Author Topic: aluminum ethoxide  (Read 1529 times)

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PEYOTE

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aluminum ethoxide
« on: September 27, 2001, 05:45:00 AM »
Can I use (EtO)3Al instead of EtONa like strong base? Not for a particular rxn, but in general. It can be easily made OTC.

cilliersb

  • Guest
Re: aluminum ethoxide
« Reply #1 on: September 28, 2001, 06:47:00 AM »
I've been pondering the same thing for quite long now, but I thing that EtOK is more of a possibility.

Would you happen to have any literature on the (Eto)3Al synth?

obituary

  • Guest
Re: aluminum ethoxide
« Reply #2 on: September 28, 2001, 03:28:00 PM »
try using Mg alkoxides instead- easier to make and has been discussed here already
 check some of Osmium's (?) posts here a short while back

PEYOTE

  • Guest
Aluminum tert-butoxide synthesis
« Reply #3 on: September 30, 2001, 08:30:00 AM »

Antoncho

  • Guest
Re: aluminum ethoxide
« Reply #4 on: September 30, 2001, 09:13:00 AM »
:)  this article contains a link at Al(EtO)3 preparation, here it is:


In a flask fitted with a reflux condenser is placed 27 parts of aluminum filings or groats. This is treated with 276 parts of absolute alcohol, 0.1 to 0.25 part of mercuric chloride, and several crystals of iodine. After a few minutes a violent evolution of hydrogen takes place, and by heating on the water bath for several hours the ethoxide is produced in the form of a grayish powder.
Unchanged alcohol is removed by distillation from an oil bath until the residual material melts to a dark-colored liquid. It is then poured into a Claisen flask and distilled under reduced pressure, using a short air condenser and a Pyrex suction flask as a receiver. Since aluminum ethoxide tends to sublime, a glass-wool filter is inserted between the receiving flask and the vacuum line to prevent clogging. A free flame is necessary, and distillation should be rapid. While the distillate is still liquid it is poured into a Pyrex flask and allowed to cool. It forms a tough, white mass which must be preserved in a well-stoppered flask to prevent adsorption of water vapor. A yield of 90 per cent of the theoretical amount may be obtained.
For the present reaction, where a trace of water does no harm, some of the ethoxide may be fused and poured into a mortar and covered with a watch glass until cool, when it can be powdered and weighed.
The submitter has found that it is possible to make a large quantity of the ethoxide by the above method with 95 per cent alcohol, but that success is more certain if the alcohol is refluxed and distilled twice over quicklime.


Another thing is that Al(EtO)3 is very different in nature from alkali and alkali earth metals' alkoxides. The bond btween Al and AlkO is covalent (strong), while in case of the above metals it's ionic (weak) - that's why the former is insoluble in alcohols. I think, Al alkoxides can't bee used as bases, or for -Br to -MeO exchange - although i might bee wrong here.

Antoncho