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All 14 posts   Subject: Me3SiCl alcohol deoxygenation method work?   Please login to post   Down

 
    abc123
(Stranger)
07-28-01 01:01
No 199423
      Me3SiCl alcohol deoxygenation method work?     

I have been searching the old hive files to see if the
 Me3SiCl + CH3CN + NaI method from TS2 reduces ephed (in heptane)...or does this method not work?

I couldn't find the answer

anyone know if the method does work?
 
 
 
 
    Rhodium
(Chief Bee)
07-28-01 01:09
No 199425
User Picture 
      Re: Me3SiCl method work?     

Everything speaks for that it should, it has just not been tested by any of the bees yet. Do you want to make this wonderful discovery yourself and be the first one to tell us?

https://www.rhodium.ws
 
 
 
 
    abc123
(Stranger)
07-28-01 05:30
No 199474
      Post deleted by Rhodium     

 
 
 
 
    Rhodium
(Chief Bee)
07-28-01 16:23
No 199553
User Picture 
      Re: Me3SiCl method work?     

The most common form of petroleum ether consist mainly of heptane (with some pentane, hexane etc.). I'm looking forward to hear of yuor results. Try to stick to the published procedure as much as possible with no shortcuts whatsoever to make sure that in case of failure, it is not because of any unnecessarily introduced variables, making your testing of the method as credibly as possible. A failure by someone who doesn't even have a scale does not establish that the method isn't useful for ephedrine. Also make sure that your ephedrine is absolutely pure and doses not contain any other things, such as binders from ephed pills. 

On what scale are you planning to perform the synthesis, and how do you plan to isolate and purify the product (as that is not included in the TSII writeup)? I would suggest that you scale the procedure by 5-10x the amounts in TSII. What kind of lab and analysis equipment do you have access to?

Do you have access to the original article (Tet Lett 28, 3817 (1987) I think) or just the experimental part from TSII? I would be interested in the exact reaction mechanism.
 
 
 
 
    abc123
(Stranger)
07-28-01 23:14
No 199618
      Re: Me3SiCl method work?     

10X scale is going to be tried (1st)

to isolate the product, DCM will be used because the acetonitrile, KI, and Me3SiCl will go in the aqueous phase.
Then comes an acid base extraction. I could then take (forget the chem's name) and seperate out the un-reduced ephed to find % yeild. Think that will work? 

I dont have any analytical equiptment but I could sneak an IR and possibly an NMR..will take some time though. I will know if what I want was made or not

I know it is possible to seperate ephed from meth.  is it also possible to easily seperate iodo-ephed beacuse these are the only three nitrogen containg cmpds I am aware of with any appreciable concentration
 
If the method doesnt work the first time I will keep trying untill I get it to work because if it is possible to reduce 1-phenylethanol then it is very very likely that ephed should also but there may be some changes needed and only research will find the changes needed

and I dont have the original article but I may have it soon and if I do I will send it
 
 
 
 
    Rhodium
(Chief Bee)
07-28-01 23:51
No 199622
User Picture 
      Re: Me3SiCl method work?     

You seem to have access to university resources, so I suggest that you for simplicity's sake first just try to run a TLC on your product, together with ephedrine and an authentic sample of methamphetamine, then you can see if any of your desired product was to be found in your product.

Oh, I like it so much when somebody with real equipment tries out a new method! smile

https://www.rhodium.ws
 
 
 
 
    abc123
(Stranger)
08-10-01 18:27
No 203189
      Re: Me3SiCl method work?     

I am working at my legal lab and I have a question. The Me3SiCl is making the mixture acidic (pH3) and the salt of the amine was used....not the freebase. There is some precip at bottom that isnt dissolving. Anyone think that allitle NaOH should be used to make the mixture neutral?

abc123
 
 
 
 
    Rhodium
(Chief Bee)
08-10-01 18:31
No 203193
User Picture 
      Re: Me3SiCl method work?     

Perhaps a little triethylamine would be better to use (or perhaps pyridine). I don't know if the Me3SiCl is stable if it comes into contact with NaOH. Could the precipitate be NaI - I don't believe it would be soluble in pet ether.
 
