{ stereoisomers
Isomer :compounds have the same structural formula but
Different in spatial configuration are known stereoisomers
The number of possible isomer of compound depends upon
The number of asymmetrical carbon atom
 Chiral center.

Asymmetric carbon - 4 different things are attached to it.

Cl
|
I =2n

I- C - F

|

Br
 You must have at least one asymmetric carbon to have stereoisomers.
EXAMPLE
glyceraldehyde
CHO
CHO
HO
H
H
OH
C
C
CH2OH
CH2OH
CHO
CHO
HO
H
CH2OH
L-glyceraldehyde
H
OH
CH2OH
D- glyceraldehyde
Types of isomer in glucose
1- D
and
L form
Pairs of stereoisomers

Designated by D- or L- at the start of the name.


They are mirror images that can’t be overlapped.
If you don’t believe it,
give it a try!
2-  and  forms (anomer )
The -OH group that forms can be above or below the ring resulting in
two forms -
anomers
Mutarotation : change in specific rotation of optically active solution
without any change in other properties
3- Epimer
What is an Epimer?
a. In a compound with more than one chiral carbon, only one of
the carbons differ in the epimer from the original
1. C #2 Epimer
2. C #3 Epimer
3. C #4 Epimer
EXAMPLE
4- Pyranose and furanose ring structure
furanose : is a collective term for carbohydrates that have a chemical
structure that includes a five-membered ring system consisting of four
carbon atoms and one oxygen atom. The name derives from its
similarity to the oxygen heterocycle furan, but the furanose ring does
not have double bonds.
Pyranose : any cyclic hemiacetal form of monosaccharide having a
six-membered ring
5- optical activity
Dextrorotatory :compound that rotate the light to the right is
Called dextrorotatory (d or +)
Levorotatory :compound that rotate the light to the left is
Called dextrorotatory (L or - )
Racemic :no optical activity (when equal amount of dextrorotatory
and levorotatory are present )
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