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Diss Factsheets
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EC number: 231-959-5 | CAS number: 7782-50-5
- 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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Phototransformation in air
Administrative data
Link to relevant study record(s)
Description of key information
In the atmosphere, Cl2 will degrade during daylight, with half-lives ranging from minutes to several hours, depending on latitude, season, and time of day.
Key value for chemical safety assessment
Additional information
The main reaction of molecular chlorine emitted to the atmosphere is photolysis, which generates atomic chlorine:
Cl2 + hv => 2Cl°
Photolysis occurs only during daylight hours. The estimated half-life for this process is approximately 2-4 hours, which is consistent with an atmospheric lifetime of less than 0.001 year (Doc IIIA, Section A7.3.2/02). The chlorine atoms formed by that process can then react with other species present in the atmosphere.
Reaction of atomic chlorine with saturated hydrocarbons:
Cl° + R-H => HCl + R°
HCl formed by this process can be washed out by rain water or react with hydroxyl radicals OH° to regenerate atomic chlorine:
HCl + OH° => H2O + Cl°
Reaction of atomic chlorine with unsaturated hydrocarbons:
Atomic chlorine can also react with unsaturated organic compounds by addition to unsaturated sites. This reaction can lead to the formation of chloro-organic compounds in the atmosphere.
Reaction of atomic chlorine with ozone
Atomic chlorine can also react with ozone, as shown below:
Cl° + O3 => ClO + O2
ClO + HO2° => HOCl + O2
HOCl can be photolysed to regenerate Cl°.
HOCl + hv => HO + Cl°
These reactions indicate a participation of the catalytic cycle of ozone destruction. Overall, there is competition between the reaction of chlorine atoms with hydrocarbons and ozone.
Troposphere ozone formation potential
Atomic chlorine is a very reactive species and much more reactive than molecular chlorine. It reacts with non-methane hydrocarbons (NMHC) and some of the reaction products can form peroxy radicals which will contribute to the formation of ozone. Atomic chlorine can also substitute hydrogen atoms from aldehydes to form hydrochloric acid. In the case of acetaldehydes, the acetyl radical can then add oxygen and nitrogen to form peroxy acetyl nitrate (PAN). Peroxy radicals and PAN are two principal marker species of photochemical smog and add to the formation of ozone. On the other side, chlorine can also react with ozone, see reaction. However, the net effect of chlorine on the ozone concentration is still under discussion.
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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