Question

Are these sentences grammatically correct?

Voy a las comprar.

Juan va a darlos.

Answer 1

The first one is correct because it's "I'm going to buy them." In Spanish; and the second one is not grammatically correct because it says "Juan is going to give them." In Spanish.
I hope this helps. =^D

Answer 2

The first one is: Voy a comprarlos (I'm going to buy them)
I'm going to=Voy
Buy them=Comprarlos (because is in plural)

The second one is correct
But it sounds better
"Juan va a entregarlos" or "Juan va a repartirlos"
Is up to you which one you want to use.

-Spanish speaker (my 1st language)