Easy Oxidation of THF to GBL

[Rhodium]

To a stirred mixture of 7.2g (0.1 mol) tetrahydrofuran (0.1 mol) in 100ml water there was added 15.1g of sodium bromate and 13.6g (0.1 mol) potassium hydrogen sulfate. External cooling was necessary to keep the temperature of the solution between 25-30°C. Stirring was continued for 16 hours at room temperaturem, after which time all the THF had been consumed. To quench any excess bromine formed, acidic sodium sulfite solution was used [bisulfite should work just as good]. Thus 140-150ml of a 10% solution was added and 13.6g (0.1 mol) potassium hydrogen sulfate. The reaction was cooled and extracted with 5x30ml dichloromethane. The combined organic layers was dried over MgSO4 and the solvent removed under vacuum. The residue was distilled to give gamma-butyrolactone in 73% yield (bp 204-205°C).

The procedure is extensively optimized, and most part of the article deals with the mechanism and kinetics of this particular reaction.

Reference: Tetrahedron 56, 1905-1910 (2000)

[Prdy2GO]

Yes! I like I like it a lot quite intreging I must say.
Do you think that it can be scaled up say 10 or even a 100 times with all the same values?
Don't look at me I didn't do it!

[Rhodium]

I believe it is perfectly scalable, the only thing you should watch out for is possible overheating of the reaction mixture just after the bromate is added (perhaps slow addition is a good idea at larger scales). The authors reccommend to use a reflux condenser to avoid loss of THF if the cooling is not strong enough. Try the reaction out at this scale, and report back to us how much heat is evolved.

I would also say be careful to not skip the bromine neutralization step with sulfite. It is not good if you carry bromine over into your product. Potassium hydrogen sulfate is easily made by yourself by mixing equimolar amounts of KOH and H2SO4 in a water solution, and evaporating the water. Sulfite/bisulfite is OTC.

[foxy2]

Hmmm wonder if Sodium Iodate would work also??
Do Your Part To Win The War

[Osmium]

Well, from an economic standpoint it might be more interesting if chlorate will work. Or if that reaction can be made catalytic in bromate. chlorate/H+, H2O2/H+ or oxone maybe? Sounds like it might work.

I once did some analytical chemistry on phenols and phenolethers, and I remember that I used iodate which is a strong enough oxidiser to destroy the aromatic ring of methoxybenzenes and convert the CH3O into formaldehyde.

[Rhodium]

According to the article I took the synthesis from, the actual oxidizing agent is bromine. The role of bromate is just to re-oxidize bromide to bromine again.

[Osmium]

Bromine??!  

Well of course, that makes sense!

5 Br(-) + BrO3(-) + a couple of H(+) -----> 3 Br2 + 3 H2O !!

Somehow bromate oxidises something and gets reduced to bromide. This bromide reacts with the bromate synproportionating into Br2, which will do the the oxidising business from now on. In every catalytic cycle more Br2 is produced, that's why they use so much Na2SO3 in the end! I was wondering why that was necessary. Makes sense now!

Well, if that's the mechanism then it will be possible to make this procedure a catalytic one, and to run with NaBr/H2O2 instead! Or NaBr/oxone! Or NaBr/persulfate!

Hoooray!

Damn damn damn! I already see the headlines of the  newspapers:
"Banned date rape drug use on the rise again ; hits streets with a vengeance. How to protect YOUR CHILD! Read more on page 3..."

[terbium]

"Banned date rape drug use on the rise again ; hits streets with a vengeance. How to protect YOUR CHILD! Read more on page 3..."
Funny that you mention that. There was a full page article in the Nov. 26 Los Angeles Times titled In The Grip Of GHB.

Some quotes from the article:

"This is the most addictive drug I've ever seen," says Dr. Stephen W. Smith ... "People are desperate to get off of it because it's destroying their lives," he says ...

Patti Trovato-Ragano of Naples Fla., believes that her son ... might still be alive if he had received proper care for his GHB addiction.

Former LAPD Det. Trinka Porratta says statistics underestimate the problem.

and so on ad nauseum. If it bleeds, it leads.

