Posted by David Sharpe on Feb 15, 2013 7:01 pm
Hi James,
I'm afraid that what you are asking is not actually possible. There isn't a canonical/absolute way of numbering a chemical. That is to say, atom numbering is not a property of the molecule, it is an attribute of the nomeclature system and how it is applied. Take for example: http://www.chemspider.com/Chemical-Structure.13835772.html.
Here, the name 2-Methylphenol uses the position of the (phenolic) hydroxy group as the intial reference point (i.e. carbon 1) so the methyl group is in the 2-position.
But in the name 2-hydroxytoluene, the numbering is based on the methyl group being the point of reference (i.e. carbon 1) and the hydroxy group is in the 2 position.
It is for this reason that in a ChemSpider record we make the chemical structure the basis for the record and then link data and names to that.
If you have any further questions relating to this or any other aspect of ChemSpider, please do get in touch again - either in these forums or by emailing the ChemSpider team directly (chemspider-at-rsc-dot-org).
Kind regards,
Dave