 
 
 
    abc123
(Newbee)
08-10-01 19:11
No 203213
      Post deleted by Rhodium     

 
 
 
 
    abc123
(Newbee)
08-12-01 18:39
No 203780
      Re: Me3SiCl method work?     

The method does work but I believe the product may not be fully reacted. I never really did meth before but I have done adderal and dex spans...the product made seems to be about half as strong as what I believe it should be ...but the method defiently worked.

I added all reactants and let spin for 24 hours..it took about 12 hours for everything to dissolve..I was then left with a blackish tar at the bottom of the pet ether. After 24hours I added conc NaOH solution untill the pH went from 3 to 12+. The black tar completely dissapeared when water was added. In the sep funnel there was a yellow meth layer on top of a water layer. The yellow organic layer was then extracted and was added to a 10% HCL solution to make a pH of less than 5. The acidic water layer turned slightly yellow. there was then a second hcl extraction. the pooled extracts were then evaporated on a pryex plate and steam bath (this was done because I was on an hour lunch break and I wanted it done quick)..after all water evaporated I was left with a yellow salt that was easily cleaned with acetone

This method definetly worked but needs more research..maybe a longer reducing time..because there wasnt an amine in the research article

it possibly could be fully reacted..I havent done anything except try it..calamus will try it soon..he would probaly know better than me
 
 
 
 
    Rhodium
(Chief Bee)
08-12-01 18:55
No 203784
User Picture 
      Re: Me3SiCl method work?     

What is the TLC verdict of the reaction (comparing the result with ephedrine)? What was the yield of the cleaned product?
 
 
 
 
    abc123
(Newbee)
08-12-01 21:07
No 203820
      Re: Me3SiCl method work?     

thats what i was trying to explain..i dont have any TLC papers on hand..I only analyzed it via swallowing...I am doing another rxn but i will let it go for 2 days instead of 1

i will analyze both some time this upcoming week

all I know for know is that some was reduced (%=?) and I will see calamus today and will get his opinion..

I will post what I find

any suggestions are welcomed

anyone have a guess on the mech?
ephedrine + KI ==> iodoephedrine + Me3SiCl ==> Me3Si-ephedrine + CH3CN ==> amine ??????
 
 
 
 
    abc123
(Newbee)
08-19-01 19:41
No 205880
      Re: Me3SiCl method work?     

dreaming about this rxn from TS2 (following that exact  procedure)..I would have to give it a very bad rating..probaly a 1.5 out of 10. if I had to guess I would say that the product was anywhere from 5 to 15 % reacted. increasing the rxn time from 1 day to 1 and a half did slightly give a stronger product. 1-phenylethanol doesnt have an amine group. the amine group may cause resonance stabilization. I believe it is possible to fully reduce the hydroxyl but more vigourous conditions are probaly needed..maybe some sodium-borohydride or LAH could help but I read that Me3SiCl plus NaBH4 or LAH reduce something like a COOH to ROH but not any further (at least what I read.) I will keep dreaming untill it gets reduced.....any suggestions are appreciated

abc123
 
 
 
 
    Rhodium
(Chief Bee)
05-16-04 01:04
No 507401
User Picture 
      Me3SiCl-NaI-MeCN: Benzylic Alcohol Deoxygenation
(Rated as: excellent)
    

Me3SiCl-NaI-CH3CN as an Efficient and Practical Reducing Agent for Benzylic Alcohols
Takashi Sakai, Kazuyoshi Miyara, Masanori Utake, and Akira Takeda
Tetrahedron Letters 28(33), 3817-3818 (1987) (https://www.rhodium.ws/pdf/deoxygenation.tmscl-nai-mecn.pdf)

Abstract
Secondary and tertiary benzylic alcohols are reduced conveniently to the corresponding aryl alkanes by using Me3SiCl-NaI-CH3CN reagent in hexane.

A typical procedure for the present reduction is as follows:

To a mixture of Me3SiCl (1.54 ml, 12 mmol), Nal (1.8 g, 12 mmol), and acetonitrile (0.5 ml, 12 mmol), was added a solution of 1-phenylethanol (244 mg, 2 mmol) in hexane (2 ml). The mixture was stirred for 24 h at room temperature. Dilution with water, extraction with ether and subsequent isolation process gave ethylbenzene (158 mg) with sufficient purity in 75% yield.


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