Help with harmala precipitate

[awalmartbag]

After a long hiatus, I decided to give Rue extraction another shot.

I did the standard vinegar cook, filtered, cleaned it up with some ACS-grade ethyl acetate (sloppily - I now realize I shook the funnel too much and created an emulsion...), and then basified with ~2M NaOH solution to a pH of ~12.

Orange crystals precipitated out of the brown/red solution as expected, which I then attempted to filter out. After ~24 hours, filtration had stalled, there was maybe 10-20mL of liquid left above the solid material, which was a dark brown sludge rather than the nicer crystals I had observed in solution.

I reasoned that most of the impurities would be contained in the ~1L that did filter through, so I swapped the flask attached to the filter, and attempted to dissolve the sludge with some water+vinegar solution, collecting the acidic filtrate, which hopefully contained the alkaloids.

About half of the solid material dissolved, and the filtrate collected was a light yellow color. I basified it again and collected the solids, now easily filtered and light beige/tan in color.

What is this brown sludge? The result of some condensation reaction induced by the presence of OH?

Are my alkaloids ok to use or do they require further cleanup?

Pics attached

 

[Transform]

Check out the harmala extraction thread and you'll see that lately there's much more of a consensus that filtering rue (other than the whole seeds) is a pain and best avoided wherever possible. Waiting patiently for solids to settle and then decanting off the liquid is more favoured. This can be done both before and after adding the base, with further acid/base cycles leading to more of the dark sludge settling out each time.

Performing a few water washes, maybe with a dash of ammonia, on the final freebase harmala precipitate should clean off any excess of non-volatile base that may have remained on the product.

 

[doubledog]

After first basification, some brown sludge along with harmalas precipitate and complicates any filtering. That's why you should acidify this precipitate again (as you did) and only after that filter it.
After second basification filtering while it's in basic form works fine.

 

[modern]

If you basify slowly increasing the ph and stopping before reaching 7ph it tends to precipitate the brown sludge impurity that doubledog mentioned.