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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
other: handbook data
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
no guideline followed
Transformation products:
yes
Remarks:
sophorose and deacetyled free acids
Details on hydrolysis and appearance of transformation product(s):
Diacetylated lactonic sophorolipids have both esteric and glycosidic bonds which exhibit different sensitivities to either acid or alkaline hydrolysis. The latter will only hydrolyse the esters whereas acid hydrolysis at first cleaves the esters and, under more harsh reaction conditions, removes the sophorose moiety to yield a hydroxy fatty acid. In performing alkaline hydrolysis, the gradual removal of the esters transforms the solid and insoluble diacetyl lactone into a heavier-than-water and immiscible liquid phase, which in itseld ontains 40 % of water and a mixture of sophorolipids woth a varying degree of acetylation and lactonization. In this process, both the sensitivity of the esteric bonds to an alkaline pH and the pH itself play a role. The esters will hydrolyse above a pH of 7 and subsequently release carboxylic groups, lowering the pH, which decreases the solubility of the sophorolipids. Further hydrolysis decreases the hydrophobicity of the mixture and makes it water soluble in increasingly more acidic environments. Ultimately, only the deacetylated free acid sophorolipid is found, which dissolves at a moderately acidic pH or higher, indicating that at least a fraction of the free carboxylic function must be ionized in order for it to dissolve. Acid hydrolysis occurs more slowly due to the decreased solubility and first results in a similar liquid hydroxy fatty acid after hydrolysing the glycosidic bonds.

Figure 1 shows the ultimate results of both alkaline and acidic hydrolysis.

Validity criteria fulfilled:
not applicable
Conclusions:
The test substance hydrolyses under to both acid and alkaline conditions.
Executive summary:

The test substance has both esteric and glycosidic bonds which exhibit different sensitivities to either acid or alkaline hydrolysis. As ultimate transformation products, sophorose and deacetyled free acids are found.

Description of key information

Testing is not required. According to the REACH Regulation, Annex VIII, column 2 the study does not need to be conducted if the substance is readily biodegradable.

Key value for chemical safety assessment

Additional information

Testing is not required. According to the REACH Regulation, Annex VIII, column 2 the study does not need to be conducted if the substance is readily biodegradable.

Handbook data describe that the test substance hydrolyses under to both acid and alkaline conditions. Transformation products are sophorose and deacetyled free acids.