A couple of synthesis methods for 5-bromovanilline can be found on Rh's site as well as on the Hive collective using TFSE. However, there is one method which isn't "stressed" in the texts but has proven to be rather valuable in my syntheses.
Rh's original page: https://www.thevespiary.org/rhodium/Rhodium/chemistry/mmda.mescaline.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/mmda.mescaline.html)
A 250 mL RB flask was charged with 5 g vanilline (32.9 mmol) and dissolved in 50 mL glacial HOAc. The mixture was stirred with a magnetic stirbar. When all vanilline was dissolved, 2 x 1 mL bromine (39.0 mmol) was added with a 5 min interval. After one hour, 150 mL cold (4°C) dH2O was added. The yellow-orange precipitate was filtered and the RB flask rinsed with another 50 mL cold dH2O, which was used to wash the precipitate as well. The precipitate was then washed with another 25 mL cold dH2O and dried to yield 7.5 g 5-bromovanilline (32.5 mmol) as a powder. Total yield: 98.7% Purity: 96% (via GC).
Voila, just to put the method into your attention. Pls be careful when handling bromine. It is a rather toxic substance...
Thanks, I've added it to the above document. How did your Eugenol experiments go?
I'm still waiting for my heating mantle, necessary for vacuum distillations :( . Aside that, it seems a nice alternative, but only if you're hardcore. There is a need for alot of solvent to purify the product, and the yields are low. On the other hand, the required chemicals are cheap and unwatched.