# How to correctly write the condensed formula for salicylic acid

I am struggling to find the right way to write the condensed formula for salicylic acid

Some people say CHCHCHCHC(OH)C(COOH) Or (CH)4C(OH)C(COOH)

Others say C6H4(OH)COOH (which doesn't seem to make sense since it looks to me like it could represent many isomers and not just one molecule like a condensed formula is supposed to)

Which (if any) is correct?

• A pretty straightforward way would be $\ce{(o-C6H4)(OH)(COOH)}$ and variations. (o-C6H4) suggests can't be interpreted in any other way then orto-disubstituted benzene ring. – permeakra Apr 23 '16 at 22:10

Some people say $\ce{CHCHCHCHC(OH)C(COOH)}$ Or $\ce{(CH)4C(OH)C(COOH)}$

Both of these are definitely wrong since it seems to indicate some sort of alkene.

Others say $\ce{C6H4(OH)COOH}$

This is much better since it "hints" that $\ce{C6H4}$ is a benzene ring. With only 4 hydrogens and what seems to be two substitution groups that fits. Note there is no indication of the relative position of the groups. So this would represent either 3-Hydroxybenzoic acid or 4-Hydroxybenzoic acid as well.

The basic empirical formula would be $\ce{C7H6O3}$ which would represent probably dozens of molecules.

So the best way to denote the particular molecule specifically is to name it, or to draw out the whole 2D structure.

• Maybe OP is trying to reinvent SMILES? – Mithoron Apr 23 '16 at 21:21
• simplified molecular-input line-entry system (SMILES) en.wikipedia.org/wiki/… – MaxW Apr 23 '16 at 21:37
• Thank you very much for your answer. I agree that drawing it out or naming it would be much better, however the assignment requires the condensed formula. So I guess I will use C6H4(OH)COOH then. – RaymondSWalters Apr 24 '16 at 6:07