Q. Write a structural formula for each of the following compounds:
Ans.
(a)
N,N-diethylanminocyclopentane
The principal or parent chain is cyclopentane
N,N - diethylamino
refers to a 30 amine which are named as N-alkyl
-N-alkylaminoalkane or N,N- dialkylaminoalkane in case
two substituent alkyl groups are the same.
thus, the chain is
the structural formula of N, N - diethylamino
cyclopentane is
(b) ethylpropylamine
Secondary amines
are named either as alkylalkylamine (common name) or as
N-alrylalranamine.
Thus it is a secondary amine having structure-
CH3 CH2 -NH-CH2 CH2
CH3
(c)
tetramethylammonium hydroxide
The given compound is a quaternary ammonium compound.
These are regarded as derivatives of ammonium salts in
which all the four H-atoms of ammonium ion (NH4+)
are replaced by alkyl or aryl groups. Here alkyl group is
methyl (-CH3) Thus, replacing all four
hydrogens of NH4+ OH by -CH3
we get the structure of tetramethyl ammonium hydroxide.
[(CH3)4N]+OH-
(d)
1,3-diaminobutane
Here the parent chain is butane with amino (-NH2)
group at position 1 and 3.
Q. Write a correct name for each of the following compounds:
Ans.
(a) H2N(CH2)3
NH2 = H2N-CH2 -CH2 -CH2-
NH2
Aliphatic amines are called aminoalkanes. The
complete name is given as follows:
(i) Parent alkane corresponding to straigtht chain is -CH2 -CH2 -CH2- then the name propane.
(ii) The position
of amino groups are indicated by arabic numerals with
carbon atom bearing the amino group getting the lowest
possible number.
therefore- the
name is 1,3 -diaminopropane
(b)
This is a quaternary ammonium salt which is named as
tetraalkylammonium followed by name of the ion. The
alkyle group here is butyl, thus the name is
tetrabutylammonium hydroxide.
(c)
- NHCH2
CH3
This is an aromatic secondary amine. In this the
parent name is benzenamine for
and since ethyl group is attached to N, it
is named as 'N-ethyl'.
therefore- the complete name would be N -
ethylbenzenamine
(d)
It is a 30 amine which are named as
N-alkyl -alkylaminoalkane
The largest alkyl group forms a part of amino alkane
while smaller alkyl groups are considered substituents.
The larger alkyl group here is cyclohexane and smallest
alkyl groups are dialkyl (dimethyl)
therefore- name is N.N-dimethylaminocyclohexane.
Q. Draw the structures for and name and classify as primary, secondary, or tertiary all the isomeric amines with the molecular formula C5H13N.
Ans.
Amines show 4 types
of isomerism:
(a) Chain Isomerism - Using this we get
following three structures for C5H13N.
pentan - 1-
amine (10 amine)
- 3- methylbutan-1-amine (10 amine)
2, 2 -dimethylropan-1- amine (10 amine)
(b) Position
Isomerism: - This is due to difference in position of
the amino group.
pentan - 2- amine (10 amine)
pentan - 3- amine (10 amine)
3- methyl butan-2-amine (10 amine)
(c) Metamerism - Which have same molecular formula but different alkyl groups in either side of the nitrogen atom.
H3C - CH2-NH-CH2
CH2 CH3 N-ethylpropanamine (20 amine)
H3C -NH-CH2 CH2 CH2
CH3 N-methyl butonamine (20 amine)
2-methyl-1-(N-methylamino) propane (20 amine)
2- metyl -2-(N-methylamino) propane (20 amine)
(d) Functional isomerism - 10 20 30 amines having same molecular formula show functional isomerism among themselves. The 10 and 20 amines have already been covered albove, so the possible 30 amines with molecular formula C5H13N are -
N- methyl-N,N-diethyamine (30 amine)
N,N-dimethylaminopropane (30 -amine)
Q. Write the formula for each of the following in its dipolar ion form.
Ans
(a) Leucine
(b) Threonine
(c) Methionine
(d) tyrosine