[atom145]

For my Advanced Higher Chemistry project (a piece of coursework in the last year of school) I'm trying to determine experimentally the identity of an unknown organic compound chosen by my teacher. It's a white odourless crystal.

It decolourises bromine so it's unsaturated (I know some saturated compounds may react with bromine but it will only require Chemistry that I've been taught). It doesn't contain a halogen or sulfur for the same reason. It burns with a smoky flame and is insoluble in water and HCl but dissolves in NaOH and forms bubbles (I haven't had time to set up lime water to check it's CO2) on addition to NaHCO3 so it's acidic.

It melts at approximately 132 degrees C.
I can't think of any compounds which fit the bill. I considered fumaric or maleic acid but my teacher made it clear that's wrong. He's also suggested there's a benzene ring, which fits with the smoky flame.
Any ideas??

[Babcock_Hall]

Try drawing out a substituted benzene ring, where the substitution has the chemical properties that you observed.

[atom145]

It's bound to be a common compound though. A phenyl propenoic or larger acid is the only option I can see that works, and I can't find any such compound online.

[Babcock_Hall]

Several such compounds exist.  Try replacing one hydrogen atom on benzene with a carboxylic acid group, just as a starting point.

[atom145]

From a drawing out of the molecule, would carboxystyrene be a reasonable possibility?

[AWK]

Do you mean cinnamic acid?

[atom145]

I meant this, although it would mean I'd got the wrong boiling point:
http://www.chemspider.com/Chemical-Structure.13476.html?rid=37e8ce9f-f6a7-42a4-ad51-358193714149&page_num=0
but obviously it is cinnamic acid, which has the right boiling point and appearance.
Thank you!

[billnotgatez]

@atom145

I assume you mean melting point not boiling point

[atom145]

Oops, yes I did. Slip of the keyboard.