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Formula to calculate total no. of isomers of a compound

CyBorG

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9 Apr 2007 17:30:37 IST

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9 Apr 2007 17:30:37 IST

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Formula to calculate total no. of isomers of a compound

Chemistry , Inorganic Chemistry ,

DOUBLE BOND EQUIVALENTS or INDEX NUMBER:

It is a numerical value on the basis of which we can have an idea about the different type of equivalent structures we can have for a given formula.

Knowing the DBE the problems on structural isomerism can be more easily solved.

Mathematically,

DBE= {(

n(v-2))/2}+1

where n is the number of atoms

v is the valency of the atom.

Eg 1):

Consider C₄H₆

DBE={4(4-2)/2+6(1-2)/2}+1

={(8-6)/2}+1

This implies that the molecule may contain,

1)two double bonds or one triple bond.

2)one ring and one double bond.

3)two rings.

Thus by knowing the DBE total number of structural isomers can be formulated.

Eg 2):

Consider C₃H₆O

DBE={3(4-2)/2+6(1-2)/2+1(2-2)/2}+1

So the isomers may contain either a double bond or a ring.

I hope this is helpful!

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Comments (3)

vinu

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Joined: 15 Dec 2006 20:06:39 IST

Posts: 321

10 Apr 2007 16:45:07 IST

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Sure u bet , it IS helpful !

Prashanth G

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Joined: 18 Feb 2007 18:57:58 IST

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10 Apr 2007 16:56:30 IST

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it is indeed helpful..........

Umang

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Joined: 12 Dec 2006 21:48:31 IST

Posts: 926

30 May 2007 11:15:09 IST

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Hey adarsh !
i hav read about this method in books , but I find it really confusing !!!!!
Is there no other way ?????

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