Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Principles of method if other than guideline:
Since the test item was expected to be hydrolytically unstable the preliminary test (Tier 1) described in OECD 111 was omitted.
The study was started with “Hydrolysis of unstable substances (Tier 2)“ according to OECD 111 at pH 4, 7 and 9.
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Test Item(s): Ethanol, 2,2´-oxybis-, reaction products with 3-(triethoxysilyl)-1-propanamine
Chemical Name: Ethanol, 2,2´-oxybis-, reaction products with 3-(triethoxysilyl)-1-propanamine
CAS No.: 152261-43-3
Batch No.: 1190291820
Appearance/Colour: colourless liquid
Expiry Date: 2020-01-29
The identity and purity of the test item is investigated under our LIMS reference 19-04260 (non-GLP).
Specific details on test material used for the study:
Characterization according to Sponsor`s Information:
Test Item(s): Ethanol, 2,2´-oxybis-, reaction products with 3-(triethoxysilyl)-1-propanamine
Chemical Name: Ethanol, 2,2´-oxybis-, reaction products with 3-(triethoxysilyl)-1-propanamine
CAS No.: 152261-43-3
Batch No.: 1190291820
Appearance/Colour: colourless liquid
Expiry Date: 2020-01-29
The identity and purity of the test item is investigated under our LIMS reference 19-04260 (non-GLP).
Radiolabelling:
not specified

Study design

Analytical monitoring:
yes
Details on sampling:
Conduct of the Study
The stability of the test item in aqueous systems is investigated at pH 4, pH 7, and pH 9 at 25°C, 50°C, and 70°C.
About 25 mg of the test item were dissolved in about 2 g D2O and 18 g of the respective buffer solution (pH 4, 7, and 9).
An aliquot of these solution is transferred into an NMR tube and analysed by 1H NMR spectroscopy at the respective temperature. The tubes are kept at the respective temperature in the NMR spectrometer and are measured after the time intervals specified below

Results and discussion

Transformation products:
no
Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.001 s-1
DT50:
578 s
Type:
not specified
Key result
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0.008 s-1
DT50:
88 s
Type:
not specified
Remarks on result:
other: Hydrolysis rate: These values were derived from only two concentration values and have to be regarded as estimates.
Key result
pH:
4
Temp.:
70 °C
Remarks on result:
other: Hydrolysis rate & Half-life:
Remarks:
Too fast to establish
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0 s-1
DT50:
1 733 s
Type:
not specified
Key result
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0.004 s-1
DT50:
178 s
Type:
not specified
Key result
pH:
7
Temp.:
70 °C
Remarks on result:
other: Hydrolysis rate & Half-life:
Remarks:
Too fast to establish
Key result
pH:
9
Temp.:
25 °C
Remarks on result:
other: Hydrolysis rate & Half-life:
Remarks:
Too fast to establish
Key result
pH:
9
Temp.:
50 °C
Remarks on result:
other: Hydrolysis rate & Half-life:
Remarks:
Too fast to establish
Key result
pH:
9
Temp.:
70 °C
Remarks on result:
other: Hydrolysis rate & Half-life:
Remarks:
Too fast to establish
Details on results:
Since the test item was expected to be hydrolytically unstable the preliminary test (Tier 1) described in OECD 111 was omitted.
The study was started with “Hydrolysis of unstable substances (Tier 2)“ according to OECD 111 at pH 4, 7 and 9.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The temperature dependence of the rate constant at pH 4 is given by:
ln k = -7262.8 / T + 17.634
The temperature dependence of the rate constant at pH 7 is given by:
ln k = -8776.3 / T + 21.612
The temperature dependence of the rate constant at pH 9 could not be determined due to fast hydrolysis.
Please note, that the regression curves are based on only two points, because it was not possible to determine the rate of hydrolysis at 70 °C.
Executive summary:

The test item can be described as a mixture of trialkoxy alkyl silanes containing ethanol and diethylene glycol as alcohol parts.

The initially formed trihydroxy alkyl silane undergoes secondary condensation reactions to form oligomeric/polymeric networks under formation of Si-O-Si moieties. This polymeric/oligomeric material could not be identified in the test solutions, due to their low concentrations and the poor NMR sensitivity of the 29Si nucleus.

In an additional experiment, a more concentrated solution of the test item in D2O was prepared and analysed by 29Si NMR spectroscopy. The obtained spectrum can be compared with a spectrum of the non-hydrolysed test item in chloroform-d1.

The 29Si NMR spectrum obtained for the test item in chloroform solution. The signal groups at -45 ppm and -52 ppm can be attributed to the test item, no other silicon species can be detected.

The 29Si NMR spectrum of the aqueous solution of the test item is shown in Figure 8. The observed broad signals at –55 to –70 ppm indicate hydrolysis/condensation under formation of Si-O-Si networks leading to oligomeric/polymeric structures of the test item.