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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 241-922-5 | CAS number: 18015-76-4
Endpoint summary
Administrative data
Description of key information
Malachite Green Oxalate (MGO), hydrolysis t1/2 (45%) ca. 145h, dark conditions, ambient temperature
MG, t1/2, phototransformation in water, natural solar = 30h (8h irradiation/day); total phototransformation, 210h, 25°C
Additional information
Malachite Green (MG) does degrade due to hydrolysis with a measured approximate initial half-life of 145 hours at 25°C (45 % decrease in 145 hours, Perez et al, 2007).
The hydrolysis reaction was fit by first-order kinetics model and its apparent rate constant kh was 0.0192/h (R2 = 0.9409). Based on the structure of MG, the triarylmethyl cation is expected to be stabilized by the conjugation that delocalizes the positive charge and a good leaving group. Therefore, the hydrolysis mechanism should be SN1 mechanism and the reaction rate is unrelated to the concentration of the nucleophile H2O. The pH varied from 8.98 to 7.87 in the reaction process. Results from LC–MS conformed to the fact that MG, MG leucocarbinol and Leucomalachite Green can transform naturally to each other in water matrix (Yong et al, 2015).
Photolysis experiments (Perez et al, 2007) showed that total photolytic transformation of MG in the closed batch system occurred after 210 hours at a temperature of 25 °C. During this photolytic transformation of MG, it has been shown that a large number of transformation products were generated.
It has to be taken into account that the photolytic process is expected to be temperature- as well as wavelength-dependent and that the degradation rate can be differently impacted under sunlit natural waters with season (temperature) and depth (light intensity). It is expected that the photolysis rates decrease exponentially with depth and therefore the substance/degradation products distribution in a well-mixed waterbody would be mainly determined by the photolysis in the upper layer. The photodegradation importance in water strongly depends on the light shadow of the water constituents. It has to be taken into account that also the presence of suspended solids or sediments in natural waters may impact on the photoreactivity of the test substance reducing the availability of light; in suspensions containing large amounts of particles the presence of particles may lead to a shift in the photostationary state of the substance.
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.
