Cyanic acid
(the isomer of fulminic acid) is an unstable (explosive), poisonous, volatile,
clear liquid with the structure of H-O-C¡ÕN (the oxoacid formed from the
pseudohalogen cyanide), which is readily converted to
cyamelide and fulminic
acid. There is another isomeric cyanic acid with the
structure of H-N=C=O, called isocyanic acid. Cyanate group (and isocyanate group) can react with itself.
Cyanuric acid (also called pyrolithic acid), white monoclinic crystal with
the structure of [HOC(NCOH)2N], is the trimer
of cyanic acid. The
trimer
of isocyanic acid
is called biuret.
- Cyanic acid:
H-N=C=O
or H-O-C¡ÕN
- Fulminic acid: (H-C=N-O)
or H-C¡ÕN-O
- Isocyanic acid:
H-N=C=O
- Cyanuric acid:
HOC(NCOH)2N
- Biuret:
(NH2)CO)2 NH
Cyanic acid hydrolyses to ammonia and carbon dioxide in
water. The salts and esters of cyanic acid are cyanates. But esters of
normal cyanic acid are not known. The salts and esters of isocyanic acid are
isocyanates. The isocyanate group reacts with the hydroxyl functional group to form a urethane linkage.
Diisocyanates
(or polyisocyanates) are monomers for polyurethane production. Polyurethane is
made from a variety of diisocyanates in conjunction with polyether and polyester
polyols as co-reactants by addition polymerization which needs at least two
-N=C=O groups. Polyurethanes are widely used in the manufacture of flexible and
rigid foams, fibres, coatings, and elastomers. If isocyanate monomer is polymerized
with amine group,
polyurea is produced. Cyanates (or Isocyanates) are readily
reacts with various
form of amine (including ammonia, primary-, secondary-amines, amides and ureas)
and hydroxyl functional group. They are used in the synthesis
for the target molecules such as pharmaceuticals, pesticides, textile softener, lubricants and industrial
disinfectants. They can convert to polycyclic compounds such as hydantoins
and imidazolons. They are used as plastic additives and as heat treatment salt
formulations for metals.
Thiocyanate is a salt or ester of thiocyanic acid (HSCN). Aqueous solutions of
thiocyanic acid , also called sulfocyanic acid, are very strong acids of the
equilibrium mixture of thiocyanic and isothiocyanic. Thiocyanates are bonded
through the sulfur(s) with the structure R-S-C¡ÕN or the isomeric R-N=C=S
(isothiocyanates). Thiocyanates are bonded through the sulfur(s) which replace
for the oxygen (O) atom. Thiocyanates are the sulfur analog of isocyanates.
Organic as well as metallic thiocyanates [CuSCN, Ca(SCN)2, NaSCN, KSCN] are very
versatile compounds. Isothiocyanates act as electrophiles with the carbon atom as the
electrophilic center. They have wide range of applications as an intermediate to
create a desired chemical compound through a series
of chemical reactions for the industrial field includingf fungicide, bactericide, wood
preservative, pharmaceutical and plastic and rubber. Some isothiocyanates are used in freezing
solutions, fabric dyeing, electroplating, steel pickling, printing, and corrosion
inhibitor against acid gases. They are used in photography industry as a stabilizer
or accelerator. Certain isothiocyanates, such as phenethyl isothiocyanate and sulforaphane
are known as chemopreventive agents against the development and proliferation of cancers.
Allyl isothiocyanate, called mustard oil,
shows also
anti-tumor and anti-oxidant properties by inducing
the activity of phase II detoxification enzymes in the urinary bladder.
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