| Pages:
1
2
3
4 |
garage chemist
chemical wizard
Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline
Mood: No Mood
|
|
Great Synthesis! Thanks a lot.
Why do they use H2SO4 and salt? It seems like HCl can be used, too (this is easier and cheaper). Or is the H2SO4 also important to the process? They
said that the HCl was the important factor.
|
|
|
Marvin
National Hazard
Posts: 995
Registered: 13-10-2002
Member Is Offline
Mood: No Mood
|
|
Difficult to say, but it is unwise to modify a tried and tested method.
For the oxidation, if you follow the links from the page jimwig pointed to, you'll find a method using oxygen catalysed by copper oxide/silver
oxide under the heading 2-furoic acid, only a small amount of silver nitrate is needed and the yeild looks high. There is also a description of the
prep of furan from this.
[Edited on 23-11-2004 by Marvin]
|
|
|
Theoretic
National Hazard
Posts: 776
Registered: 17-6-2003
Location: London, the Land of Sun, Summer and Snow
Member Is Offline
Mood: eating the souls of dust mites
|
|
The stuff (THF) is bad for your body.
|
|
|
garage chemist
chemical wizard
Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by Marvin
For the oxidation, if you follow the links from the page jimwig pointed to, you'll find a method using oxygen catalysed by copper oxide/silver
oxide under the heading 2-furoic acid, only a small amount of silver nitrate is needed and the yeild looks high. There is also a description of the
prep of furan from this.
|
Ok, thanks for this, now I know everything I need.
Sorry for not searching the site  I could have found that out myself.
When my thermometer + ground glass adapter finally arrive and I have enough time, I will try out the furfural synthesis (on a small scale, 20 ml 10%
H2SO4, 20g salt, 15g dried peanut shells- this should give 1,8 - 2,2 ml of furfural) . I'll report my results here.
I will use peanut shells instead of corn cobs first, only if this doesn't work I will get some corn cobs.
Does anyone know if empty corn cobs should be used or cobs with the kernels still in place?
@ Theoretic: THF is not very toxic, it's used in OTC solvent mixes. Furfural and especially furan are much more dangerous.
[Edited on 23-11-2004 by garage chemist]
|
|
|
solo
International Hazard
Posts: 3975
Registered: 9-12-2002
Location: Estados Unidos de La Republica Mexicana
Member Is Offline
Mood: ....getting old and drowning in a sea of knowledge
|
|
Ref: THF Synthesis
ONE-POT SYNTHESIS OF TETRAHYDROFURAN DERIVATIVES FROM ALLYLIC ALCOHOLS
AND VINYL ETHERS BY MEANS OF PALLADIUM(I1) ACETATE
Keigo Fugami , Koichiro OshimaX, and Kiitiro Utimoto
Tetrahedron Letters,Vol.28,No.7,pp 809-812,1987
Summary
Treatment of a mixture of allylic alcohol and vinyl ether in thepresence of Pd(OAc)2 provides 2-alkoxy-4-alkenyltetrahydrofuran in good yield.
[Edited on 24-11-2004 by solo]
Attachment: TL 1987,28,809.pdf (229kB)
This file has been downloaded 1338 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
|
|
|
mick
Hazard to Others
Posts: 338
Registered: 3-10-2003
Member Is Offline
Mood: No Mood
|
|
THF
THF is an good solvent for a lot of reactions.
Organometallic reactions work well in dry THF, more polar than ether so it dissolves more stuff. It is very good for organolithium reactions because
the lithium needs to be highly solvated under anhydrous conditions. With ether, under anhydrous conditions, most things are so insoluble because they
are not solvated that nothing much happens.
Another good thing about THF is that it is miscible with water but easily salted out.
THF will also soften most plastics (except PTFE, to date) over time.
mick
|
|
|
cyclonite4
Hazard to Others
Posts: 480
Registered: 16-11-2004
Location: is unknown
Member Is Offline
Mood: Amphoteric
|
|
THF in Pipe Glue
| Quote: | Originally posted by mick
THF will also soften most plastics...
mick |
Yeah, I think this is why it is used in PVC pipe glues, to soften the surface of the pipe to allow the adhesive to bond better.
@Polverone: Ive found glues with higher than 25% THF, infact i was just gluing pipes for a spudgun when i saw the back of the container (next to the
flammability warnings) saying "ADHESIVE contains Flammable Liquids
30-60% Tetrahydrofuran 30-60% Cyclohexanone"
This means a minimum of 30%, upto 60% (unlikely though) THF.
I can get this pipe glue in large amounts relatively cheap (for me anyway), all i need is a way of isolating the THF.
|
|
|
Darkfire
Hazard to Others
Posts: 292
Registered: 3-1-2003
Location: California
Member Is Offline
Mood: Wondering
|
|
Lo Voc has 50%-70% THF.