Well, now that the "crack baby" epidemic has been debunked, it looks like the people who make their living fighting drugs are looking for a new demon.

[Prdy2GO]

Thanks Rhodium.
Swim was thinking she could try it as written first and she said she will let me know how it goes. Just so happens she has all the components Prdy2go so no need to make the potassium hydrogen sulfate. One question did come up about acidic sodium sulfide is this the same as sodium sulfide reagent? Or perhaps Na bi or metabisulfate is just as good? thanks
TTFN
Don't look at me I didn't do it!

[Rhodium]

NOT sodium sulfide (Na2S)!

The reagent they are using is sodium sulfite (Na2SO3) which they acidify, to get a solution of H2SO3 (essentially an aqueous solution of SO2). Using sodium hydrosulfite (aka bisulfite aka metabisulfite) will also give the same H2SO3 upon acidification.

[Osmium]

Well, in the end it doesn't really matter, all these sulfides/sulfites will reduce the Br2.

[Prdy2GO]

Rhodium,
Where can the reference be found online? or perhaps you could post it kind sir?

Don't look at me I didn't do it!

[Rhodium]

I will post a PDF of the article soon, as soon as my favorite reference-gatherer downloads it from his Tetrahedron Online account.

http://tetonline.com/

[Prdy2GO]

Thank you
And yes SUIFITE of course that is what I wah thinking but not typeing. Sorry for the typos that may apper in this on as it is dark in here.
SWIM at the keys now.
Started the reaction early today about 58F in the lab looking over the glassware and due to size needed decided to scale up a bit ease of finding the results is what was on the minde at the time. I am going to list this out as the steps taken. I was not privy to the reference so I may have done this all wrong this may be an example of how not to do this.
Expecting a exothermic reaction72g of THF were placed in a 2l FB beaker and 1l DH2O precooled this in the fridge placed on the stirrer was a stainless steal lab bucket the beaker placed inside and several packets of blue ice and water 3" egg stirrbar set on #6 (cornning 10x10 620) began adding the powered sodium bromide a little at a time noted temp at 15C no real change in temp so I dumped it all in (151g.) Began the addition of the potassium hydrogen sulfate much the same way the temp began to drop to 9c then as low as 4c. after ab hour I removed the cooling setup took the temp probe out and checked to make sure it was working correctly. It checked out ok slowly came up to RT and is still spinning set on 9 now. It has been 5 hrs and the grinding of the stirrbar have long gone looks thicker and is sn opalesent in apperence.
Any one care to coment on the steps taken does this sound right still wondering why is was indothermic?
Don't look at me I didn't do it!

[Rhodium]

Are you still making typing errors, or did you use Sodium Bromide (NaBr) instead of the required Sodium Bromate (NaBrO3) in the reaction?

[Chemikaze]

Hahahaha way to go:)
Cool
Everybody in the house with a half an ounce
Not weed I meant coke dumb ass sit down!

[Prdy2GO]

Nope I used sodium bromide oops. Guess I start over? LOL ithink it's kinda of funny see what I mean about the dark it is hard to read in this cave.
Don't look at me I didn't do it!

[Rhodium]

Yup, you need to start over. Better luck next time!

[Osmium]

No!
Do not start over. Drip in some H2O2. Or add some oxone or peroxodisulfate. Or calcium hypochloride. Prove me right.

[foxy2]

Electrochemical synthesis of g-butyrolactone from tetrahydrofuran.    
Kirsanova, A. I.; Smirnova, M. G.
Elektrokhimiya  (1978),  14(4),  627. Journal  written in Russian.   
Abstract
A method is described for the anodic oxidn. of tetrahydrofuran (THF)  [109-99-9] to g-butyrolactone  [96-48-0] in a KBr soln. with Na2SO4 as a supporting electrolyte on a Pt electrode at pH .apprx. 1.  The anodic efficiency reaches 98% when a diaphragm is used.  THF is oxidized indirectly by BrO3- formed during the oxidn. of Br-.  At higher pH (6-7) the oxidizing agent is BrO- formed at the anode and the current efficiency decreases due to the simultaneous formation of oxybutyric acid.
Do Your Part To Win The War