compounds are the organometallic compounds having at least one direct C-Si
bond. They are described as any series of derivative of silicon that have at
least one alkyl or aryl group especially one containing C-Si bond. Examples
tetraethylsilane, trimethylvinylsilane, silanol, siloxides, silene,
1863, two scientist Friedal and Crafts frist synthesized the organosilicon
is made in high yield from silicon
tetrachloride and various organometal derivatives, notably ethylmagnesium halides
or ethyl-lithium. The first preparation of organosilicon compound in 1863
involved the use of diethylzinc.
from difficult nucleophilic and electrophilic cleavage of the Si-C bond
reffered to earlier ,tetraethylsilane decomposes on strong heating to give
ethane and Si-H bond; this dehydrosilation method is markedly catalyzed by metal oxides, and is
general for all alkyls other than methyl
in 1945 there had been direct synthesis of the chlorosilanes in the presence of
a catalyst establishing the modern organicsilicon industry. All of this has
created the conditions for the production of organic silicon with the
functional group. It is similar to most of organic compounds but also differ.
For example: The silicone -Si only contain single bond between the silicon
atoms . Simple types contain halosilcanes. For example:CH3SiCl (
trimethylchlorosilane) , silanol (CH3SiOH)
, silyl ethers (CH3)3Si-O-Si(CH3)3 and
compounds have special properties such as they are being able to polymerized in
to poly- siloxanes (silicones) ,are resistant to heat and water and have
electrical insulation properties and are being able to use for manufacturing of
silicone oil, silicone rubber and silicone resin.
are colourless or transparent liquids at room temperature. Are toxic and soluble in many organic solvents. Are
corrosive and prone to burn, produce
toxic fumes in the case of oxidants, fire and heat. Phenylsilane in contact
with steam produce toxic gasses. It is used as the water repellent, silicide
intermediates in industry and use in the synthesis of polymer organic silicide .in
the management of dangerous silicide as flammable liquids. Phenyl it is also
classified as the corrosive substance.
is naturally occurring chemical element and is 14th element in the
periodic table. It is a metalloid meaning it has the properties of both metal
and non-metal. It is second most abundant element in the earth crust after
oxygen. It readilys bounds with the oxygen and rarely found in nature in its
pure form. It is mosthy found in the form of silicon dioxide ( SiO2
) and silica better known as quartz which is most common component of sand.
Silicon and oxygen mix with reactive
metals, the result is the class of minerals called silicates which include granite, feldspar, mica. A silicate is the compound containing an anionic silicon
compound , hexafluorosilicate SiF6 2- type of
silicates also exist.
is a synthetic substance it is a synthetic polymer made up of silicon , oxygen
and other elements such as carbon and hydrogen. It is generally a liquid or
flexible rubber like plastic and has useful properties such as low toxicity and
high heat resistance. And also provides good electrical insulation. Silicones
are also known as the polysiloxanes
can be defined as polymers that include inert, synthetic compounds made up of
repeating units of ”siloxanes” which is a chain of alternating silicon atoms
and oxygen atoms frequently combined with carbon/hydrogen.
consist of inorganic silicon-oxygen backbone chain -Si-O-Si-O-Si- with organic side groups attach to silicon
atoms. These silicon atoms are tetravalent , so silicones ar.e polymers constructed
from monomers and have general chemical
can think silicon atom as having ”four hooks” that can link to other atoms
and oxygen atoms as having ‘two hooks” with all the links serves as the base
for integrated circuits (microchips).
compounds are organometallic compounds containing direct C-Si bonds. It
describes any series of derivative of silicon that have at least one alkyl or
aryl group , especially one containing atleast on C-Si bond. They act as a
monomer in the formation of the silicones. SILICONES are the polymers of the
The organosilicon compounds are derived by the
direct reaction of alkyl chlorides with the silicon copper alloy while the main
and sought-after product is dimethyldichlorosilane.
organosilicon compounds are also prepared in laboratory by many methods some of
which are given below
can be prepared by the reaction of silicon tetrachloride with organo-lithium
can be prepared by the reaction of trialkylsilylchloride with Grignard reagent
reduction reaction of dialkyldichlorosilane with lithium aluminium hydride
can be prepared by reaction of trichlorosilane with unsaturated compound such
as alkene etc…
BY HYDROSILYLATION METHOD:
direct process the second major method for the formation of Si-C bond is
hydrosilylation (hydrosilation ) . in
this process the hydrosilanes adds to the unsaturated substrates , mostly alkenes are used , Alkynes , imines , ketones , aldehydes , etc..
can also be used
example is the hydrosilation of phenylacetylene
requires metal catalyst especially those based on the platinum group metals.
compounds involve reactions which involve the cleavage of C-Si bond by nucleophilic
or electrophilic substitution reactions. The order of ease of C-Si bond fission
? ? ? ?
