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Author: Subject: THF ( tetrahydrofuran)
atombum
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[*] posted on 15-8-2004 at 14:40
THF ( tetrahydrofuran)


As tetrahydrofuran seems to be rapidly turning into a hard-to-find solvent, I became curious of who offered it and at what price. Every supplier had a bit of info on it that became one of those questions that bugs the hell out of you and yet you discover is almost impossible to find an answer to via search engines-
Why in the world is there a hazmat charge placed on every amount of it? Flammability? No, ether (even isopropyl!!), and probably any similiar bp alkanes, can be sent under limited qty. exemption. Toxicity? That's a no brainer. Peroxidation? Well again consider the ethers, plus THF is usually inhibited.
Does anyone know why this would be done?

[Edited on 23-11-2004 by chemoleo]
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JohnWW
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[*] posted on 15-8-2004 at 15:19


Tetrahydrofuran, cyclo-(CH2)4O, a cyclic ether (like furan, furfural, pyran, oxetane, dioxane), obtained by hydrogenation of furan (obtained by reduction of furfural, itself obtained by the acidic dehydration and hydrolysis of cellulose containing materials like bran), is supposed to be a common solvent in industrial and laboratory synthetic organic chemistry, e.g. for organolithium and organomagnesium compounds. It is also used, in its adduct product with BH3 by reaction with B2H6, to obtain organoboron compounds

It has a m.pt. of -108ºC and a b.pt. of 65.4ºC, which makes it useful for hosting very low-temperature reactions.

It is also slightly more volatile than the lowest non-cyclic ethers. There does not seem to be any particular chemical reason why it should be regarded as more hazardous than these other light ethers like diethyl ether. Perhaps the answer is that it is a good solvent for the production of certain illegal drugs or explosives.

John W.
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[*] posted on 15-8-2004 at 15:40


From comparing the MSDS's of THF and Diethyl Ether, I've found one difference... THF will form hazardous polymers while Diethyl Ether will not. I don't know if that warrants the Hazmat charges though.

I don't think the charges are related to its illegal uses though; it would make more sense to scrutinize the buyer more heavily than to simply make him pay a little extra.




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[*] posted on 15-8-2004 at 16:12
THF


IIRC, TetraHydroFuran is a substance used in the manufacture of
many synthetic drugs. LSD comes to mind. I can't say for sure, but this
1 is probably on the DEA's watched list. If it is, BE CAREFUL if you order it !




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[*] posted on 15-8-2004 at 20:14


In response to MadHatter- Like an increasing number of compounds, it's probably on the high-priority end of that list.
And in regards to what Samosa stated, I agree that the illicit material manufacture aspect of the chemical is probably not relevent to transit. The more heavily(or at least similarly) watched, and more flammable diethyl ether is not hazmat.
I also tend to agree that it may very well be the polymerization aspect that was mentioned. The MSDSs do tend to indicate a greater instability than aliphatic ethers. And, this would probably be aggrevated to a more severe degree when uninhibited.
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[*] posted on 15-8-2004 at 20:36


JohnWW, furan obtained by the reduction of furfural? Interesting, whence goes the offending carbon?

Wild guess but cyclic ether of 4 carbon atoms to me suggests people are making GHB from it.
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[*] posted on 15-8-2004 at 20:45


Thats an intresting idea THF to GBL is a known synth, but that still shouldnt affect the price of shipping.



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[*] posted on 15-8-2004 at 21:23


GBL to GHB is a pretty trivial process, so for me that clinches it, it probably is being abused that way and this may well be why its getting hard to find.

Hazmat charges may be at the discression of the supplier, I didnt find much in the way of enforced classification. On the other hand the following from 'Hazmat magazine" might tip the balence somewhat.

"Carcinogenicity -- The International Agency for Research on Cancer (IARC) has not evaluated THF for its carcinogenic potential. Inhalation studies in rats have produced inconsistent results, in that liver and/or kidney tumours were observed in some studies but not in others. However, clear evidence of carcinogenicity has been observed in inhalation studies with mice."

Its ether like, fairly low toxicity and carcinogenic.
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[*] posted on 15-8-2004 at 21:48


Quote:
Originally posted by Marvin
GBL to GHB is a pretty trivial process, so for me that clinches it, it probably is being abused that way and this may well be why its getting hard to find.

