[Aznhmonglor]

This is the problem that I am stuck on, I know that the acid derivative is an anhydride. I've drawn the structure and got it correct, now I dont know what the "other reactant" is. I tried water but it wasn't correct, took a guess because I know that water turns an anhydride into 2 carboyxlic acids. Any suggesting on what other reagent to use to get those two end products?

[azmanam]

which anhydride did you use?  what elements/molecular fragments are missing from the SM that are present in the product?  That is, if water were reactant B, you'd see the elements of water added to the product - 1 oxygen atom and 2 hydrogen atoms.  The elements of what are added to A?

[Aznhmonglor]

That is the anhydride I use. So I see that a OCH3 was added to one and OH to another? But what reactant would do that?

[azmanam]

OCH3 was added to one and OH to another?

no... count the elements again.

[Aznhmonglor]

Just a methanol to one because the oxygen that was already present become the alcohol on the other one?!

[azmanam]

Just a methanol

this part's correct.  I don't quite follow the rest.  Maybe draw the whole reaction scheme again with what you have now?

[Aznhmonglor]

So the other reactant would just be methanol right?

[azmanam]

yup

[Aznhmonglor]

Thanks Azmanam!