[sophotect]

I am thinking of distilling some furfural for use as organic polymer using a setup akin to this one: http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0280
I will preface all this with: I am doing this on a budget. I have access to all the reactants & apparatus mentioned in the article save for vacuum & chloroform. Since I want the product to polymerize, I am less concerned with initial vacuum distillation but eliminating as much water as possible is a concern.

Apparently furfural can be distilled from corn cob, wood (presumably, paper as well) & mineral acid but before I set it up, it occurred to me that it might also be done more cheaply, efficiently if I start with xylitol from ye olde health food store. Fewer side products, easier cleanup, hopefully. I'm going to do at least one run using xylitol, and others using either corn cob or sawdust or paper.

Wikipedia says furfural is slightly soluble in water - 83g/L - I am starting with a few hundred mL at most & a significant portion is going to remain in water! My question is related to collecting & separating the furfural oil from the water in the receiving flask. I don't have ready access to chloroform, though I suppose I could make some. Does anyone have ideas on maximizing yield and ease of recovery without chloroform?

I was thinking maybe fractional freezing of the distillate and / or starting with less water but additional suggestions are welcome.

[billnotgatez]

While waiting for us to ponder you question I want to point out WIKI also says

Although it occurs in many foods and flavorants, furfural is toxic with an LD₅₀ of 65 mg/kg (oral, rat).[7] It is a skin irritant and chronic skin exposure can lead to a skin allergy as well as an unusual susceptibility to sunburn.

If it is not a secret, it would be interesting to know your goal.
Also , since it is available comercially, why not buy furfural.
Or are you doing this as a practice experiment.
 

[Arkcon]

When I was a kid, furfural and other furans steam distilled from agricultural waste were going to take the world over, and were hot topics.  This would have been in the 1970's when the US was severely gripped in a petroleum embargo.  If the benefit was going to be realized, I would think that it would have by now.  Maybe you should by furfural at first, to see your production feasibility.  Failing that, you may want to fractionally distill your crude product, and try to find out what each fraction is, and see how to integrate it into the polymer synthesis you want to take with it.

[sophotect]

My wife makes soap at home. Lately, she has been using my equipment more than I have (bragging? complaining? you decide!) so this is something to blow the cobwebs out.

It is no secret, I want to see if usable polymers can be made with biomass. Not just in the sense yeah, DOW does it all the time, but can I do it with cheap, readily available materials one can buy at hardware store or even grocery store. I also plan on tinkering with starch plastics, but furfural seems more promising in part because it appears to take less work. As of this writing.

I did see the warning about its toxicity; I don't plan on ingesting, inhaling or slathering furfural all over my body. Most likely, I will use it as a thermosetting resin and/or mold binder.

@Arkcon: I do see brokers offering quotes on furfural, nothing in local shops or eBay. My experience has been, if I need to ask a broker, I can't afford their minimums, let alone shipping. I've been wondering what furfural's practical limitations are myself. They must be significant if the applications have been known that long, however, that just fuels the fire of curiosity.

EDIT: Minimum order: 1 metric ton
HAHAHAHA
China uses a LOT of furfural so maybe they know something we don't.

[SteinerPDP]

@sophotec: Furfural is an industrial chemical and I would not recommend you make it at home or in a non-laboratory environment .. labs usually have vacuum . Steam distilling means effluent and that needs correct treatment. Furthermore, the lignocellulosic residue would have to be disposed-off, also. It is acidic (besides furfural, you'll also make e.g. acetic acid). Furfural is also a very strong solvent and highly reactive when catalysed (it is still used as a component of the rocket fuel used by the Ariane)!. Suggest you study its chemistry and its uses. This map may give you an idea.

Thermoset resins or binders: They are NOT made from furfural, but from Furfuryl Alcohol (FA). You'll see on that map that furfural is simply the platform for some very interesting (and some very toxic!!) chemistry. This video clip will give you an indication of what you can do with FA chemistry.

@Arkon: There are many good reasons why furfural did not take-over the world (See historic background). Oil based products were (are?) cheaper and nobody wants to pay extra for e.g. Lycra or Nylon that is made from bio-renewable chemicals. The current trends in oil-prices have changed the game and we see that there are some great new applications for furfural.

[Ander08]

    Although I agree this shouldnt be done in a non-laboratory environment, If you wanted to separate furfural from whatever water is remaining, i would use a seperatory funnel, and also apply a drying agent such as silica dioxide. once you filter out the silica you should have a somewhat pure yield.

[sophotect]

Thanks for the replies, all. I am going to wait a bit longer until I am better equipped such as having a vacuum pump & better solvent selection before proceeding.

[Wastrel]

I think using Xylitol would be tricky, it's not the same as Xylose.

I'm surprised Furfural is so toxic, it's not something I've seen highlighted in the textbooks.

[SteinerPDP]

@Wastrel: Xylose: correct. Have a look at the reason: dalinyebo.com/furfural#how-is-it-made. Toxicity: 5l of carrot juice will kill you .. and you will not find that in the text books, either! Furfural is an industrial chemical and has to be handled accordingly (see MSDS: dalinyebo.com/bio-renewable-chemicals/furfural-msds-for-ecoral™). Furfural is also a food flavour and a vitamin C degradation product found in you body, too! It (and its derivatives) give flavour to coffee, wine, bee, cider, whisky, etc. (dalinyebo.com/item/645-furfural-derivatives-in-apple-cider-and-wine).

@sophotect, @Ander08: furfural forms an azeotrop, so use azeotropic distillation to separate. You can use solvent extraction, but again, that does not belong in a non-laboratory environment.

[Ander08]

So youre saying furfural is miscible in water? because if it is then the seperatory funnel would be of no use. But would the use of a drying agent work?

[SteinerPDP]

Yes it is, as a function of temp. See attached. Drying agent: we're talking about water removal, not a few% moisture, so I don't think that would be viable.