Hazmat charges may be at the discression of the supplier,


All shipping charges are at the discretion of the supplier.

With anyand every precursor in demand, there will be those who will stop selling it to the public out of morality or concern about liability in this litigous world, and there will be those that seek to profit from the distribution of it, they are called opportunists.

"Hazmat fees", Handling charges....packaging fees...are just another way of adding to the cost of a substance, in a roundabout way, so that you won't notice the real price until the checkout line.

Sort of like the way some companies give 100% MONEY BACK GUARANTEE!!! TRY FOR THIRTY DAYS WITH ABSOLUTELY NO RISK!!! and then charge you a 30% "restocking fee" if you do send it back.

I think most of us have had the experience of getting suckered into a "great buy" on ebay or LabX only to discover the ridiculous S+H fees that boost the product to near normal market values.....those bastards!....they killed my naivete!




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[*] posted on 15-8-2004 at 21:54


Just off the top of my head, I think furan, cyclo-(CH)4O, which has aromatic resonance structures involving a positive charge on the O, can be obtained from furfural, C4H3O-CHO, by heating with red phosphorus, which removes the -CHO (which is on the 1-carbon). Furfural is obtained by heating cellulose substances with H2SO4, the concentration of which has to be carefully controlled to avoid dehydration to carbon. However, surprisingly few organic chemistry textbooks seem to have anything about the preparation of furan or furfural, or the removal of -CHO groups from aldehydes.

John W.
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Marvin
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[*] posted on 16-8-2004 at 00:43


I went over furfural reasonably well (I thought) in a thread on roguesci. Its not the cellulose thats important, its hemicellulose which breaks down into sugars that are largly pentoses and those are what dehydrate into furfural. Bran is good, corncobs are good, I have some methods from mid 19th century but the one on orgsyn from 1940's or so is better.

The only methods I know of making furan from furfural though are the brute force industrial method, decarbonylation with palladium/carbon, and the obvious method of oxidise to the acid and decarboxylate. This turns out to be fairly easy by just heating the acid to boiling point (Organic synthesis). Orgsyn also mentions in passing furfural + sodalime, or fused sodium/potassium hydroxide, I wonder if this includes oxidation or is just canizzaro based. Nothing about Red P or removal by reduction.

I dont see how heating with Red P would work, as it is the carbon has to come off as monoxide, any reduction would leave the carbon in a lower oxidation state! Do you have a reference for this method?

Democritus, there is a big difference between the supplier enforcing hazmat packaging and the goverment. I have noticed a lot of places enforcing hazmat on items only when shipping within the US. This seems to be to keep to legal requirements.
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[*] posted on 16-8-2004 at 04:12


I have actually been hunting for this solvent for a while. Does anyone know of an OTC source for THF. I don't need much, around 250 mL should do.
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[*] posted on 16-8-2004 at 10:03


It's a significant component of various PVC glues and primers, but always mixed with a variety of other chemicals; methyl ethyl ketone and cyclohexanone were most common from the few MSDS sheets I glanced at, sometimes acetone too. You'd be lucky to find a formulation with more than 25% THF in it. I don't know of any way to isolate it in high purity, but that could be a starting point if you wanted to come up with a method yourself.



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[*] posted on 20-8-2004 at 11:28


I see 50,000 gallon rail cars filled with THF all the time, going west usually. Some friends of mine who live on a farm close to railroad tracks have gotten some items from there when a train stops occasionnaly, like a pallat of toilet paper, etc. If you could find the drain on one of those tankers, you could fill up an auxillary fuel tank in the back of a pickup rather fast with it. :o:D


Bah, Im rambleing again.




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JohnWW
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[*] posted on 20-8-2004 at 13:11


You see a lot of THF on rail tanker cars "going west"? (literally as well as figuratively). Perhaps you could make some inquiries as to the destination where those tanker cars are unloaded, and approach the recipient to obtain a small quantity.

John W.
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[*] posted on 21-8-2004 at 05:19


Does anyone know whether THF is conductive? If it's not, its very low MP might just make it suitable to use as a replacement for expensive Fluorinert for use as a coolant fluid in experimental computer overclocking together with liquid N2... but perhaps I'm dreaming.

