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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

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Description of key information

According to structural properties, hydrolysis is not expected. Available data demonstrates that hydrolysis at pH ≤8 does practically not occur (WoE for Hydrolysis, 2018).

Moreover, in accordance with column 2 of REACH Annex VIII, the hydrolysis test does not need to be conducted as the substance is readily biodegradable.

Key value for chemical safety assessment

Additional information

The prescribed pH values for the hydrolysis test are pH 4.0, 7.0 and 9.0. At these pH values, dialdehydes such as glyoxal are stable against hydrolysis. Therefore, testing is not necessary.

Dialdehydes, especially glyoxal and methylglyoxal, were intensively examined regarding their hydrolysis behaviour already in the years 1920 - 1930.

It was observed that glyoxal is stable against hydrolysis at pH values < 7.5 (Aryama, 1928; Friedemann, 1927; Sakuma, 1931). In aqueous glyoxal solutions, stable oligomeric or polymeric glyoxal species are in equilibrium with monomeric glyoxal (Shaffer & Friedemann, 1924; Whipple, 1970). With increasing alkalinity glycolic acid is formed, which becomes first detectable at pH 11, and is rapidly formed at pH 12. This alkali influence is interpreted as the shift of the equilibrium between polyglyoxal and monoglyoxal and the increasing tendency towards enolization with increasing pH value (Shaffer & Friedemann, 1924). The mechanism of the internal disproportionation of glyoxal to glycolic acid at high pH values was investigated in D2O (Fredenhagen & Bonhoeffer, 1938). It was found that also at the internal Cannizzaro reaction the hydrogen is transferred directly from one carbon to the other. Glyoxal does not exchange with slightly alkaline D2O, since a possible exchange (i.e. hydrolysis) should be manifested in a deuterium content of the glycolic acid. Thus, the above data demonstrated that hydrolysis at pH ≤8 does practically not occur.

According to structural properties, hydrolysis is not expected.