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Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP. In addition, the following acceptable restrictions are identified: No evidence of replicates or checks against well established references, Loading Concentrations may be approximate, and there are no uncertainties quoted, and LOQ is not stated.
Principles of method if other than guideline:
Screening method based on 1H-NMR spectroscopy. The formation of the product methanol was observed.
GLP compliance:
no
Buffers:
pH 4: citrate buffer, pH 7: phosphate buffer and pH 9: borate buffer
Preliminary study:
No preliminary study was carried out.
Transformation products:
yes
No.:
#1
No.:
#2
Details on hydrolysis and appearance of transformation product(s):
The formation of methanol and the formation and decay of the mono-methoxy intermediate were followed during the reaction.
pH:
4
DT50:
< 3 min
Remarks on result:
other: At room temperature
pH:
7
DT50:
15 min
Remarks on result:
other: At room temperature
pH:
9
DT50:
< 3 min
Remarks on result:
other: At room temperature
Other kinetic parameters:
None determined.

The NMR experiment allowed the loss of the first methoxy group to be followed and the formation of the monomethoxy-intermediate, which is eventually also hydrolysed. All methoxy groups are ultimately converted to methanol.

Taking into account only the original test substance and final products, a formal half-life of 15 mins was calculated. This corresponds to the slope of the regression line in the Arrhenius plot. It was noted that the axis intercept for this plot was at ca. 70% rather than being close to 100% at time zero. The authors of the report concluded that this probably resulted from fast hydrolysis of the original silane to the mono-methoxy-intermediate, which then hydrolyses much slower. This behaviour was not investigated in more detail because it was clear that hydrolysis was very rapid.

Conclusions:
Hydrolysis half-lives of <3 min at pH 4, 15 min at pH 7 and <3 min at pH 9 were determined at room temperature in a non-guideline study conducted according to generally accepted scientific principles, but not in compliance with GLP.
Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification for grouping of substances provided in IUCLID Section 13.
Reason / purpose:
read-across source
Transformation products:
yes
No.:
#1
No.:
#2
pH:
4
DT50:
< 3 min
Remarks on result:
other: At room temperature
pH:
7
DT50:
15 min
Remarks on result:
other: At room temperature
pH:
9
DT50:
< 3 min
Remarks on result:
other: At room temperature

Description of key information

Half-Life time <3 min at pH 4 and 9, 15 min at pH 7 (no guideline, no GLP), RL2

Key value for chemical safety assessment

Additional information

There are no hydrolysis data available for N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine (CAS 23410-40-4) therefore good quality data for the analogue substance, N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine (CAS 3069-29-2) have been read across. Both substances hydrolyse rapidly to comparable hydrolysis products, N-[3-(dihydroxymethylsilyl)-2-methylpropyl]ethylenediamine and N-[3-(hydroxydimethylsilyl)propyl]ethylenediamine. It is therefore considered valid to read-across the results for N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine and N-[3-(dimethoxy methylsilyl)propyl]ethylenediamine to fill the data gap for the registered substance.

Hydrolysis half-lives of <3 min at pH 4, 15 min at pH 7 and <3 min at pH 9 were determined at room temperature in a non-guideline study conducted according to generally accepted scientific principles, but not in compliance with GLP (Degussa Goldschmidt AG, 2006).

 The half-life of a substance at pH 2 is calculated based on:

t1/2(pH 2) = t1/2(pH 4) / 100

The calculated half-life of N-[3-(dimethoxymethylsilyl)propyl]ethylenediamine at pH 2 is therefore 5 seconds.