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Environmental fate & pathways

Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Data referenced in a standard handbook.
Principles of method if other than guideline:
The method is not described.
GLP compliance:
not specified
Preliminary study:
No data are available on the performance of a preliminary study.
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
Details on hydrolysis and appearance of transformation product(s):
Melamine is hydrolyzed by mineral acid or inorganic alkali. Hydrolysis proceeds stepwise, with loss of one, two, or all three amino groups, i.e. producing ammeline, ammelide and cyanuric acid. The product spectrum varies with temperature, pH, and concentration; the end product is cyanuric acid [108-80-5].
Remarks on result:
other: not available
Executive summary:

Melamine is hydrolyzed by mineral acid or inorganic alkali. Hydrolysis proceeds stepwise, with loss of one, two, or all three amino groups, i.e. producing ammeline, ammelide and cyanuric acid.

Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Please refer to the analogue justification attached to section 13
Reason / purpose:
read-across source
Transformation products:
not measured
Remarks on result:
other: Melamine is hydrolyzed by mineral acid or inorganic alkali. Hydrolysis proceeds stepwise, with loss of one, two, or all three amino groups, i.e. producing ammeline, ammelide and cyanuric acid.

Description of key information

Key value for chemical safety assessment

Additional information

Experimental data on the hydrolysis of diphosphoric acid, compound with 1,3,5-triamine (1:2) are not available. The substance is not stable in aqueous environments. It will dissociate forming melamine and pyrophosphate ions at environmentally relevant conditions. Therefore the hydrolysis of the substance components is contemplated separately and is in part based on read across data available for the source substance melamine (CAS 108-78-7). The read across approach is in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. Further justification is given in the analogue justification in IUCLID section 13.

The melamine ion is stable to hydrolysis by water since it does not contain any hydrolysable groups. Available read across data indicate a hydrolisation by mineral acid or inorganic alkali (Ullmann, 2006).

The pyrophosphate ion undergoes further hydrolysis and is converted into orthophosphate ions. Thus the hydrolysis reaction leads directly to the formation of orthophosphate. The kinetics of hydrolysis of triphosphate and pyrophosphate were also studied in sterile lake water and sterile algal culture media and in non-sterile media at 25 °C by Clesceri and Lee (1965a, 1965b),and compared to published results obtained in distilled water. The results showed that triphosphate and pyrophosphate were hydrolysed to orthophosphate in a period of several days. Addition of glucose increased the rate of hydrolysis, indicating that microbial activity was one of the primary mechanisms of hydrolysis.

References:

Clesceri N.L. and Lee G.F. (1965a): Hydrolysis of Condensed Phosphates – II : Sterile Environment, Int. J. Air Wat. Poll. 9, 743-751.

Clesceri N.L. and Lee G.F. (1965b): Hydrolysis of Condensed Phosphates – I : Non-Sterile Environment, Int. J. Air Wat. Poll. 9, 723-742.