Q. Write a structural formula for each of the following compounds:


(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-

(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.

(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:


(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

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.


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


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.


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 (2
0 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.


(a) Leucine

(b) Threonine

(c) Methionine

(d) tyrosine