[lemonhead]

Hi everyone,

I have a question about naming organic molecules. When we name substituents in a molecule, we must specify both the carbon number on which each appears AND add a prefix (di, tri, tetra, etc) on the substituent name. A basic example would be 2, 4 - dimehtylhexane.

My question is: When would the addition of the prefix give you any *additional* information about the molecule's structure? It seems that by including the carbon number on which the substituent appear, there is already enough information. Are the prefixes just a naming convention that doesn't convey extra information, or are there cases in which these prefixes will be useful? If so, when/how?

Thanks!

Lemonhead

[P]

I think the dimethylhexane gives you the molecule - the 2,4 is the specific information.  It would just sound a bit wrong to me to say 2,4-methyl hexane, because methylhexane by definition is just hexane with a methyl group on it, not 2. So I suppose it doesn't give any extra information other than to give you the correct name, with the numbers giving position.