Making oxalic acid

[Beeforest]

Does anyone know if it's possible to make oxalic acid from rhubarb leaves that would be suitable to treat a colony of bees in the winter?

The problems I guess would be achieving the correct dose.

http://www.ehow.co.uk/how_6057023_extract-oxalic-acid-rhubarb.html

 

[Black Comb]

You can buy half a kilo of crystals from Big T for around a tenner. Will last you years. Don't see the point in messing around with rhubarb leaves.

 

[The Cumbrian]

Don't see the point in messing around with rhubarb leaves.

Interest and an inquiring mind perhaps?

 

[Beeforest]

Will last you years. Don't see the point in messing around with rhubarb leaves.

Can't see the point of messing around with bees, can buy some local honey from the farm shop!

EDIT Yes, it might be a faff but I grow a lot of rhubarb in my forest garden and am interested in self-sustaining systems.

 

[Bee-Key-Pur]

I guess you could, the question has been asked before and they also got shot down...

 

[enrico]

Try it and let us know!

 

[Hombre]

You will certainly have very clean pots, but given the cost of fuel for the reduction and the effects of the fumes as it becomes more concentrated suggests that it is probably better as a closed process.

Interestingly though how is it manufactured commercially? I have a feeling that like so many things, that it is a biproduct of another process - not necessarily cooking up unripe rhubarb.or it's leaves

 

[Finman]

.
DIY

Best Answer - Chosen by Asker
From Wikipedia:
"Although it can be readily purchased, oxalic acid can be prepared in the laboratory by oxidizing sucrose using nitric acid in the presence of a small amount of vanadium pentoxide as a catalyst.[1]
^ Practical Organic Chemistry by Julius B. Cohen, 1930 ed. preparation #42"

 

[Beeforest]

.
DIY

Best Answer - Chosen by Asker
From Wikipedia:
"Although it can be readily purchased, oxalic acid can be prepared in the laboratory by oxidizing sucrose using nitric acid in the presence of a small amount of vanadium pentoxide as a catalyst.[1]
^ Practical Organic Chemistry by Julius B. Cohen, 1930 ed. preparation #42"

No mention of rhubarb leaves then? Could be doing this
I would have to be confident that anything I was dribbling over the bees was at the right concentration. Hmmm...

 

[gavin]

There is the concentration issue, but I'll bite my tongue there.

Your main trouble with that recipe is that you are precipitating not oxalic acid but calcium oxalate. Goodness knows how you'd recover oxalic acid from that.

And if you were to try to extract without precipitating you'd have the worry of wondering what all that leaf juice would do to your bees.

 

[Beeforest]

There is the concentration issue, but I'll bite my tongue there.

Your main trouble with that recipe is that you are precipitating not oxalic acid but calcium oxalate. Goodness knows how you'd recover oxalic acid from that.

And if you were to try to extract without precipitating you'd have the worry of wondering what all that leaf juice would do to your bees.

So it looks like a non starter. Oh well!

I have some Thyme plants - Thymol again?
Thought so!!

 

[REDWOOD]

Can't find anything on rhubarb but an interesting page on garden pests that might help bees
http://www.longfordcoco.ie/coco_content.aspx?id=10032

 

[johnnythefridge]

Oxalic acid from rhubarb

maybe you dont need to manufacture oxalic acid in the pure form. Maybe the mites would hate raw rhubarb juice as much much as a preparation of oxalic acid ? Myself, I prefer to eat my raw rhubarb dipped in sugar rather than use it for a miticide, but perhaps it's worth a shot. Regards, John.

 

[Moggs]

Rhubarb and honey - just waiting for the custard. Anyway, a dear old allotment gent advised me to boil up some rhubarb leaves as a pesticide for the veg when he knew that I was avoiding the evil chemicals in proximity to the allotment bees. He wasn't at all surprised to learn that oxalic (as in rhubarb) is used for varroa.

So, next question. Can I dribble OA on my brassicas?