Chlorine Oxides Chlorine and oxygen can bond in numerousways:· chlorine monoxide, ClO, chlorine(II) oxide· chlorine dioxide, ClO2, chlorine(IV) oxide· chloroperoxyl, ClOO· chlorine trioxide, ClO3,chlorine(VI) oxide· dichlorine monoxide, Cl2O, chlorine(I) oxideThree dichlorinedioxides: ClO dimer, Cl2O2, chlorine peroxide chloryl chloride, ClO2Cl, chlorine(0,IV) oxide chlorine chlorite, ClOClO, chlorine(I,III) oxide Chlorine Peroxide Names IUPAC name Dichlorine dioxide Other names Chlorine(I) oxide; ClO dimer Identifiers CAS Number · 12292-23-8 3D model · Interactive image ChemSpider · 109895 PubChem CID · 123287 InChI SMILES Properties Chemical formula Cl2O2 Molar mass 102.905 g/mol Except where otherwise noted, data are given for materials in their standard state (at 25 °C 77 °F 100 kPa). Chlorine peroxide (alsoidentified as dichlorine dioxide or dimer) is a molecularcompound with method ClOOCl. Chemically, it is a dimer ofthe chlorine monoxide radical (ClO).
It is vital in theformation of the ozone hole. Chlorine peroxide catalytically changesozone into oxygen when it is exposed by ultraviolet light.DimerA dimeris an oligomer containing oftwo structurally similar monomers joined by bondsthat can be whichever strong or weak, covalent and intermolecular. The term homodimer is used when the twomolecules are matching and heterodimer whenthey are not. The reverse of dimerisation is frequently called dissociation. When two oppositely charged ions associate into dimers,they are referred to as Bjerrum sets.Ozone HoleOzone depletion defines two related phenomena observed since the late1970. a steady failure of about four percent in the total amount of ozone in Earth’s stratosphere and a much larger springtidedecrease in stratospheric ozone around Earth’s glacial regions.
The latterphenomenon is referred to as the ozonehole. There are also springtime polar tropospheric ozonedepletion events in addition to these stratospheric phenomena. ProductionChlorine peroxide can be produced by laser or ultraviolet photolysis ofthe chlorine molecule with ozone.
The lasers used to break up the chlorinemolecule into atoms can be an excimerlaser at 248, 308, or 352 nm wavelength. Difluorodichloromethane (CF2Cl2)can also act as a source of chlorine atoms for the formation of theperoxide. Microwave discharge can also break up chlorine molecules intoatoms that react with ozone to make chlorine peroxide. ChemicalReactions Cl2 + hv ? 2Cl Cl + O3 ? O2 + ClO 2ClO + M ? ClOOCl + M ClOOCl + h? ? Cl + ClO2 ClO2 + M ? Cl + O2 Dichlorodifluoromethane is a colorless gas usually sold under the brand name Freon-12, and a chlorofluorocarbonhalomethane (CFC) used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was bannedin developed countries in 1996, and developing countries in 2010 due toconcerns about its damaging impact to the ozone layer.Its only allowed usage is as fireretardant in submarines and aircraft. It is soluble in many organic solvents.Dichlorodifluoromethane was one of the original propellants for Silly String.
R-12 cylinders are colored white.Excimer LaserAn excimer laser, sometimes morecorrectly called an exciplex laser,is a form of ultraviolet laser which is commonly used in the production of microelectronic devices, semiconductor based integrated circuits or “chips”, eye surgery, and micromachining. PropertiesChlorine peroxide absorbs ultraviolet light with a maximum absorbingwavelength of 245 nm. It also absorbs longer wavelengths up to 350 nmto a lesser extent. This is important as ozone absorbs up to 300 nm. The Cl?O bond length is 1.704 Å, and the O?O bond is 1.426 Ålong.
The ClOO bond angle is 110.1, and the dihedralangle between the two Cl?O?O planes is 81Dihedral AngleA dihedralangle is the angle between two intersecting planes. In chemistry it is the anglebetween planes through two sets of three atoms, having two atoms in common.In solid geometry it is defined asthe union of a line and two half-planes that have thisline as a common edge. In higher dimension,a dihedral angle represents the angle between two hyper planes.Chalorine Peroxide IsomersWe report ab initio calculations of themolecular structures of the various Cl2O2 isomers,transition states, vibrational frequencies and vertical excitation energies, aswell as the relative energies of the Cl2O2 isomerswith respect to 2ClO, ClOO + Cl and OClO + Cl dissociation channels employingup to the CCSD level of theory.
Our best theoretical estimate for thedissociation wave number D ofchlorine-peroxide, dichloride-dioxide ClOOCl relative to 2ClO is 6825cm (including harmonic zero-point energy correction), compared to recentexperimental estimates in the range 5700–7000 cm, thus favouring the highervalues. The chlorine chlorite structure ClOClO is found to be weakly bound by ?3400 cm?1 with respect to 2ClO. The chloryl chloride,chlorine peroxide ClClO2 is observed to be stabilised withrespect to the chlorine peroxide ClOOCl when large basis sets with diffusefunctions are used, and ClClO2 is predicted to be about hc700 cm?1 lower inenergy than ClOOCl (including harmonic zero-point energy correction). However,ClClO2 is not assumed to be significant for the ClOself-reaction due to the high barrier to association.
The isomerisations appearalso unlikely under stratospheric conditions, as the transition statesoptimised at CCSD level of theory are found to lie high above the reactants. Wealso discuss the relation to recent research on parity violation andstereomutation tunnelling in this molecule. Bond strength of chlorine peroxideThe bond strength of chlorine peroxide (ClOOCl) isstudied by photoionization mass spectrometry. The experimental results areobtained from the fragmentation threshold yielding ClO+ which is observed at11.52 +/- 0.
025 eV. The O-O bond strength D(o) is derived from this value incomparison to the first ionization energy of ClO, yielding D 298 = 72.39 +/-2.8 kJ mol. The present work provides a new and independent method to examinethe equilibrium constant K for chlorine peroxide formation via dimerization ofClO in the stratosphere. This yields an approximation for the equilibriumconstant in the stratospheric temperature regime between 190 and 230 K of theform K 1.
92 x 10^-27 cm3 molecules x e^(8430 K/T). This value of K is lowerthan current reference data and agrees well with high altitude aircraft measurementswithin their scattering range. Considering the error limits of the presentexperimental results and the resulting equilibrium constant, there is agreementwith previous works, but the upper limit of current reference values appears tobe too high. This result is discussedalong with possible atmospheric implications.