Chlorine and oxygen can bond in numerous
chlorine monoxide, ClO, chlorine(II) oxide
chlorine dioxide, ClO
2, chlorine(IV) oxide
chlorine trioxide, ClO3,
dichlorine monoxide, Cl2O, chlorine(I) oxide
ClO dimer, Cl2O2,
chloryl chloride, ClO2Cl,
chlorine chlorite, ClOClO,
oxide; ClO dimer
where otherwise noted, data are given for materials in their standard state (at 25 °C 77 °F 100 kPa).
Chlorine peroxide (also
identified as dichlorine dioxide or dimer) is a molecular
compound with method ClOOCl. Chemically, it is a dimer of
the chlorine monoxide radical (ClO). It is vital in the
formation of the ozone hole. Chlorine peroxide catalytically changes
ozone into oxygen when it is exposed by ultraviolet light.
is an oligomer containing of
two structurally similar monomers joined by bonds
that can be whichever strong or weak, covalent and intermolecular. The term homodimer is used when the two
molecules are matching and heterodimer when
they 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 depletion defines two related phenomena observed since the late
1970. a steady failure of about four percent in the total amount of ozone in Earth’s stratosphere and a much larger springtide
decrease in stratospheric ozone around Earth’s glacial regions. The latter
phenomenon is referred to as the ozone
hole. There are also springtime polar tropospheric ozone
depletion events in addition to these stratospheric phenomena.
Chlorine peroxide can be produced by laser or ultraviolet photolysis of
the chlorine molecule with ozone. The lasers used to break up the chlorine
molecule into atoms can be an excimer
laser at 248, 308, or 352 nm wavelength. Difluorodichloromethane (CF2Cl2)
can also act as a source of chlorine atoms for the formation of the
peroxide. Microwave discharge can also break up chlorine molecules into
atoms that react with ozone to make chlorine peroxide.
hv ? 2Cl
Cl + O3 ? O2 + ClO
+ M ? ClOOCl
+ h? ? Cl
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 banned
in developed countries in 1996, and developing countries in 2010 due to
concerns about its damaging impact to the ozone layer.Its only allowed usage is as fire
retardant 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.
An excimer laser, sometimes more
correctly 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.
Chlorine peroxide absorbs ultraviolet light with a maximum absorbing
wavelength of 245 nm. It also absorbs longer wavelengths up to 350 nm
to 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 Å
long. The ClOO bond angle is 110.1, and the dihedral
angle between the two Cl?O?O planes is 81
angle is the angle between two intersecting planes. In chemistry it is the angle
between planes through two sets of three atoms, having two atoms in common.
In solid geometry it is defined as
the union of a line and two half-planes that have this
line as a common edge. In higher dimension,
a dihedral angle represents the angle between two hyper planes.
Chalorine Peroxide Isomers
We report ab initio calculations of the
molecular structures of the various Cl2O2 isomers,
transition states, vibrational frequencies and vertical excitation energies, as
well as the relative energies of the Cl2O2 isomers
with respect to 2ClO, ClOO + Cl and OClO + Cl dissociation channels employing
up to the CCSD level of theory. Our best theoretical estimate for the
dissociation wave number D of
chlorine-peroxide, dichloride-dioxide ClOOCl relative to 2ClO is 6825
cm (including harmonic zero-point energy correction), compared to recent
experimental estimates in the range 5700–7000 cm, thus favouring the higher
values. 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 with
respect to the chlorine peroxide ClOOCl when large basis sets with diffuse
functions are used, and ClClO2 is predicted to be about hc700 cm?1 lower in
energy than ClOOCl (including harmonic zero-point energy correction). However,
ClClO2 is not assumed to be significant for the ClO
self-reaction due to the high barrier to association. The isomerisations appear
also unlikely under stratospheric conditions, as the transition states
optimised at CCSD level of theory are found to lie high above the reactants. We
also discuss the relation to recent research on parity violation and
stereomutation tunnelling in this molecule.
Bond strength of chlorine peroxide
The bond strength of chlorine peroxide (ClOOCl) is
studied by photoionization mass spectrometry. The experimental results are
obtained from the fragmentation threshold yielding ClO+ which is observed at
11.52 +/- 0.025 eV. The O-O bond strength D(o) is derived from this value in
comparison 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 examine
the equilibrium constant K for chlorine peroxide formation via dimerization of
ClO in the stratosphere. This yields an approximation for the equilibrium
constant in the stratospheric temperature regime between 190 and 230 K of the
form K 1.92 x 10^-27 cm3 molecules x e^(8430 K/T). This value of K is lower
than current reference data and agrees well with high altitude aircraft measurements
within their scattering range. Considering the error limits of the present
experimental results and the resulting equilibrium constant, there is agreement
with previous works, but the upper limit of current reference values appears to
be too high. This result is discussed
along with possible atmospheric implications.