E+ Nu- E+ Nu-
(1) (2) (3) (4)
reactions involve in the type 1 of organosilicon reactions is as
rate of R3SiH-H exchange is
104 more as compared to the H-H exchange.
reaction is called as the Sakurai
reaction and is example of type 2
type of reaction takes place in the presence of a strong Lewis acid catalyst
and also slow fission takes place in the presence of cc-acid
type of reactions occur only in the presence of a strong nucleophile
C-Si fission can occur more readily if
leaving group is present in beta position
RELEASE OF RING STRAIN:
GOOD LEAVING GROUP IN
organosilicon compounds are more reactive than saturated organo-silicon
reactions are possible at carbon to carbon double bond and triple bond.
are useful intermediates in the synthetic chemistry.
bond can be readily cleaved
allyl and vinyl silanesareindespensible
nucleophiles in the organic synthesis and can be used in the host
structure of this compound is given as
is prepared as follows
Trimethylvinylsilane is thermally stable.
Si-Vinyl bond is generally resistant to cleavage by acids or alkalies. The
above reaction occurs at 200 degree celcius.
and epoxidation are possible without Si-C cleavage
ORGANOSILICON COMPOUNDS CONTAINING
compounds are the analogues of the alcohols and are mostly prepared as follows
HYDROLYSIS OF SILYL CHLORIDE
OXIDATION OF SILYL HYDRIDES
are deprotonated derivatives of silanols
tends to dehydrate to give siloxanes
have connectivity Si-O-C, they are typically prepared by the reaction of
alcohol with silyl chlorides
in protection in organic synthesis.
Some other organosilicon compounds
the compounds containing C=Si bond. The first evidence of silene was given by
Guselnikov and Flowers in 1967 from the pyrolysis of dimethylsilacyclobutane.
are silacyclopentadienes, are members of large class of compounds called
metalloles. They are silicon analogues of cyclopentadienes and are regarded
efficient in electron transport.
Saturated organosilicon compounds:
have been much studied in last 20 years or so. They are generally prepared by
reaction of dihalides with di-grignard reagents or di-lithium
organo-derivatives. These may also be performed or prepared in situ. Coupling
with alkali metal is also possible
is also possible to couple chlorosilanes and alkenes with lithium
Cyclic unsaturated organosilicon
can be preparedby coupling reactions between alkali metals, alkynes, and diorganochlorosilanes,
also by dehydrogenation of appropriately substituted silacycloalkanes. Direct
dehydrogenation of saturated cyclic organosilanes normally gives poor yield
can be made by ring closure of dibromo compounds, using reactive metals or by
mild dehydrogenation of halogen-substituted silacyclobutanes
are highly susceptible to cleavage by electrophilic reagents eg; HCLO4_MeOH,
Br or by nucleophilic reagents eg: RLi, ROH.
OF ORGANOSILICON COMPOUNDS
compounds have many applications some of which are as
compounds can be directly applied in the monomeric form eg: it can be made to
silicone polymer by hydrolysis and polymerization.
can be used as anti-adhesive materials.
can be applied to drug boosting hair growth and in anti-cancer drugs.
the field of organic synthesis, it is used as reducing as well as protective
agent of the active groups.
is used for the protection of the carbonyl groups as well can be used for the
protection of alcoholic groups
a kind of monomer it can be used as silylating agent as well as being used for
covering the surface of material.
also be used for the moisture protection of electrical insulating materials.
of organosilicon compounds.http://www.dowcorning.com(accessed
compounds introduction and applications. https://www.chemicalbook.com
of silicon and silicones.http://archive.boston.com/
(accessed Dec 19,2017).