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Diss Factsheets
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EC number: 231-472-8 | CAS number: 7575-23-7
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
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Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 02 October - 17 December 2007
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP guideline study
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 111 (Hydrolysis as a Function of pH)
- Principles of method if other than guideline:
- The assessment of the hydrolytic stability of the test item was not possible using Method C7 of Commission Directive 92/69/EEC and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004, due to its susceptibility to oxidation. Based on these guidelines several alternative approaches were performed in order to determine hydrolysis as a function of pH.
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- The Department of Health of the Government of the United Kingdom
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- Sample solutions were taken from the waterbath at various times and the pH of each solution recorded.
- Buffers:
- For composition of buffers see "any other information on materials and methods".
Buffer solutions were vacuum filtered through a 0.2 µm membrane filter to ensure they were sterile and degassed before commencement of the test. The buffer solutions were then subjected to ultrasonication for 15 minutes and sparging with nitrogen for 5 minutes to further minimise dissolved oxygen content. - Transformation products:
- not measured
- pH:
- 9
- Temp.:
- 25 °C
- DT50:
- 1.09 h
- Type:
- (pseudo-)first order (= half-life)
- pH:
- 9
- Temp.:
- 20 °C
- DT50:
- 5.99 h
- pH:
- 9
- Temp.:
- 30 °C
- DT50:
- 3.77 h
- Validity criteria fulfilled:
- not applicable
- Conclusions:
- The assessment of the hydrolytic stability of the test item was not possible using EU Method C.7 and OECD 111, due to its susceptibility to oxidation, irrespective of significant steps taken to eliminate dissolved oxygen from the sample solutions. Besides measures taken to eliminate oxygen from solutions also modification of the test material to exclude functional groups known to be susceptible to oxidation was considered. However, all alternatives were concluded not to achieve desired results.
In conclusion, hydrolysis alone could not be confidently isolated from the remaining influence of oxidation and no half-life data exclusively resulting from hydrolysis could be quantified. Therefore, although ranges for the overall stability of the test item in the aquatic environment at different pH values could be delivered by this hydrolysis study, it is critical to note that oxidation and not hydrlysis may be the primary route of degradation/transformation in the environment.
Reference
It was concluded from testing performed as a whole that no definitive quantification of the hydrolysis characteristics of the test material could be determined using EU Method C.7 and OECD 111, due to experimental variance attributed to the susceptibility of the test material to oxidation.
The test material contains sulphide functional groups which are known to be susceptible to oxidation, typically resulting in disulfide formation. However, critically the test material also contained a number of ester functional groups known to be susceptible to base catalysed hydrolysis, and thus every effort was made to quantify the rate of hydrolysis of these groups. Testing was significantly hampered by the low aqueous solubility of the test material as typically oxidation of a substance becomes more significant at lower concentrations due to any residual dissolved oxygen then being present in excess.
Although hydrolysis was predicted at pH 9 and experimental evidence supported an accelerated rate in the reduction of the test material concentration in solution at this pH, reduction due to hydrolysis alone could not be confidently isolated from the remaining influence of oxidation. Thus, it is critical to note that oxidation and not hydrolysis may be the primary route of degradation/transformation in the environment.
This conclusion has to be drawn from the practical laboratory work irrespective of the significant steps undertaken to eliminate dissolved oxygen from the sample solutions which included:
- degassing of buffer solution by vacuum filtration, ultrasonication and purging with nitrogen gas before use
- use of nitrogen headspace in each sample vessel during incubation
- use of individual test vessels for each time point, which eliminates exposure of the sample solution to air, and therefore to oxygen, when compared to sampling from a single vessel.
In order to ensure stability of the test material during analysis, a solid phase extraction technique was employed (pre-concentration of sample solutions and a matrix transfer to acetonitrile) prior to analysis. Additionally the anti-oxidant BHT was added to the organic solvent used to elute the SPE cartridges and prepare the standard solutions.
No additional information could be gained on the potential oxidation and / or hydrolysis products of the test material.
At pH 4, where hydrolysis would be expected to be neglible, a second order correlation, typical of oxidation was dominant. At pH 7, where the rate of hydrolysis would increase, neglible correlation was obtained. This was concluded to be due to neither the oxidation or hydrolysis pathway being significantly more dominant than the other. At pH 9, the dominat degradation pathway would be anticipated to be hydrolysis, and this was evident from the increased rate in the reduction of the test material concentration in solution and the first order correlation data generated for the preliminary test at least.
As the difficulty of the present hydrolysis study could be clearly identified to be the high susceptibility of the test material towards oxidation, a structural modification of the test substance was considered as a possible solution for testing. However, for several reasons all of the theoretical modification possibilities had to be considered as inappropriate.
Description of key information
It was concluded from the testing performed as a whole that no definitive quantification of the hydrolysis characteristics of the test material could be determined using EU Method C.7 and OECD Method 111, due to experimental variance attributed to the susceptibility of the test material to oxidation (elimination of test substance).
Key value for chemical safety assessment
Additional information
The test material contains sulphide functional groups which are known to be susceptible to oxidation, typically resulting in disulfide formation. However, critically the test material also contained a number of ester functional groups known to be susceptible to base catalysed hydrolysis, and thus every effort was made to quantify the rate of hydrolysis of these groups. Testing was significantly hampered by the low aqueous solubility of the test material as typically oxidation of a substance becomes more significant at lower concentrations due to any residual dissolved oxygen then being present in excess.
Although hydrolysis was predicted at pH 9 and experimental evidence supported an accelerated rate in the reduction of the test material concentration in solution at this pH, reduction due to hydrolysis alone could not be confidently isolated from the remaining influence of oxidation. Thus, it is critical to note that oxidation and not hydrolysis may be the primary route of degradation/transformation in the environment.
This conclusion has to be drawn from the practical laboratory work irrespective of the significant steps undertaken to eliminate dissolved oxygen from the sample solutions which included: (a) degassing of buffer solution by vacuum filtration, ultrasonication and purging with nitrogen gas before use, (b) use of nitrogen headspace in each sample vessel during incubation, and (c) use of individual test vessels for each time point, which eliminates exposure of the sample solution to air, and therefore to oxygen, when compared to sampling from a single vessel.
In order to ensure stability of the test material during analysis, a solid phase extraction technique was employed (pre-concentration of sample solutions and a matrix transfer to acetonitrile) prior to analysis. Additionally the anti-oxidant BHT was added to the organic solvent used to elute the SPE cartridges and prepare the standard solutions.
No additional information could be gained on the potential oxidation and / or hydrolysis products of the test material.
At pH 4, where hydrolysis would be expected to be neglible, a second order correlation, typical of oxidation was dominant. At pH 7, where the rate of hydrolysis would increase, neglible correlation was obtained. This was concluded to be due to neither the oxidation or hydrolysis pathway being significantly more dominant than the other. At pH 9, the dominat degradation pathway would be anticipated to be hydrolysis, and this was evident from the increased rate in the reduction of the test material concentration in solution and the first order correlation data generated for the preliminary test at least.
As the difficulty of the present hydrolysis study could be clearly identified to be the high susceptibility of the test material towards oxidation, a structural modification of the test substance was considered as a further possible solution for testing. However, for several reasons all of the theoretical modification possibilities had to be considered as inappropriate.
The test substance undergoes fast oxidation reducing test substance concentration during hydrolysis test. The resulting experimental difficulties prevent the determination of hydrolysis half-life.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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