Chlorine peroxide (Cl2(O2)) (12292-23-8) Physical and Chemical Properties
Chlorine peroxide (Cl2(O2))
An inorganic chlorine peroxide that functions as a reactive intermediate in halogen–oxygen chemistry, relevant to laboratory synthesis, mechanistic studies and specialized process development.
| CAS Number | 12292-23-8 |
| Family | Inorganic peroxides / halogen oxides |
| Typical Form | Reactive gas or vapor |
| Common Grades | EP |
Chlorine peroxide is an inorganic peroxide of the dichlorine–dioxygen class; it is commonly represented as \(\ce{Cl2O2}\) and structurally described by the peroxy-linked motif \(\ce{Cl-O-O-Cl}\) (SMILES: O(OCl)Cl). The molecule is a neutral, covalently bonded small species (computed covalent unit count = 1, formal charge = 0) with a single O–O peroxy linkage that dominates its electronic and reactive behaviour. The peroxy bond imparts a low bond dissociation energy relative to normal single bonds and confers strong oxidizing character; the chlorine atoms are formally in oxychlorine environments that can give rise to electrophilic chlorine transfer and generation of oxychlorine radicals under energetic or photochemical activation.
Electronic and physicochemical descriptors indicate modest lipophilicity and limited polar surface: computed XLogP3 = 1.7 and topological polar surface area = 18.5 Å^2; hydrogen-bond donor count = 0 and hydrogen-bond acceptor count = 2. These descriptors are consistent with a small, neutral oxidant that is not strongly solvated by hydrogen-bonding but can engage in polar interactions via the oxygen atoms. Thermochemical and photochemical lability (weak O–O bond) typically results in rapid decomposition pathways on heating, in the presence of light, or in contact with reducing substrates; hydrolysis in protic media produces oxychlorine species rather than classical stable ions.
Commercial availability is limited and specialized; Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting or Decomposition Point
No experimentally established value for this property is available in the current data context.
Solubility in Water
No quantitative solubility value is available in the current data context. Qualitatively, inorganic peroxides with peroxy linkages such as \(\ce{Cl2O2}\) are chemically reactive toward water: aqueous contact tends to induce hydrolytic cleavage of the O–O or Cl–O bonds and formation of oxychlorine species (for example \(\ce{HOCl}\) and related transient products). Consequently, equilibrium solubility is complicated by concurrent chemical transformation, and any practical aqueous handling will reflect hydrolysis kinetics as much as intrinsic solubility.
Solution pH (Qualitative Behavior)
No experimentally established pH value for standard aqueous solutions is available in the current data context. Qualitatively, aqueous reaction products from hydrolysis are expected to be acidic or acidifying (formation of oxychlorine acids such as \(\ce{HOCl}\) and related species), so solutions formed by dissolution or hydrolysis of \(\ce{Cl2O2}\) tend toward acidic, oxidizing conditions. The observed solution \(\mathrm{pH}\) will depend on concentration, extent of hydrolysis, and buffering capacity of the medium.
Chemical Properties
Acid–Base Behavior
\(\ce{Cl2O2}\) is not a classical Brønsted acid or base in its intact molecular form; acid–base phenomena arise primarily from its hydrolysis products. Proton transfer chemistry is dominated by oxychlorine species generated on cleavage of Cl–O or O–O bonds (for example formation of \(\ce{HOCl}\) and other chlorinated oxyacids/oxyanions under appropriate conditions). As a consequence, acid–base equilibria are context-dependent: in aqueous environments the system behaves as an oxidizing acidic solution rather than as a simple conjugate acid/base pair.
Reactivity and Stability
The defining chemical characteristic is the peroxy (O–O) linkage: this bond is thermally and photochemically labile and is a primary pathway for decomposition to chlorine-containing radicals and molecular oxygen. The molecule is a strong oxidant and reacts readily with reducing organic and inorganic substrates, with transition-metal surfaces that catalyze decomposition, and with light or heat to produce reactive intermediates. It is therefore considered chemically unstable relative to typical covalent dihalogen oxides and requires precautions against uncontrolled decomposition. Reaction products may include chlorine-containing species (chlorine atoms, \(\ce{Cl2}\), oxychlorine radicals) and oxygen; in the presence of water, hydrolytic and secondary oxidative transformations dominate the chemistry.
