But, according to this, phenol does react with Sodium Carbonate (and not sodium bicarbonate):

For bufotenine pKa1=9.23, pka2= 9.91

Therefore, the ideal pH is 9.57 to extract bufotenine with acetone. Above pH 9.9 we should start to lose yield.

What confuses me is that with sodium carbonate (pH ~11), we should be getting sodium bufotenate and no yield.

BUT, I think we don't have sodium carbonate alone. Yopo seeds have a lot of alkaloids. A significant ammount of sodium carbonate reacts with the natural salt of bufotenine to create sodium bicarbonate and "freebase" bufotenine. Other plant stuff (proteins, etc) also may react, increasing the buffering effect.

We therefore have a buffer.

I think it is the buffer system that makes this process work! Also, drying may help as excess sodium carbonate drops out of solution lowering the buffer pH.

One can play with the buffer calculator taking into account that 100g of seeds at 8% bufotenie salt will consume 4.1g of sodium carbonate when "freebasing" and generate 3.3g of sodium bicarbonate.

Ideal sodium carbonate considering the bufotenine salt conversion seems to be 6g. But there is other plant stuff so the ideal will be higher.

Overall, using too much sodium carbonate alone may risk some bufotenine not being neutral. Or maybe the natural buffer with all the other plant stuff is good enough if only sodium carbonate is added, especially when drying as not as much sodium carbonate can stay in solution and the smaller amount of sodium bicarbonate becomes more important (?).

Perhaps it is worth testing an extraction with leass sodium carbonate (~10g to 15g range per 100g of seeds). This may be especially true if we want to use a wet paste and ethyl acetate.