolysis of the test substance, trichloro(N,N dimethyloctylamine)boron according to the OECD Guideline 111 and EU Method C.7 in compliance with GLP. The study was conducted under dark conditions using three buffer solutions (Potassium hydrogen phthalate) Ph 4, (Disodium hydrogen orthophosphate) (anhydrous) pH 7, Disodium tetraborate Sodium chloride (pH 9). The three sample solutions were prepared in stoppered glass flasks at a nominal concentration of 3.0 x 10E-4 g/L in the corresponding three diluted buffer solutions.  1% v/v acetonitrile was used as co-solvent to aid solubility. The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the estimated water solubility. The test solutions were split into individual vessels for each data point.  The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines. It has been observed that the rate of hydrolysis does not change significantly within the pH range tested, i.e., from pH 4 to pH 9. Under study conditions, the estimated half-lives of the test substance at 25 °C was found to be 10.4, 10.3 and 10.4 for pH 4,7 and 9 respectively (Harlan, 2015).