If its just resin, THF, and cylcohexanone distilation should work well.
[Edited on 14-12-2004 by Darkfire]
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
|
|
|
cyclonite4
Hazard to Others
Posts: 480
Registered: 16-11-2004
Location: is unknown
Member Is Offline
Mood: Amphoteric
|
|
I know i can distill the THF and cyclohexanone out of the resin, but how difficult will the seperation of the two be, i cant find any data in my books
here on boiling points.
Just a curious question: I left some pipe glue on a piece of pipe for a few minutes and then tried to scrape it off. A large piece of the PVC came off
and it was very soft. Is THF the one responsible for the softening of the pipe?
|
|
|
Darkfire
Hazard to Others
Posts: 292
Registered: 3-1-2003
Location: California
Member Is Offline
Mood: Wondering
|
|
This is what you do, i just tryed this 2 minutes before typing this so it works. Take the pipe cement and dump it in a beaker water with about 3/4 the
volume of the cement. Then take a stir rod and mix well, the resin with form a ball around ur stick, keep mixing until ur sure the water has disolved
all of the THF and the resin is no longer liquidy but a soilid ball. Now filter the resin from the mix, and squeze even drop out of the resin ball.
Dump in a bit more than enough salt to saturate the water and poof organic layer floats to the top, use a sep funnel or just a plastic bag to
seperate the two layers. Theres your THF and any other solvents in the can. Thats as far as i got. Now to get rid of the rest add this to some water
and add in some sulfite to kill the peroxides and get rid of the ketones and seperate again. Then you have your THF.
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
|
|
|
cyclonite4
Hazard to Others
Posts: 480
Registered: 16-11-2004
Location: is unknown
Member Is Offline
Mood: Amphoteric
|
|
Great!
Cyclohexanone is a ketone, so the sulfite should kill it. But by kill, what do you mean, what new compound(s) would form?
|
|
|
Darkfire
Hazard to Others
Posts: 292
Registered: 3-1-2003
Location: California
Member Is Offline
Mood: Wondering
|
|
I think it complexes to it and will sink into the water layer.
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
|
|
|
jimwig
Hazard to Others
Posts: 215
Registered: 17-5-2003
Location: the sunny south
Member Is Offline
Mood: No Mood
|
|
corn cops 'er cobs
i found corn cobs for about $12 / 50# online. try abrasive suppliers - industrial wholesale.
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
I undferstand that THF can be made by the acid hydrolysis, usually with dilute sulfuric acid, followed by distillation, of the particular type of
cellulose found in corn cobs. The initial product is furfural, C4H3OCHO, from which the -CHO is removed to produce furan, C4H4O, which is then
hydrogenated to THF, C4H8O.
Wood and sugar and some other carbohydrate materials can also be used.
|
|
|
Marvin
National Hazard
Posts: 995
Registered: 13-10-2002
Member Is Offline
Mood: No Mood
|
|
John, what do you think half the posts in this thread are about?
Wood cannot be used, ordinary sugars cannot be used.
jim,
What are the units to that price?
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
I am not sure exactly what they do, but I have seen a reference to wood and sugar being used to make furfural. The process would have to be somewhat
different from that using corn-cobs.
|
|
|
PainKilla
Hazard to Others
Posts: 306
Registered: 29-4-2004
Member Is Offline
Mood: No Mood
|
|
How interesting, xylitol is a direct derative of xylose, which is a precursor to furfural. Furfural is simply made by heating xylose under acidic
conditions. This can be converted to THF by further heating in presence of acid.
Would it be possible to somehow reduce xylitol into xylose? This would be quite an easy synthesis of THF, as xylitol is about 10$ per 5 pounds, and
this would make A LOT of THF... I am not sure however whether the strucutre of xylitol is actually a pentose ring or a straight structure. If it is a
ring, then someone could perhaps figure out a way towards THF synthesis?
|
|
|
frogfot
Hazard to Others
Posts: 212
Registered: 30-11-2002
Location: Sweden
Member Is Offline
Mood: happy
|
|
Is there an OTC source for pentoses? That acid catalysed preparation of furfural would probably work with any pentose, cyclic or not..
One would sure benifit from using starting material of higher sugar content..
Btw, I've always wondered, in OrgSyn page where they're using corn cobs, do they take cobs in dry weight?
|
|
|
Esplosivo
Hazard to Others
Posts: 491
Registered: 7-2-2004
Location: Mediterranean
Member Is Offline
Mood: Quantized
|
|
Yes frogfot, '... 1.5kg of dry corn cobs...'. Therefore I think they do intend the dry weight.
Surely where I live no pentoses are available OTC. I might buy them from a chem supplier buy they are quite expensive for small quantities (as small
as 25g of ribose). Hope this helps.
