1,2,3-Propanetriol, mono- and diformates

Hydrolysis

Description of key information

The test item hydrolyses quickly at pH 1.2, 4, 7, and 9 and temperatures ranging between 20 and 60 °C. Hydrolysis products are formic acid and glycerol. 

Key value for chemical safety assessment

Half-life for hydrolysis:

28.6 h

at the temperature of:

20 °C

Additional information

The hydrolysis of the test item 1,2,3-propanetriol, mono- and diformates was determined at the pH values 1.2, 4 and 7 according to OECD test guideline 111. At pH 9, the rate of hydrolysis was too fast for a calculation of kinetic parameters. The lowest pH of 1.2 was included to simulate hydrolysis under physiological conditions (in gastric fluid). The individual results are summarised as follows:

pH 1.2 (37 °C):k_obs[h^-1] = 1.350 ± 0.003;t_0.5[h] = 0.513 ± 0.001

pH 4:

20 °C:k_obs[h^-1] = 0.002 ± 4·10^-6;t_0.5[h] = 374.8 ± 0.7

50 °C:k_obs[h^-1] = 0.018 ± 2·10^-5;t_0.5[h] = 0.041 ± 5·10^-5

60 °C:k_obs[h^-1] = 37.72 ± 0.04;t_0.5[h] = 16.87 ± 0.02

A[h^-1] = 2.3·10⁸

E_A[kJ/mol] = 62.3 ± 0.1

pH 7:

20 °C:k_obs[h^-1] = 0.024 ± 2·10^-5;t_0.5[h] = 28.64 ± 0.03

40 °C:k_obs[h^-1] = 0.182 ± 1·10^-4;t_0.5[h] = 3.817 ± 0.003

50 °C:k_obs[h^-1] = 0.626 ± 0.001;t_0.5[h] = 1.107 ± 0.002

60 °C:k_obs[h^-1] = 1.457 ± 0.003;t_0.5[h] = 0.476 ± 0.001

A[h^-1] = 2.2·10¹³

E_A[kJ/mol] = 84.1 ± 0.3

The parameters for generation of the hydrolysis products could not be calculated. Different methods like HPLC and GC-MS, including derivatisation of the hydrolysis products, were investigated for their quantification, but no suitable method for measurement of degradation products could be developed.

The hydrolysis of the test item leads to generation of formic acid and glycerol. Based on the molecular structures of the test item (ester bonds) this is the only plausible mechanism for hydrolytical degradation.This result is further supported by the read-across partner ethylene diformate (source substance):

Reliable QSAR calculations (HYDROWIN v2.00) resulted in DT50 values of 1.24 d at pH 7 and 2.98 h at pH 8 (Müller, 2011). Thus, the substance will hydrolyse, yielding the expected hydrolysis products ethylene glycol and formic acid upon contact with water. Further analytical investigations in the available ecotoxicological studies performed with ethylene diformate resulted in DT50 values of 4 h in standard algae medium (OECD 201; Vryenhoef, 2013) and 11 h in standard daphnia medium (OECD 202; Vryenhoef, 2012) showing that the substance is susceptible to hydrolysis.