Chapter 6th:- Preparation Properties & Structures of Borazine, Diborane, Hydrazine, Interhalogens, Polyhalides, and Fluorides of Xenon
B.sc 1st year Book
(Page 5)
Individual Members
(A) Compounds of the AX type :
Iodine monochloride, ICI
Preparation :
(i) It is prepared by adding iodine to liquid chlorine and the mixture is kept at 35∘C for 24 hours to ensure a complete reaction.
I2+Cl2⟶2Cl
It is obtained as a dark liquid that solidifies on long-standing at room temperature.
(ii) It is also prepared by heating iodine with potassium chlorate.
KClO3+I2⟶KIO3+ICl
(iii) It is also formed in an aqueous solution when hydrochloric acid reacts with a mixture of potassium iodide and potassium iodate.
6HCl+KIO3+5KI⟶ KKCl + 3H2O + 3l2
KIO3+2l2+6HCl⟶KCl+5Cl + 3H2O
The reaction is quantitative and the two stages can be observed by the appearance and disappearance of the red colour of the free iodine.
Properties:
(i) It is a dimorphic solid. Its stable form is b-form which is ruby red needle-like crystals, m.p. 27.2∘C and the metastable form is b-form which is a red rhombic solid, m.p.14∘C and b.p. 97.4∘C. These two forms are identical in a gaseous state. These can be separated by cooling the liquid 1Cl below 14∘C and by adding to the liquid a crystal of either of the two forms.
(ii) Some metal chlorides like those of potassium, rubidium, caesium, and ammonium dissolve in the liquid iodine monochloride to form polyhalides.
KCl+ICl⟶KlCl2
ICl⟶KICl2CsilC2
while LiCl1NaCl and BaCl2 are insoluble in liquid ICl.
(iii) It is readily hydrolyzed by water (in a neutral solution).
5ICl+3H2O⟶5HCl+HI+2l2
(iv) It reacts with alkali to liberate Iodine.
5ICl+6NaOH⟶5NaCl+NaIO3+2I2+3H2O
(v) On electrolysis, Iodine is set free at the cathode and chlorine at the anode thereby indicating that the compound is a chloride of monovalent iodine (1+).
2Cl⟶1+ + ICl2−
At Cathode :21+ + 2e− ⟶ I2
At Anode : 2Cl2− − 2e− ⟶ I2+2Cl2
Therefore lig. ∣Cl is used as an ionizing solvent in which the heavier alkali-metal chlorides (KCl, RbCl, CsCl) dissolve.
(vi) It reacts with AlCl3 and AgClO4 in nitrobenzene.
AlCl3 + ICl ⟶ H+ + (AlCl4)−
At Anode : AgClO4+ICl⟶AgCl+IClO4
(vii) In strong hydrochloric acid it forms HICl2.
H+ + Cl+ + Cl ⟶ H+ + HCl2−
(viii) It reacts with many metals such as Mg, Ca, Ni, Cu, Zn, Fe, Co, etc. to form chlorides.
(ix) It converts acetanilide into 4−iodo ocetahylides and salicylic acid into 3,5 di-iodosalicylic acid.
(x) ICl forms charge transfer-type complexes with organic bases like pyridine and dioxane.
Chlorine monofluoride, CIF
Preparation :
(i) By the direct combination of Cl2and F2: Ruff (1928) obtained it by the direct combination of the elements at 250∘C in a copper tube.
Cl2+F2⟶2CF
(ii) It may also be prepared by the reaction of Cl2 with HF or CF3.
HF+Cl2⟶HCl+CIF
ClF3+Cl2⟶3ClF
Properties :
(i) It is a colourless gas of characteristic smell. It can be liquefied and solidified only at low temperatures.
(ii) Its m.p. is −155.6∘C and b.p. is 100.1∘C
(iii) it dissociates on heating.
2CIF⟶Cl2+F2
(iv) It combines with carbon monoxide to form carbonyl chloro fluoride.
CIF+CO⟶ COCIF
(v) It reacts with NaCl and SiO2 as :
NaCl+CIF⟶NaF+Cl2
SiO2+4ClF⟶SiF4+2Cl2O
(vi) It reacts with a number of metals, even more vigorously than F2. It inflames cotton wool and filter paper in the same way as F2.
Bromine mono fluoride, BrF
Preparation:
It may be prepared by saturating bromine with fluorine or by the action of bromine trifluoride on bromine.
Br2+F2⟶2BrFBrF3+Br2⟶3BrF
Properties :
(i) It is a reddish brown liquid, b.p. 23∘C and mp−33∘C.
(ii) It is unstable and decomposes as follows :
(ii) It is unstable and decomposes as follows :
3BrF⟶BrF3+Br2
(iii) It is very reactive and reacts with almost all metals.
(iv) It reacts with Sulphur slowly while phosphorus burns vigorously.
(v) It also reacts with CO2 and SO2 on warming.
(vi) It reacts with water to form oxygen and ozone.
(iv) It reacts with Sulphur slowly while phosphorus burns vigorously.
(v) It also reacts with CO2 and SO2 on warming.
(vi) It reacts with water to form oxygen and ozone.
Bromine mono chloride, BrCl
Preparation:
It may be prepared by passing chlorine gas into liquid bromine cooled below at 10∘C.
Br2+Cl2⟶2BrCl its existence was proved in 1928 by spectrophotometric measurements.
Properties :
(i) It is a highly volatile and reddish-yellow mobile liquid.
(ii) it is freely soluble in water, ether, carbon disulphide, and carbon tetrafluoride,
(iii) It decomposes at 10∘C.
(ii) it is freely soluble in water, ether, carbon disulphide, and carbon tetrafluoride,
(iii) It decomposes at 10∘C.
2BrCl⟶Br2+Cl2
(iv) Its vapours are irritating to the eyes.
Related More: Structure of AB type of interhalogen Molecules