Edit: May I ask what's wrong with using xylitol, it is a pentose and is available OTC (used in diets since it contains a third less calories than
other sweetners if I remeber correctly). I don't think it would be too difficult to obtain. If a chem supplier is the only option I doubt many
questions will be asked regarding its use.
And btw, the cyclic and linear isomers of sugars, such as pentoses (eg xylitol) are in equilibrium with each other such that all will be present. In
solution the cyclic structure will predominate, I'm not sure in the solid state though. (The cyclic sugar may also possess isomers of the beta-
and alpha- type, but thats just an extra detail...)
[Edited on 9-2-2005 by Esplosivo]
Theory guides, experiment decides.
|
|
|
PainKilla
Hazard to Others
Posts: 306
Registered: 29-4-2004
Member Is Offline
Mood: No Mood
|
|
Was my post totally disregarded? I just mentioned that xylitol is cheap and easily avaialbe from many sources. Xylose is it's parent sugar and
the direct precursor to furfural which is easy to make into THF. I am a bit... um.. not clear of mind now so Ill finish this later.
|
|
|
frogfot
Hazard to Others
Posts: 212
Registered: 30-11-2002
Location: Sweden
Member Is Offline
Mood: happy
|
|
| Quote: |
'... 1.5kg of dry corn cobs...'. Therefore I think they do intend the dry weight.
|
Oh, damn sorry.. I have actually read the translated version of that text (in Russian) and they didn't mention this (maby this was concidered
obvious.. I dunno) ..so I never bothered to reread the original text..
PainKilla, that's useful info but I meant pentoses other than xylitol. I did a quick search on google and didn't find any local sources..
well maby I should search harder.. [rolleyes].. 
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
MAD SCIENCE!
Carbon Efficiency and the Surface Chemistry of the Actinides: Direct Formation of Furan from Acetylene over -UO3
Authors: Madhavaram H.; Idriss H.
Source: Journal of Catalysis, February 2002, vol. 206, no. 1, pp. 155-158(4)
Publisher: Academic Press
Abstract:
This work presents the direct oxidative coupling of two molecules of acetylene to furan (C4H4O) over the surface of pure polycrystalline -UO3. For
comparison, only traces of furan are formed over -U3O8 and none on UO2 surfaces. A comparison to the reactions of other C2 compounds (ethanol (H.
Madhavaram and H. Idriss, J. Catal. 184, 553 (1999)), acetaldehyde (H. Madhavaram and H. Idriss, Catal. Today 63, 309 (2000)), and ethylene (H.
Madhavaram and H. Idriss, J. Catal. 184, 553 (1999); H. Madhavaram and H. Idriss, Stud. Surf. Sci. Catal. 110, 265 (1997)) over -UO3 indicates the
presence of two routes for making furan from C2 compounds: one via aldolization and the other via oxidative coupling. © 2002 Elsevier Science (USA).
|
|
|
PainKilla
Hazard to Others
Posts: 306
Registered: 29-4-2004
Member Is Offline
Mood: No Mood
|
|
Some things that are pentoses includes:
Xylan
Xylose
Xylitol
Also something of interest is that xylan goes by the name hemicellulose. Pentosanes are also found in DNA, though we wont be using that method  . I have seen some stuff that says perhaps xylitol could be used, but they had no
references and I cant seem to find them anyway :p.
I will see if my health food store has it and see if this is indeed possible .
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
Xylitol is used as a substitute for ordinary sugar (sucrose) in some peppermints I have seen in supermarkets. It is used because it does not cause
dental decay; the decay-causing bacteria cannot metabolize it to carboxylic acids (like lactic acid).
With regard to dimerizing acetylene to furan over UO3, presumably made from depleted uranium (nearly pure U-238), and presumably with a source of
oxygen to give the formula C4H4O (if from the UO3 as a catalyst, it would have to be re-oxidized), does anyone knows of an outlet that sells UO3? I am
aware of uranyl (UO2++) salts being available as analytical reagents and for use in photochemistry.
[Edited on 10-2-2005 by JohnWW]
|
|
|
BromicAcid
International Hazard
Posts: 3253
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
Just something I've been thinking over, disregard this if I've posted it elsewhere on the forum. But what about making THF from diethylene
glycol?
The trick is of course getting the alcohol groups on the ends to somehow pop off and form a carbon-carbon bond between those ends. Much easier said
then done of course. The only method I've come up with (mind you I haven't covered this material in a while) is to react diethylene glycol
with phosphorus tribromide:
HOCH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>OH ----(PBr<sub>3</sub> -->
BrCH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>Br
And from that little product (haloethers are nasty!) dissolve in an inert solvent and drip into a suspension of sodium metal to do a Wurtz reaction to
give the THF.
BrCH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>Br + 2 Na ----->
(-CH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>-)
Something more realistic anyone?
|
|
|
| Pages:
1
2
3
4 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
