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EC number: 203-317-4 | CAS number: 105-64-6
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
The hydrolysis of di-iso-propyl peroxydicarbonate occurs rapidly. Indeed, the half-life of this peroxide has been determined to be 3.49 hours at pH 4, 3.19 hours at pH 7 and 0.450 hours at pH 9 at 25°C (OECD 111).
Information on similar substances is also available.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 3.19 h
- at the temperature of:
- 25 °C
Additional information
The hydrolysis as a function of pH has been determined for diisopropyl peroxydicarbonate (CAS# 105 -64 -6). Assessment of hydrolytic stability was carried out according to the OECD 111 guideline and GLP requirements (Fox, 2018).
The results are as follows:
pH | Rate constant (h-1) | Estimated half-life at 25 °C (h) |
4 | 0.199 | 3.49 |
7 | 0.217 | 3.19 |
9 | 1.54 | 0.450 |
Under the physiologically relevant conditions of pH 1.2, 37 °C, the half-life of the test item was determined to be 1.31 hours.
Based on the chemical structure of the test item and knowledge of the functional groups present, it was considered that the hydrolysis product was isopropanol (propan-2 -ol) of which two moles would be released for every mole of test item. However, this test only measured the hydrolytic rate for the release of the first iso-propanol product. The remaining di-acid hydrolysis product would breakdown further in to carbon dioxide and water.
Nevertheless, the identification of iso-propanol as hydrolysis product has not been possible during this experiment. Indeed, stock solutions of test item were prepared in acetonitrile to ensure stability and to aid solubility. The acetonitile peak masked the confirmation peak in the degraded sample and thus it has not been possible to confirm the presence of iso-propanol.
Analogue substances to di-iso-propyl peroxydicarbonate showed also a quick hydrolysis. Moreover, the hydrolysis studies done with these other peroxides confirm the hypothesis about the hydrolysis product.
Hydrolytical activity of bis-(2 -ethylhexyl) peroxydicarbonate was determined at pH 4 and 7 according to OECD 111 guideline and GLP requirements (Laus, 2012). Experimental investigations at pH 9 were not feasible due to insufficient accuracy of the analytical method (possible reaction between the target molecule and borate). In the course of the hydrolysis experiment, the following reaction products were detected:
2-ethylhexanoic acid (CAS No. 149-57-5) amounting to maximally 3.2 %, 2-ethyl-1-hexanol (CAS No. 104-76-7, main transformation product amounting to approximately 96 %), 2-heptanone (CAS No. 110-43-0) amounting to maximally 3.9 %, and 3-heptanol (CAS No. 589-82-2) amouting to maximally 1.4 %. Only the main degradation product 2-ethyl-1-hexanol was quantified against an external standard. However, determination of the relative amounts of the minor products is considered to be reliable due to the properties of the FID detector used.
Hydrolysis of bis-(2-ethylhexyl) peroxydicarbonate takes place instantly. From the data it can be concluded that bis-(2-ethylhexyl) peroxydicarbonateis moderately soluble (100-1000 mg/L, 24 h) but hydrolysis takes place rapidly and the intact peroxide is not detectable in aqueous solutions after 24 hours reaction time. The hydrolytical half-life (DT50) ofbis-(2-ethylhexyl) peroxydicarbonate is less than 1 hour at 5 °C.
The hydrolysis as a function of pH has also been determined for di-sec-butyl peroxydicarbonate (CAS# 19910 -65 -7), as a function of pH (Harlan, 2013). Assessment of hydrolytic stability was carried out according to the OECD 111 guideline and GLP requirements.
The results were as follows:
| pH | 15.0± 0.5°C | 25.0± 0.5°C | 37.0± 0.5°C | |||
| Rate constant (s-1) | Half-life | Rate constant (s-1) | Half-life | Rate constant (s-1) | Half-life | |
| 1.2 | - | - | - | 1.40 x 10-4 | 83 mins | |
| 4 | 3.10 x 10-5 | 6.22 hrs | 9.38 x 10-5 | 2.05 hrs | 2.12 x 10-4 | 54 mins |
| 7 | 2.30 x 10-5 | 8.37 hrs | 5.03 x 10-5 | 3.83 hrs | 1.23 x 10-4 | 94 mins |
| 9 | 1.15 x 10-4 | 100 mins | 3.54 x 10-4 | 33 mins | 1.67 x 10-3 | 7 mins |
On generation of an Arrhenius plot for each pH were 3 individual temperatures have been employed, a further estimation of the rate constant and estimated half-life at 25°C of the test item can be obtained from the data set as a whole. This further data evaluation resulted in values as shown in the following table:
| pH | Rate constant (s-1) | Estimated half-life at 25°C |
| 4 | 8.22 x 10-5 | 2.34 hrs |
| 7 | 5.06 x 10-5 | 3.80 hrs |
| 9 | 3.89 x 10-4 | 30 mins |
The test item has been positively identified to hydrolyze to sec-butanol by both acidic and basic mechanisms, with a mass balance/conversion factor of 2 moles of sec-butanol (actual experimental range 1.97 to 1.99) per mol of initial parent test item.
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