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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.

Diss Factsheets

Categories

Categories

Category name:
Methylates

Justifications and discussions

Category definition:
Methanolates
Category rationale:
Cited from OECD, 2006:

The production and use pattern of sodium and potassium methanolates are comparable. The two chemicals have very similar physical and chemical properties. In contact with water they react very fast, quantitative and exothermic to methanol and the corresponding alkali hydroxides (Leal and de Matos, 1991).

X+ -O-CH3 + H2O CH3OH + OH- + X+ (with X= Na+ or K+)

One mol of sodium or potassium methanolate (54.02 g or 70.13 g) yields one mol of methanol (32.04 g) and sodium- or potassium hydroxide (40 g or 56.11 g) respectively.

Due to the very high pKa-value of methanol of 15.5 (Friedrich, Sonnefeld, and Jansen, 1998), the equilibrium is on the side of the reaction products. Toxicological and ecotoxicological studies of methanol and sodium and potassium hydroxide are therefore relevant for these products as well.

The main toxicological characteristic is the corrosivity to skin and mucous membranes that warrants strict exposure controls. The corrosivity also determines the maximum tolerable dose in any animal experiment. The maximum applicable dose level of methanol derived from the methanolates will therefore be considerably lower in experiments with methanolates than in experiments with methanol itself.

In the environment, both effects through pH-changes by the hydroxides, and effects of methanol need to be considered.

Methanol exhibits potential hazardous properties for human health (neurological effects, CNS depression, ocular effects, reproductive and developmental effects, and other organ toxicity). The effects of methanol on the CNS and retina in humans only occur at doses at which formate accumulates due to a rate-limiting conversion to carbon dioxide. In primates, formate accumulation was observed at methanol doses greater than 500 mg/kg bw (which would require a sodium methanolate dose of more than 840 mg/kg bw and a potassium methanolate dose of greater than 1000 mg/kg bw). Repeated exposure to such high dose levels, of methanolates, that are already in the acutely toxic range is highly unlikely due to their corrosive properties. The only exposure situation for sodium and potassium methanolate that could perhaps lead to methanol and formate blood levels resulting in acute neurophysiological and visual disturbances would be accidental dermal exposure to corrosive concentrations that could lead at the same time to an uptake of toxic amounts of methanol through the skin.