Iodine monochloride is the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula ICl. It is a red-brown compound that melts near room temperature. Because of the difference in the
electronegativityElectronegativity, symbol χ, is a chemical property that describes the ability of an atom to attract electrons towards itself in a covalent bond. An atom's electronegativity is affected by both its atomic weight and the distance that its valence electrons reside from the charged nucleus...
of
iodineIodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons....
and
chlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
, ICl is highly
polarIn chemistry, polarity refers to a separation of electric charge leading to a molecule having an electric dipole. Polar molecules can bond together due to dipole–dipole intermolecular forces between one molecule with asymmetrical charge distribution and another molecule also with asymmetrical...
and behaves as a source of I
+.
Preparation of iodine monochloride entails simply combining the halogens in a 1:1 molar ratio, according to the equation
- I2 + Cl2 → 2 ICl
When chlorine gas is passed through iodine crystals, one observes the brown vapor of iodine monochloride.
Iodine monochloride is the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula ICl. It is a red-brown compound that melts near room temperature. Because of the difference in the
electronegativityElectronegativity, symbol χ, is a chemical property that describes the ability of an atom to attract electrons towards itself in a covalent bond. An atom's electronegativity is affected by both its atomic weight and the distance that its valence electrons reside from the charged nucleus...
of
iodineIodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons....
and
chlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
, ICl is highly
polarIn chemistry, polarity refers to a separation of electric charge leading to a molecule having an electric dipole. Polar molecules can bond together due to dipole–dipole intermolecular forces between one molecule with asymmetrical charge distribution and another molecule also with asymmetrical...
and behaves as a source of I
+.
Preparation of iodine monochloride entails simply combining the halogens in a 1:1 molar ratio, according to the equation
- I2 + Cl2 → 2 ICl
When chlorine gas is passed through iodine crystals, one observes the brown vapor of iodine monochloride. Dark brown iodine monochloride liquid is collected. Excess chlorine converts iodine monochloride into
iodine trichlorideIodine trichloride is a compound of iodine and chlorine. It is bright yellow and in the solid state is present as a planar dimer I2Cl6, Cl2I2ICl2, with two bridging Cl atoms....
in a reversible reaction:
- ICl + Cl2 ICl3
Polymorphs
ICl has two
polymorphsPolymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to elemental solids...
; α-ICl which exists as black needles (red by transmitted light) with a
melting pointThe melting point of a solid is the temperature range at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point...
of 27.2 °C, and β-ICl which exists as black platelets (red-brown by transmitted light) with a melting point 13.9 °C.
Uses
ICl is a useful reagent in
organic synthesisOrganic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. It is used as a source of electrophilic iodine in the synthesis of certain aromatic iodides. It also cleaves C-Si bonds.
ICl will also add to the
double bondA double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...
in
alkeneIn organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s to give chloro-iodo
alkaneAlkanes, also known as paraffins, are chemical compounds that consist only of the elements carbon and hydrogen , wherein these atoms are linked together exclusively by single bonds without any cyclic structure...
s.
- RCH=CHR’ + ICl → RCH(I)-CH(Cl)R’
When such reactions are conducted in the presence of
sodium azideSodium azide is the chemical compound with the formula NaN3. This colourless azide salt is a common reagent in organic synthesis, and it is a component in many car airbag systems.-Structure:...
, the iodo-azide RCH(I)-CH(N
3)R’ is obtained.