Methyl formate

Phototransformation in air

Description of key information

After evaporation or exposure to air, methyl formate and its hydrolysis product methanol and formic acid will be slowly degraded by photochemical processes.

Additional information

Parent compound (CAS 107-31-3)

Based on an measured OH radical rate constant of 0.227E-12 cm³/(molecule*sec), the half-life of methyl formate in air was calculated to be 70.7 d using the equitation cited in TGD, Part II, pp50 (0.5 E06 OH/cm³, 24-h day) (conditions: sensitiser for indirect photolysis: OH; Atkinson, 1989). Additionally, the half-life of methyl formate in air was calculated with EPI Suite v4.11, using AOPWIN v1.92 and was estimated to be 73.732 d (BASF SE, 2021). The substance was within the applicability domain of the estimation model.

Moreover, according to the available hydrolysis study for the substance, Methyl formates' susceptibility to hydrolysis increases with pH as well as with temperature. The hydrolysis half-life ranges from 410 h at pH 4 and 20 °C to less than 1 hour at pH 9 and 25 °C (OECD 111, BASF SE, 2010). Therefore, it can be concluded, that under environmentally relevant conditions (pH 7-9) the rapid hydrolysis will be the major fate process of the methyl formate due to the short half-life in aqueous solution. Therefore, this estimate may be of low relevance. Thus, the assessment of the environmental fate of the substance is also based on the available experimental data for the hydrolytic products: formic acid and methanol.

 

Hydrolysis product formic acid (CAS 64-18-6):

The phototransformation in air was calculated for the substance with AOPWIN v1.92, implemented in EPISuite v4.11. Based on an estimated OH radical rate constant of 0.52E-12 cm³/molecule-sec, the half-life was calculated to be 30.8 d; for this calculation a 24 -hour day as well as a sensitizer-concentration (OH-radicals) of 0.5E+06 molecules/cm³ were assumed (BASF SE, 2021). The substance is within the applicability domain of the estimation model.

Hydrolysis product methanol (CAS 67-56-1):

Based on a measured OH-radical rate constant of 9.32E-13 cm3/(molecule*sec), the half-life of methanol was calculated to be 17.2 days (conditions: sensitiser for indirect photolysis: OH; Atkinson, 1989; peer-reviewed data OECD, 2004).

 Based on the available measured data the substance will be slowly degraded by photochemical processes, after evaporation or exposure to air.

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of the methyl formate and its hydrolysis product formic acid (Q)SAR results were used for phototransformation in air. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

 

Overall, based on the available experimental and estimated data it can be concluded, that the parent compound methyl formate along with its hydrolysis products formic acid and methanol will be slowly degraded by photochemical processes.