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Diss Factsheets
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EC number: 202-443-7 | CAS number: 95-71-6
- 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
Additional information on environmental fate and behaviour
Administrative data
- Endpoint:
- additional information on environmental fate and behaviour
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 19.05.2018 – 13.09.2018
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Justification for type of information:
- study originally performed to examine hydrolysis of the test substance
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 018
- Report date:
- 2018
Materials and methods
Test guideline
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- other: OECD Test No. 111: Hydrolysis as a Function of pH
- Version / remarks:
- 2004
- Deviations:
- yes
- Remarks:
- transformation products were not identified
- GLP compliance:
- no
- Remarks:
- accredited by DAkkS
Test material
- Reference substance name:
- 2-methylhydroquinone
- EC Number:
- 202-443-7
- EC Name:
- 2-methylhydroquinone
- Cas Number:
- 95-71-6
- Molecular formula:
- C7H8O2
- IUPAC Name:
- 2-methylbenzene-1,4-diol
- Test material form:
- solid: particulate/powder
Constituent 1
Results and discussion
Any other information on results incl. tables
Although the test item methylhydroquinone does not possess functional groups being associated with hydrolysis, an abiotic degradation takes place in buffered aqueous test samples, apparently. During the tests a discoloration from colorless to yellowish-brown/dark brown was observed. In the subsequent liquid extraction using ethyl acetate the organic phase took over this yellow-brown discoloration whereas the aqueous phase maintained it and was only weakly discolored in turn. By concentration measurement of methylhydroquinone by means of GC-MS a decrease in concentration in time was determined. However, the GC-MS chromatograms showed no new additional and prominent signals. Hence, it was initially assumed that the degradation products are possibly not extractable using ethyl acetate. The subsequent performed GC-MS measurements of the aqueous phase were not successful. No sufficiently volatile substances could be detected.
ESI-MS analysis revealed for the sample (pH 7-buffer, over 24 h, 50°C) a clearly different mass spectrum in comparison to the one of methylhydroquinone. A multitude of fragment and fragment groups were detected in the m/z-area of 150 – 700. A main component could not be determined by means of spectra comparison. Also, an unambiguous identification of single compounds was not possible. The most obvious assumption for this outcome is a slow reaction or slow reactions with the buffer system. A complex reaction mixture with no identifiable products is the result. On the TLC-plate a grey track below the methylhydroquinone spot was observed.
In NMR-measurements also no conclusions could be drawn to possibly formed main degradation products. A multitude of further signals with low intensity could be observed in the shift range of aliphatic protons (0.5 - 2.5 ppm). Also, additional signals in the shift area of aromatic protons were observed.13C-NMR measurements did not provide further insights.
Applicant's summary and conclusion
- Conclusions:
- Methylhydroquinone is stable in aqueous solution at pH 4 at 20°C, 27°C and 50°C for at least 5 days.
Methylhydroquinone is not stable in aqueous solution at pH 7 and pH 9 at 20°C, 27°C and 50°C and degrades within 700 h to at least 50% of the intial concentration. - Executive summary:
The tests were performed to describe the abiotic degradation of methylhydroquinone considering the scenario of an unintended release into surface water. Test performed at different pH values and temperatures revealed a relative stability of methylhydroquinone at pH 4 and distinct temperature-dependent degradation kinetics at pH 7 and pH 9. For both pH values and all applied incubation temperatures the kinetic parameters k (velocity constant) and DT50 (time to reach 50% of the initial concentration) were calculated. The performed tests to describe the occuring reactions lead to the hypothesis that the observed process is not a hydrolysis of methylhydroquinone but a slow reaction with the used buffer system leading to a complex reaction mixture with substances that could not be identified any further.
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