Reaction mass of [3-(trimethoxysilyl) propyl]urea, [3-(dimethoxyethoxysilyl) propyl]urea, [3-(methoxydiethoxysilyl) propyl]urea and [3-(triethoxysilyl) propyl]urea.

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 Oct 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study. The study was conducted according to the appropriate EU Method C.7 guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sample storage conditions before analysis: Immediately after sampling, the samples were cooled to room temperature by running tapwater. Thereafter, each sample was diluted with mobile phase to obtain concentrations within the calibration range.

Buffers:

- pH: 4, 7 and 9
- Type and final molarity of buffer: sterile 0.05 M acetate (pH 4), phosphate (pH 7) and borate (pH 9)
- Composition of buffer: pH 4: sodium acetate/acetic acid/Milli-Q water; pH 7: potassium dihydrogen phosphate/sodium; pH 9: boric acid/potassium chloride/sodium hydroxide/Milli-Q water

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks: Vessels, glass and 50 mL
- Sterilisation method: filter-sterilized through a 0.2 µm membrane filter and transferred into sterile glass vessels
- Lighting: darkness
- Measures to exclude oxygen: To exclude oxygen, nitrogen gas was bubbled through the solution for approximately 5 minutes
- Details of traps for volatile, if any: The vessels were sealed with a septum-crimpcap

TEST MEDIUM
- Volume used/treatment 50 mL
- Kind and purity of water: Tap water purified by reversed osmosis and subsequently passed over activated carbon and ion-exchange cartridges
- Preparation of test medium: 500 µL of stock solution of A-1160 (methanol stripped) in acetonitrile was added to the sterile buffer solution, resulting in a test substance concentration of 134 mg/L. After preparation, the test solutions at pH 4, pH 7 and pH 9 were placed in a thermostatically controlled waterbath at 50.0 ± 0.5 °C in the dark.

Duration:

2.4 h

Initial conc. measured:

>= 109 - <= 119 mg/L

Duration:

2.4 h

Initial conc. measured:

>= 43.9 - <= 84.5 mg/L

Duration:

2.4 h

pH:

9

Initial conc. measured:

>= 16.8 - <= 81.6 mg/L

Number of replicates:

Two replicates per pH sample.

Positive controls:

not specified

Negative controls:

not specified

Preliminary study:

In the preliminary study, the half-life time was found to be under aqueous solutions buffered at 25 °C < 1 day at pH 4, pH 7 and pH 9. For component M2 at pH 7, a decrease in concentration of 46% was observed. A second test at pH 7 was comparable with the first results (i.e. 44%).

Transformation products:

not measured

pH:

4

Temp.:

25 °C

DT50:

< 12 h

pH:

7

Temp.:

25 °C

DT50:

< 12 h

pH:

9

Temp.:

25 °C

DT50:

< 12 h

The concentration of A·1160 (methanol slripped) was determined using an LC·MS·MS

analytical method. Quantitative analysis ware based on the three major components (Notox

identification M2, M3 end M4) in A·1160 (methanol stripped).

 

M2: H₂N-(C=O)-NH-(CH2)₃Si(OCH₂CH₃)₂(OCH₃)

M3: H₂N-(C=O)-NH-(CH2)₃Si(OCH₂CH₃) (OCH₃)₂

M4: H₂N-(C=O)-NH-(CH2)₃SI(OCH₃)₃

Table 1: Results of the hydrolysis of A-1160 (methanol stripped) at 50 ± 05 °C
pH Code	Measured pH value	Component	Concentration test substance (mg/L)^1after
			0 hours	2.4 hours		5 days
4	4.00^2/ 4.00^3	M2	119	0	(0%)^4	-^5
		M3	114	0	(0%)^4	-^5
		M4	109	0	(0%)^4	-^5
7	7.03^2/ 7.01^3	M2	84.5	45.4	(54%)^4	-^5
		M3	69.8	12.7	(18%)^4	-^5
		M4	43.9	0	(0%)^4	-^5
7	7.06^2/ 7.04^3	M2	164^7	92.5^6,7	(56%)^4	-^5
		M3	165^7	34.2	(21%)^4	-^5
		M4	157^7	1.8^6	(1%)^4	-^5
9	8.97^2/ 8.98^3	M2	81.6	0	(0%)^4	-^5
		M3	52.0	0	(0%)^4	-^5
		M4	16.8	0	(0%)^4	-^5

¹mean value of duplicate injections. The maximum deviation between the response was < 10%

²At t = 0 hours.

³At t = 2.4 hours.

⁴Relative concentration.

⁵Not analysed.

⁶Maximum deviation between the response was 14.5% for M2 and 13.0% for M4.

⁷Extrapolated from regression line

Conclusions:

Based on these results, it was concluded that A-1160 (methanol stripped) is hydrolytically unstable in aqueous solutions buffered at pH 4, pH 7 and pH 9.

Description of key information

Half-life at pH 4, 7 and 9 was < 12 h (EU Method C.7), RL1

Additional information

The determination of the hydrolysis rate of Ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (116912-64-2) as a function of pH was based on EU Method C.7 and GLP (NOTOX, 2000a). The concentration of test item was determined using an LC-MS-MS analytival method. Quantitative analysis were based on the three main components M2: H₂N-(C=O)-NH-(CH₂)₃ -Si(OCH₂CH₃)₂(OCH₃); M3: H₂N-(C=O)-NH-(CH₂)₃-Si(OCH₂CH₃)(OCH₃)₂; M4: H₂N-(C=O)-NH-(CH₂)₃-Si(OCH₂CH₃)₃. At pH 4 and pH 9, a decrease in concentration > 50% was observed after 2.4 hours for each component (half-life time at 25 °C < 1day). At pH 7 a decrease in concentration > 50% was observed after 2.4 hours for components M3 and M4 (half-life time at 25 °C < 1 day). For component M2 at pH 7, a decrease in concentration of 46% was observed. To confirm this result, a second test at pH 7 was performed. The decrease in concentration of component M2 was comparable with the first test results (i.e. 44%).

Based on these results, it was concluded that Ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (116912-64-2) is hydrolytically unstable in aqueous solutions buffered at pH 4, pH 7 and pH 9.