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EC number: 202-773-1 | CAS number: 99-62-7
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
In this justification, the read-across (bridging) concept is applied. Please refer to a full version of Read-across statement attached in the section 13 "Assessment reports".
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The underlying hypothesis for the read-across is that the target and the source substance have similar toxicological properties (including the same target organs) due to their structural similarity, resemblance to their chemical reactivity, and therefore a similar mode of action.
The source substance 1,4-diisopropylbenzene is a structural isomer of the target substance 1,3- diisopropylbenzene. The only difference between the target and this source substance is the position of the two isopropyl groups. While for 1,4-diisopropylbenzene both isopropyl groups are in para position at the benzene ring for 1,3-diisopropylbenzene they are in meta position.
The justification is based on similarity of chemical structure, physical-chemical properties and toxicokinetic behavior. As a conclusion, it is scientifically justified to address the endpoint Hydrolysis with data on this substance.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
source substance: 1,4-diisopropylbenzene (or p-DIPB)
structural formula: C12H18
Smiles: CC(C)c1ccc(cc1)C(C)C
Molecular weight: 162 g/mol
CAS 100-18-5
EC No 202-826-9
purity: not specified
target substance: 1.3-diisopropylbenzene (or m-DIPB)
structural formula: C12H18
Smiles: CC(C)c1cccc(c1)C(C)C
Molecular weight: 162 g/mol
CAS 99-62-7
EC No 202-773-1
purity: not specified
No additional information is available on purity of the source and the target substances. Both substances are normally of high purity, containing only minor amounts of impurities that do not influence the read-across validity.
3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports".
4. DATA MATRIX
Please refer to the full version of the read-across statement attached in the section 13 "Assessment reports". - Reason / purpose for cross-reference:
- read-across source
- Transformation products:
- no
- % Recovery:
- >= 105 - <= 110
- St. dev.:
- 3.535
- pH:
- 4
- Temp.:
- 50 °C
- Duration:
- 72 h
- % Recovery:
- >= 81 - <= 96
- St. dev.:
- 10.748
- pH:
- 4
- Temp.:
- 50 °C
- Duration:
- 120 h
- % Recovery:
- >= 105 - <= 106
- St. dev.:
- 0.707
- pH:
- 7
- Temp.:
- 50 °C
- Duration:
- 72 h
- % Recovery:
- >= 100 - <= 107
- St. dev.:
- 4.95
- pH:
- 7
- Temp.:
- 50 °C
- Duration:
- 120 h
- % Recovery:
- >= 110 - <= 123
- St. dev.:
- 9.192
- pH:
- 9
- Temp.:
- 50 °C
- Duration:
- 72 h
- % Recovery:
- >= 86.1 - <= 118
- St. dev.:
- 22.557
- pH:
- 9
- Temp.:
- 50 °C
- Duration:
- 120 h
- Temp.:
- 25 °C
- DT50:
- > 1 yr
- Validity criteria fulfilled:
- yes
- Conclusions:
- The estimated half-life at 25 °C of the test item at pH 4, pH 7 and pH 9 was shown to be greater than 1 year.
- Executive summary:
The estimated half-life at 25 °C of the test item at pH 4, pH 7 and pH 9 was shown to be greater than 1 year. Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.
Reference
Validation
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0.5 to 20 mg/L. This was satisfactory with a correlation coefficient (r2) of 1.000 being obtained. Recovery of analysis of the sample procedure was assessed and proved adequate for the test. At a nominal concentration of 2 mg/L, a mean percentage recovery of 79.4 % was obtained (range 77.4 to 80.3%). Concentrations have not been corrected for recovery of analysis.
Discussion
No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions. An initial attempt at the test had shown that a very small amount of the test item remained after 72 hours for all three pH's. From the chemical structure and physical parameters it was considered that the reduction in test item concentration was not due to hydrolysis but volatilisation. The test item, being a hydrocarbon, had no hydrolysable groups. The test was repeated with a higher percentage of co-solvent to help retain the test item in solution and with no headspace in the sealed sample vessels to minimalise the loss by volatilisation. Although after 120 hours samples pH 4A and pH 9B had reduced by more than 10 % compared to their averaged initial samples, it was considered that this was due to volatilisation as the sample vessels were later found to have a cracked base. It can even be seen with all samples that they were significantly lower than their "as weighed in concentration" and was also seen in the first attempt at the test. Overall, it was considered that the test item did not hydrolyse and had an estimated half-life of greater than 1 year at 25 °C for pH 4, pH 7 and pH 9.
Description of key information
Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.
The estimated half-life at 25 °C of the test item at pH 4, pH 7 and pH 9 was shown to be greater than 1 year.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 1 yr
- at the temperature of:
- 25 °C
Additional information
Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.
The estimated half-life at 25 °C of the test item at pH 4, pH 7 and pH 9 was shown to be greater than 1 year.
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