[Chemistry] Effects of iron (III), and iodine on esters

[Sean1218]

More specifically, on acetylsalicylic acid (both crude/made in class, and commercial/store-bought), and salicylic acid. Please hang with me, I'll get to my question in a second.

I did these tests:

Crude aspirin w/ iron (III): Translucent, light peach in colour
Crude aspirin w/ iodine: Cloudy, orange in colour

Commercial aspirin w/ iron (III): Cloudy, violet in colour; no change after adding a few drops of NaOH
Commercial aspirin w/ iodine: Opaque, dark, olive green in colour [this one should be dark purpley, so something went wrong]

Salicylic acid w/ iron (III): Opaque, dark purple in colour

Basically, I have to determine why I got the results I did (i.e. colour changes). Mainly why the commercial aspirin w/ iodine turned olive green, but crude aspirin was orange (since they contain starch it should be dark purpley, so what could have happened?), and why the salicylic acid w/ iron (III) turned dark purple.

Explanations for the crude/commercial aspirin with iron, and why adding NaOH didn't have any effect with the commercial would also be helpful if you know, but I mainly just need the other ones.

I did a bit of research for other tests that I ran (not listed) and managed to answer those, but these are the ones that I haven't been able to find much on.

So, any help would be great!

 

[Borek]

One thing that immediately jumps to mind is that commercial aspirin may contain many things, depending on brand - are you sure it is just starch that is added? Perhaps what you had was aspirin with ascorbic acid?

 

[Sean1218]

Well, I don't know starch was added, but my teacher said it should be dark purple, so I assumed.

 

[Sean1218]

Ok, I managed to answer most of them. All except for the iodine tests. I have no idea why it turned out the way it did. Anyone care to explain?