[carotis]

I would say no because it would be more probable that it reacts into a benzoylchloride but who knows? 
Although I know it takes something like SOCl2 to synthesize benzoylchloride wheras an attack of an aktivated Cl2 on the polyene system is a rather different mechanism. Hmm...
I've meant of course "to chlorinate", not to chlorine xD

[sjb]

So you mean going from e.g. to (or the meta / para regioisomer)?

[carotis]

yes, that's precisly what I've meant

[beardy]

What do you know about protecting groups? Perhaps carboxylic acid could be protected in order to carry forward the chlorination. What ways of protecting an acid are you familiar with?

[carotis]

The common protection groups for carbon acids would be esters

[SirReal]

I am a newer student, so I have a question.

Would reaction of HCl with benzoic acid dehydrate the hydroxyl group, or would it add to a double bond of the benzene ring in markovnikov fashion?

[kriggy]

None of those. You could probably get some decarboxylation by heating it together but I doubt that. You need to realize that hydroxyl in COOH group is quite different from OH in alcohols. Also, the double bonds in benzene ring are not quite doble bonds but the electrons are spread over the whole ring instead of being three separate double bonds

[SirReal]

 I see.  We have not even gotten to carbonyl or ester functional groups yet, nor have we learned anything about benzene rings.  Was just trying to apply my knowledge of ochem 1 to higher level concepts.