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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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Link to relevant study record(s)

Description of key information

Ward et. al (2003), determined that HQEE is hydrolytically stable with t1/2 = > 1 year. 

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
50 °C

Additional information

A reliable measured biodegradation study for HQEE is available and included in the dossier.


Ward et al. (2003) conducted a hydrolysis study in accordance with the OECD 111 method and in compliance with the GLP standards. Hydrolysis of HQEE at 28 mg/L was studied in the dark at 50ºC in sterile aqueous buffered solutions at pH 4 (sodium acetate), pH 7 (phosphate buffer) and pH 9 (sodium borate buffer) for 5 days.   Samples were analysed at 0, 0.5, 1, 1.5, 3.25, 3.75, 24, 48, 72, 96, and 120 hours. At test termination after 5 days, the recovery of HQEE was 99% of the initial at pH 4, 104% of the initial at pH 7, and 104% of the initial at pH 9.  HQEE is considered to be hydrolytically stable (t1/2, > 1 year) based on the recovery of >90% of the HQEE from five day old samples prepared at a concentration less than the approximate half-saturation concentration in water that had been buffered to pH 4,7, and 9.


A reliable (Klimisch 1) hydrolysis study has been conducted for HQEE and is included in this dossier. The key study, Ward et. al (2003), determined that HQEE is hydrolytically stable with t1/2 = > 1 year.  Consequently this study will be taken for the hydrolysis endpoint.