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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 200-822-1 | CAS number: 74-93-1
Phototransformation in air
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
A number of studies have examined the photodegradation of methanethiol. In reaction with OH radicals,the rate constant for reaction of methanethiol with hydroxyl radicals at room temperature was 2.56 x 10-11cm3/(molecule•sec) with 50% degradation after 46 minutes. The atmospheric lifetime was calculated to range from 66 minutes to 35 hours in this study (Lee and Tang, 1983). An estimated half life of 3.8 hours (also based on reaction with OH radicals) and overall hydroxyl rate constant of 3.3 x 10-11cm3/(molecule•sec) was derived from the EPISuite model (U.S. EPA, 2000). In a study measuring photooxidation of methanethiol with alkyl nitrites as the source of OH radicals, the main products of the reaction were SO2, CH3SO3H and H2SO4, with the final yields of 29, 40 and ≥ 2%, respectively. Degradation was 100% after 4 minutes (Hatakeyama and Akimoto, 1983). In a reaction with NOx, the half life of methanethiol was 2 hours with 85% degraded after 5 hours (Sickleset al.,1978).
Sulfur dioxide is oxidized rapidly by both homogeneous and heterogeneous reactions and is removed from the atmosphere by precipitation and by dry deposition on surfaces, mainly as sulfuric acid (ATSDR, 1998). The acidic photo-oxidation products of methanethiol could contribute to the acidification of the aquatic environment.
Upon reaction with OH radicals, the half life of sodium methanethiolate was estimated to be 10 days using the EPISuite model (U.S. EPA, 2000). The estimated overall hydroxyl rate constant was 1.1 x 10-12cm3/(molecule•sec).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.