Molecular and Ionic Parameters
Formula and Molecular Weight
- Molecular formula: \(\ce{Cl2O2}\)
- Molecular weight: \(\mathrm{102.90\ g\ mol^{-1}}\)
- Exact mass (computed): \(\mathrm{101.9275346\ u}\)
- Monoisotopic mass (computed): \(\mathrm{101.9275346\ u}\)
- Topological polar surface area (computed): 18.5 Å\(^2\)
- XLogP3 (computed): 1.7
These computed parameters indicate a low-molecular-weight inorganic peroxide with limited polar surface but sufficient polarity at the oxygen sites to engage in reactive solvation and hydrolysis.
Constituent Ions
No constituent ions in the isolated molecule — \(\ce{Cl2O2}\) is a neutral covalent species (formal charge = 0). Ionic speciation may arise only after chemical transformation (e.g., hydrolysis to form oxychlorine anions such as \(\ce{ClO^-}\) under specific conditions).
Identifiers and Synonyms
Registry Numbers and Codes
- CAS Registry Number: 12292-23-8
- InChI:
InChI=1S/Cl2O2/c1-3-4-2 - InChIKey:
MAYPHUUCLRDEAZ-UHFFFAOYSA-N - SMILES:
O(OCl)Cl - ChEBI: CHEBI:35927
- DSSTox Substance ID: DTXSID001310193
- Nikkaji Number: J3.233.696E
- Wikidata: Q2679386
(Where SMILES, InChI and InChIKey are presented as machine-readable identifiers for structure representation and cheminformatics workflows.)
Synonyms and Common Names
Depositor-supplied synonyms and common names available in the present context include: - 12292-23-8 - Chlorine peroxide (Cl2(O2)) - RefChem:125329 - Dichlorine dioxide - chlorooxy hypochlorite - Chlorperoxyd - ClOOCl - Dioxygen dichloride - Cl2O2 - bis(chloridooxygen)(O--O) - SCHEMBL180347 - CHEBI:35927 - DTXSID001310193 - Q5272473
Note: historical or removed synonyms have been recorded but are not reproduced here beyond the active depositor-supplied set above.
Industrial and Commercial Applications
Functional Roles and Use Sectors
No concise application summary is available in the current data context; in practice this substance is selected based on its general properties described above. At the class level, small inorganic peroxides and oxychlorine tautomers are used primarily as reactive oxidants in research contexts and are of interest in atmospheric chemistry and mechanistic studies of chlorine-driven oxidation. Due to instability and hazardous reactivity, routine large-scale industrial applications are uncommon; use is typically restricted to controlled laboratory or specialized research settings.
Typical Application Examples
No experimentally established use profiles are available in the current data context. Typical, generalized examples consistent with the chemical class include: mechanistic probes for oxidative processes, reagents in exploratory synthetic oxidations carried out under strict controls, and role as atmospheric transient species in photochemical and environmental studies.
Safety and Handling Overview
Health and Environmental Hazards
Chlorine peroxide is an oxidizing, reactive chemical with potential for acute irritation and corrosive effects on contact with skin, eyes and mucous membranes. Decomposition or hydrolysis can generate chlorine-containing oxidants and potentially chlorine gas; inhalation of decomposition products presents a respiratory hazard. Environmental hazards stem from the formation of reactive chlorine species that are toxic to aquatic organisms and that can contribute to local oxidative stress in ecosystems. Given the potential for energetic decomposition, contact with organic materials, reducing agents, or catalytic surfaces should be avoided.
For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
Storage and Handling Considerations
Handling should follow conservative practices for unstable inorganic peroxides and reactive halogen oxy-compounds: store in a cool, well-ventilated, dark location away from heat sources, strong reducing agents, combustible materials and organic contaminants. Containers and transfer equipment should be inert and clean of catalytic metal residues; minimize mechanical shock and exposure to light. Use appropriate personal protective equipment (gloves, eye protection, respiratory protection where necessary) and engineering controls (local exhaust ventilation, explosion-proof equipment where applicable). For spill or decomposition incidents, isolate area, evacuate nonessential personnel, and consult emergency procedures specific to oxidizers and chlorine-containing decomposition products.
