Author Topic: aromatic ethers thru decompn of diazonium salts?  (Read 1192 times)

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phenethyl_man

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aromatic ethers thru decompn of diazonium salts?
« on: August 12, 2004, 11:35:00 AM »
Does anyone have a write up on a procedure for the synthesis of aromatic ethers through decomposition of their diazonium salts?  For ex. phenyldiazonium chloride -> anisole, via heating/decomposing the salt in MeOH..  Is this even possible?


lugh

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No Write Ups Seem To Bee Available
« Reply #1 on: August 14, 2004, 06:20:00 PM »
No write ups seem to bee available except for possibly OS V 245 & 1099, but this is a time tested procedure in the literature, albeit with side reactions that reduce the yield by forming the aldehyde or hydrocarbon  :P  It's best to keep the diazo compound wet, as when dry these compounds have a bad habit of detonating  :(  See Amer Chem Jour 15 379 (1893) in which anisole sulphonic acid is prepared by warming the diazonium salt, diazobenzene sulphonic acid and methanol under thirty atmospheres of pressure  ;)  Other references that may bee helpful are Philos Trans 164 583 (1864),  Ber 3 98 (1870) and Amer Jour Pharm 107 242 (1935)  8)


phenethyl_man

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Appreciate the references..
« Reply #2 on: August 17, 2004, 11:23:00 AM »
Appreciate the references.. I find it strange the seemingly complete lack of literature on this reaction despite it's potential utility.  Of course the alternative is to just decompose in water and then alkylate the phenol.  However, this condenses the process down to one reaction and eliminates the need for toxic/hard to aquire (in my case) methylating agents.

In the following ref:

THE ACTION OF ETHYL ALCOHOL ON PARATOLUIDINE DIAZONIUM HYDROCHLORIDE AND OF SULFURIC ACID ON THE ETHYL ETHER OF PARACRESOL.
Percival Rudolph Roberts, Gellert Alleman;
J. Am. Chem. Soc.; 1911; 33(3); 391-396.


..they prepare p-ethoxytoluene from p-toluidine by boiling the diazo compound in ethyl alcohol.  However this passage from the article doesn't make this procedure seem all that attractive:

"Frequently the decomposition had to be checked by pouring cold water on the balloon flask, or the whole solution would be lost through the condenser tube. Several fires resulted from the ignition of the alcohol, which was shot out of the condenser tube on certain occasions, and others from the alcohol scattered in consequence of flasks broken from sudden shock during the too rapid decomposition of the diazo compound. Fires were subsequently prevented by extinguishing all the flames in the room in which the decomposition was effected as soon as it was well under way. The decomposition was completed in about twenty minutes."

They do make a reference to Alleman, Am. Chem. J., 31, 24 (1904), where they seem to imply that the preparation of methyl ethers is much more easily achieved; exemplified by the action of methanol on paratoluidine sulfate.  I've been unable to find this reference, however, and of course, seeing as I value my place of residence, I am hesitant to do some novel research of my own in this area ;)  Nonetheless, seeing as prepn. of methyl ethers is all I'm really interested in, this is most interesting..

Isolation of the dry pyrophoric diazo compound would not really be necessary; the compound could be diazotised in methanol/conc. sulfuric acid followed by subsequent decomposition by *carefully* warming the mixture.

If anyone can find any more literature on this it would be much appreciated.


lugh

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Experimental Details
« Reply #3 on: August 17, 2004, 07:35:00 PM »
Here's the article you mentioned, Am. Chem. J., 31, 24 (1904)



These pages from Sidgwick's Organic Chemistry of Nitrogen and Perkin's Organic Chemistry should provide the experimental details you require; but it's quite possible that this reaction is absolutely useless for what you contemplate, since the methyl group has been known to dissociate during the reaction  ;)





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