You can form oxolate salt of amines but I guess its a little bit tricky,it might be good alternative to hcl,but if you have any left oxalate acid in your product,its toxic
The amine freebase was dissolved in 5x its volume of dry IPA, and added dropwise to 1eq of anhydrous oxalic acid dissolved in IPA. In some case, no solid formed directly. 3x the volume of ether as added, and teh erlenmeyer placed in the freezer. An hour later, a voluminous fluffy white precipitate had formed. It was vacuum filtered, offering a gel like solid. It was triturated under ether, and dried by suction, then under vacuum. Recovery was between 60 and 95%.
Evaporating the filtrate gives an oily material, which crisatllizes when covered with ether and placed in the freezer. Recrysatllization with IPA:ether removes the last traces of oxalic acid.
With this method you can also form citrates
Instead of ipa you can try using ethyl acetate