study material-chemistry
Iromerism explained the easy way!!
here is a method to calculate the no. of optically active isomers , meso forms and racemic mixture ina a given compound…..
here
a - optically active isomer
m - meso form
r - racemic mixture…
okay in case 1
when there are n chiral carbon atoms bt there is no plane of symmetry
then ,
a = 2n
m = zero
r = "a"/2
take n = 1,2,3,4,5,6,7……………………….
case 2
when compounds have n chiral carbon atoms , and plane of symmetry is possible…..
then it further have 2 cases
- IF N IS EVEN
 a = 2n-1
r = a/2
m = 2(n/2) - 1……….(whole is in power okay?>???)
- IF N IS ODD
a = 2n-1 - 2(n-1)/2
r = a/2 (always….)
m = 2(n-1)/2……..(whole in power again)
so by these ways , u can calculate no. of optically active isomers , meso forms n racemic mixture…
and 1 more thing….
how to calculate optical isomers…..
in simple compounds…..
1st check the chiral carbon…..
if its nt present , den its optically inactive
if its present
then
a) If 1 chiral carbon atom , the compound is 100% optically active…..
b)If more dan 1 chiral carbon atom ,
den check plane of symmetry
i)If plane of symmetry present , compound is optically inactive
ii) If plane of symmetry absent , compound is optically active…..
OPTICALLY ACTIVE COMPOUNDS , WICH ARE MIRROR IMAGES OF EACH OTHER ARE ENANTIOMERS….(AND ENANTIOMERS ALWAYS EXIST IN PAIRS)
and the configurational isomers wich arent the mirror images of each other are called diastereomers
racemic mixture - equimolar mixture of 2 enantiomers (as i have already said dat dey exist in pairs) is called racemic mixture…
seperation of racemic mixture into individual components is called RESOLUTION…..
NOW THIS IS IMPORTANT TOO……
- If in a ficher projection we do odd no. of exchanges around all Chiral carbons , we get an enantiomer
2)If in a ficher projection , we do even no. of changes around all chiral carbon atoms , we get the same molecule….
3)If in a ficher projection , we do odd no. of exchanges on some chiral carbons n even on other , we get diastereomers…..