WW4000 (Stranger)
05-25-03 00:16
No 435253
      Use of THF instead of Two phase system  Bookmark   

When nitrating propenyl benzenes with sodium nitrite and sulphuric acid, most literature calls for two phase system of water phase and ether phase.

Now, who thinks all reagents (ie: NaNO2 H2SO4 propenylbenzene) would be happy to react together in the solvent tetrahydrofuran ?

Also, what alternatives are there in this instance to ether? What about DCM?

Will post more later, please comment
 
 
 
 
    Rhodium
(Chief Bee)
05-25-03 01:31
No 435269
      Solvents for pseudonitrosite synthesis  Bookmark   

Did you UTFSE first, or even think before posting?

There is a point in making the nitrosation of propenylbenzenes in a two-phase solution, and that is that the relatively acid-sensitive alkene (in the ether phase) won't have to be in contact with the acid more than necessary, and that only the N2O3 gas formed in the aqueous layer will bubble through the ether and react with the alkene to form the pseudonitrosite.

Using THF, the alkene will be in contact with acid during the whole reaction, and it will probably not appreciate that. I also don't believe sodium nitrite is at all soluble in THF.

DCM is not a substitute for ether either, as it is heavier than water, and won't let any formed N2O3 gas bubble through it. If you UTFSE, you'll see that people have tried to use petroleum ether instead of diethyl ether, and while it worked, it produced inferior results. If you read my Pseudonitrosite FAQ (../rhodium/chemistry /pseudonitrosite.html), you'll see that Toennies' method to synthesize pseudonitrosites was to add a NaNO2 solution to a solution of the propenylbenzene in glacial acetic acid, but that method also produced lower yields.
 
 
 
 
    Antibody2
(Hive Addict)
05-26-03 02:19
No 435507
      asarone in HOAc resulted in a purple ...  Bookmark   

asarone in HOAc resulted in a purple polymerized ball of crap
 
 
 
 
    WW4000
(Stranger)
05-26-03 15:18
No 435606
      ok  Bookmark   

Many thanks Rhodium for explaining how and why the two phase system is used. I should have UTFSE. Off to check out the diethyl ether synth on your website then.... cheers WW4000