Introduction
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Figure 1: Alkyl halide is a derivative of Alkane |
1.
Primary
Alkyl Halides:
If
the halogen atom bonded to a carbon which is bonded to only hydrogen atoms or
only one carbon then the alkyl halide is known as primary alkyl halide. For
example, chloroform and ethyl bromide are called as primary alkyl halides.
2.
Secondary
alkyl halides:
In
this type of alkyl halides the halogen atom is bonded to the carbon atom which
is bonded to two carbon atoms. For example, isopropyl iodide has iodine
attached carbon which is bonded to two more carbon atoms therefore it is called
as secondary alkyl halide.
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Figure 3: Secondary alkyl halide |
3. Tertiary alkyl halides:
If the halogen atom is bonded to the
carbon atom which is bonded to three carbon atoms then that alkyl halide is
called as tertiary alkyl halide. For example, tertiary butyl bromide has carbon
atom which is bonded to three carbon atoms therefore it is known as tertiary
alkyl halide.
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Figure 4: Tertiary alkyl halide |
Common Names of Alkyl Halides
Common
names of alkyl halides are formed by naming alkyl groups followed by the word
“halide”. The common names are used only for simple molecules.
Compound |
Alkyl Group |
Halide |
Common Name |
|
methyl |
bromide |
Methyl bromide |
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ethyl |
bromide |
Ethyl bromide |
|
isopropyl |
fluoride |
Isopropyl
fluoride |
|
tert-butyl |
iodide |
tert-butyl
iodide |
|
cyclohexyl |
chloride |
Cyclohexyl
chloride |
|
cyclopentyl |
bromide |
Cyclopentyl bromide |
IUPAC Names of Alkyl Halides
According
to IUPAC naming system, alkyl halides are considered as halogen derivatives of
alkanes. Therefore the alkyl halides are named as “halo alkanes” along with the
carbon number to which halogen atom is bonded. For example, ethyl bromide is
named as “bromoethane” because two carbon atoms alkane is ethane.
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Figure 5: Ethyl bromide |
Let’s
see another example; n-propyl chloride has the halogen atom bonded to carbon
number 1 and three carbons alkane is known as propane, therefore IUPAC name of
the compound is “1-chloropropane”. Similarly isopropyl chloride has chlorine
atom at carbon number 2 therefore it is named as “2-chloropropane”.
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Figure 6: IUPAC names of chloropropane |
Consider the following example where bromide atom is bonded to cyclohexyl ring. In cyclic molecules numbering must be given from the carbon to which halogen atom is bonded. Therefore, name of the following compound is “1-bromocyclohexane”.
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Figure 8: IUPAC name of cyclohexyl bromide |
Let’s
see the following example,
To
assign name for the compound, first select longest carbon chain. Here the given
molecule has seven carbon atoms chain. Therefore root name of the compound is
“heptane”. The numbering for the carbons should be given from the end which is
closest to a branch. In this molecule fluorine atom bonded to carbon number 2,
and chlorine atom bonded to carbon number 3. Also there is “methyl” group is at
carbon number 5. Write the substituents in alphabetical order along with carbon
number. Therefore name of the compound is “3-chloro-2-fluro-5-methylheptane”.
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Figure 9: IUPAC name of branched alkyl halide |
Consider
the cyclic compound shown below; the given compound has six member cyclic ring
so the root name of the compound is “cyclohexane”. Now give numbering to the
carbon atoms starting from more branched side. So in the molecule ethyl group present
at carbon number 1, chlorine atom at carbon number 2 and bromine atom at carbon
number 4. Now arrange the substituents in alphabetical order. Therefore name of
the compound is “4-bromo-2-chloro-1-ethylcyclohexane”.
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Figure 10: IUPAC name of cyclic alkyl halide |
That's all for this topic. If you have any questions please feel free to ask me in the comment box. Thank you..!
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