Regarding some decarboxylation attempts on “monomeric benzoic acid systems”.
Nicotine is a weak base with a pKa of 8.0 (from a very comprehensive paper on Nicotine - recommended).
2-Methoxy Benzoic Acid (same as Salicyclic Acid - but with a Methoxy, rather than a Hydroxy, group):
In the three experiments with this substrate, decarboxylation was almost complete, ranging from 84 to 88%. No starting acid was recovered …
The decarboxylation of 2-Hydroxy Benzoic Acid (Salicyclic Acid) was not attempted in study quoted above.