I just checked my files and don't have a copy of the purchase and manumission, but you are correct that Alexandre was purchased by Martin and freed on the same day, from Livaudais.
I mailed the copy I had to someone in the Donato family.
There is note in my file that the transaction took place in 1826, and Alexandre is above the age of 30. It is also mentioned that he is about 60 years old.