isomers?

[ChemSiddiqui]

hi, can any 1 tell me whether from a formula of an organic compound , can we deduce how many isomers will that compound have? if so how?

 

 

any help will be most appreciated.

[woelen]

Yes, that is possible. There are some basic rules:

 

C-atoms have 4 bonds

O-atoms have two bonds

H-atoms always have 1 bond

N-atoms have 3 bonds

 

There may be double bonds between atoms.

 

An example:

 

C4H10O

 

This can be

CH3CH2CH2CH2OH

CH3CH2CH2OCH3

CH3CH2OCH2CH3

(CH3)3COH

CH3CH(OCH3)CH3

CH3CH2CH(OH)CH3

 

All isomers can be listed systematically. One has to be careful not to forget one, and one also easily mentions doubles.

 

It is not always true that all isomers, which can be constructed, using the enumeration of all possible arrangements, also exist in reality. Some structures require spatial arrangements of atoms, such that atoms would overlap in space. Of course, that is not possible and such isomers do not exist in reality.

 

Altogether, given just a formula, in general, it is not easy at all to determine all possible isomers, which also could exist in real life.

[YT2095]

think of it like ball/stick models, you`re given X amount of pieces of each atom, how many things and shapes can you construct out of it?

 

there will be the occasion when 2 balls want to occupy the same space, this cannot happen in reality, and so the model is invalid.

 

it`s just like playing with LEGO as a kid really

[woelen]

YT, really this is one of the best explanations I have seen . It perfectly explains the problem in a nutshell.