Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 202-905-8 | CAS number: 100-97-0
- 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
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1980
- Reliability:
- 2 (reliable with restrictions)
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Public available literature. No guideline indicated, but to some extent comparable to OECD 111. For details on method see IUCLID5 materials and methods section.
- GLP compliance:
- not specified
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- At suitable time intervals, one culture tube was removed and cooled to room temperature by quenching in an ice bath. One mL of the internal standard solution (methylparaben) was added and the sample was subjected immediately to GLC analysis. The pH was measured at the beginning and end of each run, and no significant change was found.
- Buffers:
- All buffer solutions were prepared in deionized, distilled water and were adjusted to an ionic strength of 0.5 with potassium chloride. Buffer solutions in the pH range of 2.0 to 7.4 were prepared by combining various amounts of 0.1 M citric acid and 0.2 M dibasic sodium phosphate stock solutions.
- Details on test conditions:
- Amounts of methenamine equal to 0.75 mg/mL were weighed and placed in volumetric flasks. At time zero, the methenamine was dissolved in buffer solutions of pH 2.0, 2.4, 3.4, 4.6, 5.1, 5.5, 5.8 or 7.4 preivously equilibrated to 37.5°C. After dilution with the respective buffers, 10.0 mL samples were removed and placed in 16 x 125 mm culture tubes with polytef-lined screw caps. These tubes were placed into a constant temperature water bath.
Hexamethylenetetramine at 0.75 mg/mL was also studied kinetically at 47, 57 and 67 °C in pH 2.0, 5.1 and 7.4 buffers. - Duration:
- 6 h
- Initial conc. measured:
- 0.75 g/L
- Number of replicates:
- not indicated
- Positive controls:
- no
- Negative controls:
- no
- Statistical methods:
- Arrhenius plot
- Preliminary study:
- no preliminary study
- Test performance:
- good test performance
- Transformation products:
- yes
- No.:
- #1
- No.:
- #2
- Details on hydrolysis and appearance of transformation product(s):
- Formation of Formaldehyde and ammonia.
- Key result
- pH:
- 2
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.43 h-1
- DT50:
- 1.6 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9978
- Key result
- pH:
- 2.4
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.33 h-1
- DT50:
- 2.12 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9848
- Key result
- pH:
- 3.4
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.22 h-1
- DT50:
- 3.09 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9920
- Key result
- pH:
- 4.6
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.19 h-1
- DT50:
- 3.73 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9993
- Key result
- pH:
- 5.1
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.08 h-1
- DT50:
- 8.29 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9882
- Key result
- pH:
- 5.5
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.06 h-1
- DT50:
- 10.9 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9935
- Key result
- pH:
- 5.8
- Temp.:
- 37.5 °C
- Hydrolysis rate constant:
- 0.05 h-1
- DT50:
- 13.8 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9935
- Key result
- pH:
- 7.4
- Temp.:
- 37.5 °C
- Type:
- other: not applicable
- Remarks on result:
- other: No observable degradation over the time interval studied.
- Key result
- pH:
- 2
- Temp.:
- 47 °C
- Hydrolysis rate constant:
- 1.15 h-1
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9985
- Key result
- pH:
- 2
- Temp.:
- 57 °C
- Hydrolysis rate constant:
- 4.19 h-1
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: r2: 0.9985
- Other kinetic parameters:
- pH 2 (67°C): k = 11 h-1
pH 5.1 (47°C): k = 0.11 h-1
pH 5.1 (57°C): k = 0.23 h-1
pH 5.1 (67°C): k = 0.43 h-1 - Details on results:
- The kinetics of degradation also were measured at 47, 57 and 67°C, and the reaction obeyed the Arrhenius relationship. At pH 2.0, the activation energy was calculated to be 23.5 kcal/mole; at pH 5.1, it was 12.0 kcal/mole.
- Validity criteria fulfilled:
- yes
- Conclusions:
- The conversion of methenamine is pH dependent.
- Executive summary:
The kinetics of degradation of methenamine were studied in citrate-phosphate buffers between pH 2.0 and 7.4 at 37°C. Gas Chromatography was used to monitor the rate of hydrolysis. The conversion rate of methenamine to formaldehyde was found to be pH dependent in the buffers of constant ionic strength, with the reaction half-life decreasing from 13.8 h at pH 5.8 to 1.6 h at pH 2.0. The kinetics of degradation also were measured at 47, 57 and 67°C, and the reaction obeyed the Arrhenius relationship. At pH 2.0, the activation energy was calculated to be 23.5 kcal/mole; at pH5.1, it was 12.0 kcal/mole.
Reference
Description of key information
The conversion rate of methenamine to formaldehyde at a constant ionic strength was found to be pH dependent, with a reaction half-life decreasing from 13.8 h at pH 5.8 to 1.6 h at pH 2.0. The value below is given for pH 5.8.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 15 d
Additional information
The kinetics of degradation of methenamine (Strom, 1980) were studied in citrate-phosphate buffers between pH 2.0 and 7.4 at 37°C. Gas Chromatography was used to monitor the rate of hydrolysis. The conversion rate of methenamine to formaldehyde was found to be pH dependent in the buffers of constant ionic strength, with the reaction half-life decreasing from 13.8 h at pH 5.8 to 1.6 h at pH 2.0. The kinetics of degradation also were measured at 47, 57 and 67°C, and the reaction obeyed the Arrhenius relationship. At pH 2.0, the activation energy was calculated to be 23.5 kcal/mole; at pH 5.1, it was 12.0 kcal/mole.
After the release of the remaining substance from the waste water treatment plant into surface water, methenamine is expected to be further degraded hydrolytically to ammonia and formaldehyde. This needs to be considered especially for acidic receiving waters. Formaldehyde is classified as readily biodegradable (OECD 2002), and hence expected to be degraded by microbial activity. Ammonia is natural widely occurring, e.g. as excretion product of aquatic organisms. Ammonia is expected to volatilise from water to a certain degree. Under aerobic conditions it is transformed by nitrifying bacteria to nitrite and nitrate. As a realistic worst case for the degradation of methenamine a hydrolytical half-life of ~ 10 days is assumed. The half-life for the biodegradation of the hydrolysis products is estimated to be 15 days (according to the TGD, 2003). Hence, as realistic worst-case a half-life of 15 days, corresponding degradation rate constant of 0.046 d-1 is used for the exposure estimation.
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.