Iodine is a
nonmetallic halogen element in Group 17 of periodic table; atomic number 53;
atomic mass 126.9; melting point ca 114 C; boiling point ca 184 C; specific
gravity 4.93 g/cm3; oxidation states: 7,5,1,-1; [Kr] 4d10 5s2 5p5.
Iodine is a nearly black poisonous, corrosive solid at room temperature and
readily sublimes to a deep violet vapour, the colour of which is responsible for
its name from Greek. It is insoluble in water, soluble in common solvents.
Iodine is required in small amounts in human body for the function of the
thyroid gland. Iodine forms many important compounds of iodine such as
iodine(V)oxide, potassium iodide, iodine trichloride and iodoform of an Iodine
containing organic compound.
name, iodate indicates any salt of iodic acid containing the
KIO3 (potassium iodate)
and NaIO3 (sodium iodate) are
the most important salts. Whereas, iodide indicates any compound of iodine with
a more electropositive element or group such as such as
CH3CH2I or any binary
compound of iodine which may contain the I- radical and which may
be considered to be derived from hydriodic acid (HI); KI and NaI are examples.
iodine is reduced to iodide, absorbed in the intestines, and later taken up from
the bloodstream by the thyroid gland for incorporation into thyroid hormones.
Iodine is applied in the treatment of thyrotoxic crisis to produce a thyroid
gland of firm texture suitable for operation, it avoids the increased
vascularity and friability of the gland with increased risk of haemorrhage.
Iodine has powerful bactericidal activity. It is used is used for disinfecting
skin and for the treatment of minor wounds and abrasions. Iodine has been used
in the purification of drinking water in case of amoebicidal and bactericidal
emergencies. Iodine is used as a component in germicides and
disinfectants with surfactants to carry iodine. Iodine is used in the
treatment of herpes simplex, keratoscleritis and preventing the development of
iodide compounds are soluble in water and hygroscopic except a few inorganic
iodides such as copper iodide. Their refractive indexes and specific gravities
are higher than the corresponding chlorine and bromine analogues. The important
iodides commercially are potassium iodide (KI), sodium iodide (NaI), hydrogen
iodide (HI), and polyiodides.
sodium Iodide are used in photography and as analytical reagents. They are used
in the measurement of the energy of gamma rays, by measuring the amplitude of
pulses of light generated by electrons which are excited by the gamma rays. They
are used as nutrition supplements to prevent goitre and other iodine deficiency
in human body. They are used in organic synthesis as well. Potassium iodide has
been used as a mucolytic agent. Potassium iodide is used as a heat stabilizer
and a catalyst in synthetic fiber manufacturing.
acid is the aqueous pale yellow solution of gas hydrogen iodide; the solution
of 59% hydrogen iodide has constant-boiling. It is a strong acid and reducing
agent used as raw materials for pharmaceuticals. analytical reagent as well as
in organic synthesis and making iodine salts.
iodate compounds, prepared generally by the oxidation of iodine with iodic acid
or by electrolytic oxidation of iodide solutions, are stable oxidizers at room
temperature though they lose oxygen at higher temperatures. Iodic acid
(hydrogen iodate), a white crystalline
powder, is a strong inorganic acid; highly corrosive oxidizing agent; decomposes
at 110 C. It is used as a reducing agent in organic synthesis. Metallic iodates
are explosive or flammable when contact with organic combustible materials. The
important iodates commercially are potassium iodate and calcium iodate; white,
odorless crystaline powder soluble in water, insoluble in alcohol. They are used
as analytical reagents and in the manufacture of disinfectants, antiseptics,
deodorants, medicines and other iodine compounds as well as oxidation of sulphur
dyes. They are used in baking ingredient conditioner and as animal feed and food
supplement for the treatment of their deficiency.
iodines are very useful reagents as they have lower heat of formation than
chlorine or bromine analogues. Aliphatic Iodides are used as alkylating agents
in synthetic organic chemistry. Iodoform is a simple structural compound;
greenish yellow hexagonal solid with a strong, penetrating odor; containing
about 96 per cent of iodine; melting point 119 C; soluble in chloroform and
ether and somewhat in alcohol and water: used as a topical anti-infective,
applied to the skin. Iodoacetic acid is used in biochemical research; it
alkylates free thiol groups but not disulfide bridges. methyl iodide, also
called iodomethane, is a colorless liquid that turns brown on exposure to light;
used in microscopy and in testing for pyridine. It is irritating to skin and
mucous membranes and is a suspected carcinogen. Ethylene diamine dihydroiodide
is used in animal feeds to prevent deficiency of iodine. Iodine organic
compounds are useful in dye industry for the high bright colors as well as
pharmaceutical industry. They are important for the production of X-ray contrast
media and for the formulating antiseptics.