N,N'-(2-(4-(2-aminobenzamido)butyl)pentane-1,5-diyl)bis(2-aminobenzamide)

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental Phase: 14 June 2020 to 05 September 2020.

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)

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

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 1 Test

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 1 Test

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 1 Test

Duration:

6 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 2 Test

pH:

4

Temp.:

60 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 2 Test

Duration:

3.5 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

0.001 g/L

Remarks:

Tier 2 Test

Number of replicates:

Duplicate samples for each pH.

Preliminary study:

The extent of hydrolysis after 24 and 120 hours at pH 4 at 50 °C indicated that a further test (Tier 2) was required to estimate the rate constant and half-life at 25 °C.

Transformation products:

not measured

Remarks:

As the test item contains three hydrolysable, amide functional groups, the hydrolysis products were considered to be, ultimately, anthranilic acid (2-aminobenzoic acid) (CAS #: 118-92-3) and 4-aminomethyl-1,8-octanediamine (CAS #: 1572-55-0).

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

As the test item contains three hydrolysable, amide functional groups, the hydrolysis products were considered to be, ultimately, anthranilic acid (2-aminobenzoic acid) (CAS #: 118-92-3) and 4-aminomethyl-1,8-octanediamine (CAS #: 1572-55-0).

Key result

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0.042 h-1

DT50:

16.3 h

Type:

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

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Tier 2 Test Results

 

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

 

pH 4 Arrhenius Data (Tier 2 Test)

Temperature (ºC)	Temperature (K)	1/ (T(K))	kobs (hr^-1)	ln kobs
30	303.15	0.0033	0.0556	-2.89
50	323.15	0.0031	0.188	-1.67
60	333.15	0.003	0.267	-1.32

 

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

 

k = 4.24 x 10^-2 hour^-1

t_½= 16.3 hours

Validity criteria fulfilled:

yes

Conclusions:

The estimated half-life at 25 °C of the test item at pH4 is 16.3 hours and >1 year at pH 7 and 9.

Executive summary:

Introduction

The hydrolysis as a function of pH of N,N'-(2-(4-(2-aminobenzamido)butyl)pentane-1,5-diyl)bis(2-aminobenzamide) was determined using a procedure designed to be compatable with the following guidelines:

• Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004
  
  
• Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No. 440/2008 of 30 May 2008

Method

Preparation of the Test Solutions

Stock solutions of test item were prepared at a nominal concentration of 1.0 mg/L in the three buffer solutions; a 1% co-solvent of tetrahydrofuran was used to aid solubility. The stock solutions were split into individual glass vessels, sealed with minimal headspace, for each data point. These sample solutions were shielded from light whilst maintained at the test temperature.

Preliminary Test/Tier 1

Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours.

 

Tier 2 Testing

Results from the Preliminary test/Tier 1 showed it was necessary to undertake further testing at pH 4.

Analysis of the Sample Solutions

Duplicate sample solutions were taken at various time points. The pH of each solution recorded. The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC).

Samples

An aliquot of each sample solution was diluted by a factor of two using tetrahydrofuran.

Standards

Duplicate standard solutions of test item were prepared in tetrahydrofuran: high purity water (50:50 v/v) at a nominal concentration of 0.5 mg/L.

Matrix blanks

Tetrahydrofuran: relevant buffer solution (50:50 v/v) Standard blank Tetrahydrofuran: high purity water (50:50 v/v)

The standard and sample solutions were analysed by HPLC.

Results

The results of the analysis for hydrolysis as a function of pH are given in the following table:

pH	Estimated Rate Constant at 25 °C (hr^-1)	Estimated Half-Life at 25 °C
4	4.24 x 10^-2	16.3 hours
7	-	> 1 year
9	-	> 1 year

Conclusion

The estimated half-life at 25 °C of the test item at pH4 is 16.3 hours and >1 year at pH 7 and 9.

Description of key information

Hydrolysis as function of pH data summary.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The estimated half-life at 25 °C of the test item at pH4 is 16.3 hours and >1 year at pH 7 and 9.