[oesan1]

The question is

Provide a mechanism for the first nucleophilic attack of vanillin on oxalyl chloride and stop at the formation of the first ester.


But where do you attack first? Is it alcohol on chloride first? How do you begin?

[Babcock_Hall]

Why don't you draw and post what you think is correct?

[oesan1]

Of course! I tried attacking from the ketone instead of the alcohol.

[rolnor]

Here is the structure of vanillin, its an aldehyde, not a ketone. You have a hydroxy group on vanilline, maybe it is important?


https://sv.wikipedia.org/wiki/Vanillin

[oesan1]

Yeah, I realized that, forgot to add the hydrogen. Wouldn't the only difference be a balanced oxygen group (the one near the ester)?

[Babcock_Hall]

Acid chlorides are quite reactive.

[oesan1]

So what would the chlorine atoms do if they are reactive?

[rolnor]

If you react an alcohol with an acid chloride, what do you get? You can google "ester formation"

[oesan1]

Ohhh, so if I attack the alcohol first, I'd get the chloride sooner!

[oesan1]

NOT THE CHLORIDE (the ester)

[rolnor]

Alcoholysis of acid chlorides, here;

https://en.wikipedia.org/wiki/Ester

[Babcock_Hall]

@OP, I think you are on getting onto the right track now, but it would not hurt to ask yourself, "Is chloride a good leaving group?"

[oesan1]

I think it would be, maybe in HCl form?

[Babcock_Hall]

Chloride ion is a very weak base, and weak bases make good leaving groups.  Therefore, a chlorine atom does not need to be protonated in order to leave.  Strong bases, by contrast make poor leaving groups, but they can sometimes be protonated to become good leaving groups.  The second point is tangential to the problem at hand, but it might be useful to you as you work on other chemistry problems.