IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

samuelrancho

i want to know how to find how many isomers a compound would form?a general way of getting the no of isomers(structural).and also what is tautomerism and different type of tautomerism and their different aspects

pirate1_from_jee

Tautomerism:

pirate1_from_jee

Tautomers are organic compounds that are interconvertible by a chemical reaction called tautomerization.The concept of tautomers that are interconvertible by tautomerizations is called tautomerism. Tautomerism is a special case of structural isomerism .

pirate1_from_jee

1) if the molecule is unsymetrcl

no.of enantiomeric frms(x)=2ⁿ

no.of meso forms(y)=0

total no. f stereoisomers=x+y

2) if the molecule is symetrcl & n is evn

no.of enantiomeric frms(x)=2^(n-1)

no.of meso forms(y)= 2^(n/2)-1

total no. f stereoisomers=x+y

3) if the molecule is symetrcl & n is odd

no.of enantiomeric frms(x)=2^(n-1)-2^(n-1/2)

no.of meso forms(y)= 2^(n-1/2)

total no. f stereoisomers=x+y

But if u wnt structural isomers, then u wl hve 2 do it by trial & error method.

utkarshsinha

To find the number of structural isomers do the following:

1) First create the straight chain isomer
2) Then branch out one methyl group in as many ways as possible
3) Then branchout two
4) ... go on...

just make sure you don't repeat any structure

pirate1_from_jee

Sorry yaar i 4gt it ws structural isomers, ya, utkarsh is right.

magiclko

tautomerism usually refers to the existence of two or more chemical compounds that are capable of facile interconversion, in many cases merely exchanging a hydrogen atom between two other atoms, to either of which it forms a covalent bond.... in organic chemistry, usually keto-enol tautomerism is mostly observed...

The interconversion of the two forms involves the movement of a proton and the shifting of bonding electrons..... A compound containing a carbonyl group (C=O) is normally in equilibrium with an enol tautomer, which contains a pair of doubly bonded carbon atoms adjacent to a hydroxyl (?OH) group, C=C-OH. The keto form predominates at equilibrium for most ketones... except phenol, which exists in 100% enol form

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