# Doubt from isomerism

No of stereoisomers for
2,3,5,6 tetra chloro heptane

Is it 6 ??

No,ans is 10

Apply formula

Of symmetrical case

Only general approach, no formula

Use RS.

2 identical meso from 2R and 2 nirror image from 3R 2 mirror image from 3S group which will be eleiminated so 16-6.See our notes for isomerism

3 Likes

Here total no. of stereoisomers =geometrical isomers +optically active isomers
Geometrical isomers=0
Optically active iosomers= 2^{n-1}+2^{\frac{n}{2}-1}
n=4

Ty for the formula bro...

Total stereoisomers = total optically active + total meso-form...
Total optically active = 2^(n) -1
Total meso-form = 2^((n/2)-1)
Is this formula wrong???

Our sir told to not use formula as far as i remeber there are 2 cases for n=odd and n=even this is true for even. But for odd there is other formula

For odd total no. of optically active
Stereoisomers
2^{n-1}-2^{\frac{n-1}{2}}

Bro without formula you cannot do cases with 5-6 or more stereogenic centers and even if you do it will take too much time then what's the point in doing that way