Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 201-944-8 | CAS number: 89-83-8
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Reason / purpose for cross-reference:
- reference to other study
- Principles of method if other than guideline:
- Measurements of pH changes during titrations using glass electrodes
- GLP compliance:
- not specified
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 10.62
- Temp.:
- 20 °C
- Conclusions:
- The dissociation constant (pKa) of thymol is 10.62 at 20°C. Therfore thymol is mainly present as undissoicated form under environmentally relevant pH (5 -9)
- Executive summary:
In "IUPAC chemical data series, no. 23" Serjeant & Dempsey published in 1979 with "International Union of Pure and Applied Chemistry, Analytical Chemistry Division Commission on Equilibrium Data" ionisation constants of organic acids in aqueous solution.
The dissociation constant (pKa) of thymol is 10.62 at 20°C. Therefore, thymol is mainly present as undissociated form under environmentally relevant pH (5 -9).
Reference
Description of key information
In "IUPAC chemical data series, no. 23" Serjeant & Dempsey published in 1979 with "International Union of Pure and Applied Chemistry, Analytical Chemistry Division Commission on Equilibrium Data" ionisation constants of organic acids in aqueous solution.
The dissociation constant (pKa) of thymol is 10.62 at 20°C. Therfore thymol is mainly present as undissociated form under environmentally relevant pH (5 -9).
Key value for chemical safety assessment
- pKa at 20°C:
- 10.62
Additional information
The above mentioned value is also listed in the Beilstein database (supporting study) which serves as proof for its reliability.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