And it might just dissolve the PCB components...




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JohnWW
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[*] posted on 21-8-2004 at 13:19


The only problem with such a proposed use of THF as a coolant, in place of a fluorocarbon, is its inflammability. Its flash point in air mixtures would not be very high.

JOhnW.
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[*] posted on 27-8-2004 at 13:19


It's also an excellent solvent, particularly for PVC.
What are the wires insulated with?
(flash point is about 20 below zero)

BTW THF is not more volatile than the lowest ethers; dimethyl ether is a gas.
(Edit; just checked, methoxy ethane (Bpt 7C) is too.)

[Edited on 27-8-2004 by unionised]
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[*] posted on 31-8-2004 at 09:53


Is THF really a substance which is used to make a lot of drugs?GBL comes to my mind,but I can´t think of more substances. I hope it is allowed to talk about the drugs,which require THF as a starting material,because no instructions for the synthesis are said.But now I´m interesed.I knew that it can be used for GBL,but the synthesis is shit,if the wrong catalyst is used.I tried it three times,but the reaction got out of control and a brown liquid was spilled all over my garage and my lab,because it begun suddenly to boil very vigorous.Because of this I think it would be better to obtain GBL fron someone who has access,for example it is used as an industrial solvent and some people sell it here in Germany.
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[*] posted on 31-8-2004 at 10:31


You want the HIVE. I think we can discuss stuff as long as it is theoretical, and not practical. As far as the DEA is concerned, as long as the chemical is used in any stage of the production of any common drug, it will be put on one of the lists of watched substances. HCl,H<sub>2</sub>SO<sub>4</sub> KMnO<sub>4</sub>, you name it.
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[*] posted on 31-8-2004 at 11:19


The emphasis on theoretical-not-practical is reserved for energetic materials. Anyone can ask any question here that they please; the trick to not be told "look elsewhere" is to phrase the question in a suitably high-minded way.

Example of the wrong way:
"How do I make meth?"

Example of the right way:
"What is the simplest way to prepare benzyl cyanide starting from toluene?"

The second question is far more specific, shows that the poster has already done some homework and now wants help with specifics rather than generalities, and is a perfectly acceptable home-chemistry challenge regardless of how the benzyl cyanide will be used once produced.

Some questions on substances of a "controversial" nature might be best-asked elsewhere, but will never be driven away from this site if asked in an appropriate manner. This is a site for chemistry more so than cookbook-recipes.




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[*] posted on 30-9-2004 at 10:22


THF is available in drums from about half of the general industrial chemical supply houses. Liondell is the main manufacturer and they probably have a hundred distributors in the US. Drum prices are usually 1.00 to 2.00/#.
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[*] posted on 30-9-2004 at 13:27


I think we're looking for a source that isn't going to make the DEA pay us a little visit.
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[*] posted on 22-11-2004 at 14:26


Now I also got interested in furane chemistry and I want to learn more and prepare furfural from hemicellulose.
I heard that peanut shells can be used as a starting material, so I'm going to use that.
They are first boiled with 5% H2SO4 at a pressure of 4 bar (can be done in a kitchen pressure cooker), this converts the pentosanes into pentoses (sugars with 5 C- atoms). These are then somehow converted into furfural, probably by heating with stronger H2SO4. Seems like a lengthy process.
Döbereiner first made furfural by distillation of "Kleie" (don't know the english word for it, it's just another hemicellulose containing material, I'm going to use peanut shells) with dilute H2SO4, so the pressure cooking seems to be unnecessary.
The most important question: What is the required concentration of the H2SO4, and how much peanut shells should be used per 100ml of H2SO4?

When I have the furfural, I also want to make furan. The decarboxylation of 2-furanecarbonic acid seems to be the easiest way. Any ideas on how to oxidise the furfural to 2-furanecarbonic acid?

These syntheses all seem very interesting- making something as exotic as furfural and furane and maybe even THF from organic waste material. Furane chemistry is going to be one of my new projects.

[Edited on 22-11-2004 by garage chemist]
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[*] posted on 22-11-2004 at 18:16


FURFURAL-


http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0280
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