Stereochemistry Assignment

Question 1

Draw the structures of the followings and state the types of structural isomerism and give reasons.
(1) propene and cyclo propane

Answer 1

(1) propene and cyclo propane
formula in gallery(1)
They are functional group isomerism because they have the same molecular formula but different functional group.

Question 2

Draw the structures of the followings and state the types of structural isomerism and give reasons.
(2) n-propyl alcohol and isopropyl alcohol

Answer 2

formula in gallery(2)
They are positional isomerism because they have the same molecular formula with the same carbon skeleton but differ in the position of the functional group on the carbon chain.

Question 3

Draw the structures of the followings and state the types of structural isomerism and give reasons.
(3) 2-methyl butane and 2,2-dimethyl propane

Answer 3

They are chain isomerism because they have the same molecular formula with differ in the arrangement of carbon atoms.

Question 4

Epimers

Answer 4

Isomers which differ only in the configuration at one of the several possible optical centre are known as epimers.
D(+)allose and D(+)glucose.

Question 5

Meso structure

Answer 5

If a point or plane of symmetry exists in a molecule, it is an optically inactive form and therefore identical with its mirror image and this compound is known as meso compound. They are optically inactive by internal compensation.
2,3 dichloro butane

Question 6

Enantiomers

Answer 6

Molecules that are non-superimposable mirror images of each other are called enantiomers. The two enantiomers rotate the polarized light in the same extent but in different directions.
D(+) glyceraldehyde L(-) glyceraldehyde

Question 7

What are requirements for optical isomers?

Answer 7

Those compounds which have one or more chiral centre(asymmetric) carbon atom and rotate the polarized light are known as optically active compounds.

Question 8

Requirements for geometrical isomers

Answer 8

(1) The compound must have double bond or ring system.
(2) The two groups attached to each double bonded carbon atom must be different.

Question 9

Does acrylic acid show geometrical isomerism or not? Give reason.

Answer 9

No, there is no geometrical isomerism because the two atoms of the same kind(hydrogen) attached to one carbon atom at the double bond.

H H
\ /
C
||
C
/ \
H COOH

Arcylic acid

Question 10

Define geometrical isomerism and compare physical properties of maleric acid anf fumaric acid.

Answer 10

Isomerism which results from restricted rotation because of either a double bond or ring system involving difference in arrangement of the atoms in space is called geometrical isomerism.
Physical properties of maleric acid and fumaric acid

H COOH H COOH
\/ \/
C C
|| ||
C C
/\ /\
H COOH HOOC H
maleric acid fumaric acid

(1) less stable 130
(2)low melting point
(3)high dipole moment
(4)high solubility in water

Question 11

Draw the structure of C2 and C3 epimers of glucose?

Answer 11

Gallery