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                 Info on the reducing agent Red-Al, aka Vitride
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Strontium:

Information from not me.......

After a couple of reductions the last days I can truly say -Fuck the LAH, all
the way down to the sulfur pit it once came from. Red-Al IS really the easy way
to go reducing nitro-compounds with a metal hydride.

Red-Al comes as a ready to use liquid.
70:30 Red-Al:Toluene

Red-Al is non-pyrophoric

Reductions can in most cases take place without any dilution at all. Just add
the dry nitro-compound as it is, in small portions.
Example: 10g over 5 minutes, or less.

The litterature says that reflux should be maintained for about 2hrs after
addition is complete. If you are in a hurry and 50-60% yield is sufficient,
then skip the reflux. You have at least 50% yield direct after the addition is
complete.

No need for cooling during addition since 80-110 deg C is a perfect reaction
temp. Just add to compound to be reduced at a rate that keeps the toluene
boiling.

Workup is a beauty.

After the reaction is complete, hydrolyze with 5%(aq)NaOH, very carefully in the
beginning since unreacted Red-Al reacts violently with water. 175ml 5% NaOH/mol
Red-Al used. Add portionwise and stir well after every addition. When this
ration is used the aluminum salts will stay in solution as sodium aluminate. No
precipitation whatsoever. Just one organic phase and a water phase. Separate
them and wash the organic phase twice with water to dissolve the 2-methoxyethanol
formed during the hydrolysis. Now acidify the organic phase with 5-10%HCl and
separate. Eventual honey is now in the water layer. Make this water sloution
alkaline and the honey separates out as usual. Extract with DCM or toluene and
evaporate solvent under reduced pressure. Water aspirator works just fine for
boiling off toluene at 40-50 deg C.

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Slappy:

I can't find any literature that directly relates to reducing Nitro compounds
though. Or any organics for that matter. Anyway here's a little something to
chew on.

---

Sodium Aluminum Hydride Bis-(Methoxyethoxide), 70% in Toluene

You'll want to check this ref out first:
- Tetrahedron Lett., 3303, 1968.

More info can be found here, but mainly involve inorganic and organometallic reactions:

- J. Organomet. Chem., English; Vol. 355; (1988) 359 - 378; JORCAI;
- Inorg. Chem., English; Vol. 23; (1984) 2388 - 2390; INOCAJ;
- Organometallics, English; Vol. 6; (1987) 1829 - 1831; ORGND7;

It is also used as an intermediate for ion conducting network polymers:
- Check Chem. Mater. 3, 418, 1991.

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Strontium:

Red-Al, Vitride, Sodium dihydrobis(2-methoxyethoxy)aluminate, Sodium aluminum
bis(2-methoxyethoxy)hydride...... CAS [22722-98-1]

For reducing nitro-compounds one need to use 3 moles red-al to one mole
nitro-compound. Even if not needed it´s a good thing to use a small amount of
toluene to dilute the reaction if it should get too hot.

After a few trials and errors using Red-Al and obtaining crappy yields, some
adjustments have been done. To perform reductions of nitroethenes or propenes,
this is how to do:

1. Dissolve the nitroalkene to be reduced in toluene. The solubility is not that
   exeptional but OK.

2. Pour the amount Red-Al to be used in a reaction vessel. Dilute this with
   equal amount(by volume)toluene. For a reduction using 100ml diluted Red-Al
   use a 500ml reaction vessel.

3. Start adding the nitroalkene solution in 10-15 1-2ml portions/min. Keep
   adding in this manner until temp reached 50 deg C. Stop adding and let stir
   until temp dropped back to about 30 deg C. Due to good heat transfering
   properties of toluene, temp drops back in a matter of minutes.

4. When all nitroalkene has been added perform hydrolysis with 175ml
   5%(aq)NaOH/mol Red-Al(1 mol Red-Al=280ml). Do this dropwise until the first
   violent reaction has subsided. This is unreacted Red-Al being chewed away by
   the water. You´ll notice when this reaction is over. Then add NaOH soln in
   50ml portions. Separate the bottom water layer from the top toluene layer.
   Wash the toluene with two portions water to get rid of the produced
   2-methoxyethanol. 2-methoxyethanol is rather toxic so be careful with it.

You do now have a toluene solution of your freebase together with impurities.
Work this up in the usual way.

In my original posting on this topic I stated that the nitroalkene could be
added dry to the undiluted Red-Al. The violent reaction conditions will create a
mess of side ractions. When work up is done a huge amount of black tar will be
the major product. Dry adding can work for some more sturdy compounds but not
for most nitroalkenes. Therefore dilution is a nessicity.

THF can vey well be used as solvent for the nitroalkene instead of toluene. This
will not interfear with the reduction in any way.

If the reduction is done according to the above descriptions one can expect 50%
yield. If on the other hand reflux is being maintained for two hours after all
nitroalkene have been added, 70-80% yield can be expected.

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