found this in festers book
The preferred procedure is to react one mole of benzaldehyde with two moles of N
methylalanine in
DMSO solvent. Let's take a small scale example using 30 ml of benzaldehyde. It would
react with 60
grams ofN-methylalanine to give roughly 25 to 30 grams of a mixture of
ephedrine and
pseudoephedrine
hydrochloride.
Now place 250 ml of DMSO into a suitable heating vessel such as a round bottom flask
with reflux
condenser ... or a lava lamp if you are ghetto ... add a magnetic stir bar. .. and 60 gr of N
methyl alanine.
Then add 10 ml of the 30 ml of the benzaldehyde. It is best to add it in portions to save on
the total
amount of DMSO solvent used. This makes the clean up at the end of the reaction much
more practical.
Heat this mixture to about 130 C if one is using piperonal, but benzaldehyde will react at a
lower
temperature. Look for the fizzing of C02 as your visual clue, and go with the lower
temperature. Let it
fizz for an hour or so, then add the next 10 ml portion of the 30 ml total benzaldehyde add.
Let it
similarly fizz for an hour before adding the last 10 ml portion of benzaldehyde.
After the last addition of benzaldehyde, let the mixture heat at the lowest fizzing
temperature, and then
tum up the heat slowly. The max with benzaldehyde should be at about 130 C. Piperonal
would react
much more easily, but allow the mixture to fizz to complete reation. Take no more than 6
hours on this
stage of the reaction. Just push up the heat to get it going.
Now for the new part of the reaction Uust discovered), "Vinegar", yes the really cheap
distilled white
vinegar at the grocery store, greatly increases yield by breaking up a dimer complex the
product forms.
At this scale, add 500 to 600 ml of that cheap grocery store vinegar, and swirl to mix it in.
Then add from
50 to 100 ml of toluene or xylene. This solvent serves as a catcher for the BS we don't want.
You will note that after adding the two volumes of vinegar, the toluene or xylene now form a
layer on
top of the DMSO and product layer. This is important as it is the crap catcher. The mixture
now must be
heated to reflux boiling temperature for 3 to 6 hours to break up the dimer and give the
greater yields one
wants.
Heat the mixture to boiling gently for three to six hours. Then let it cool. This has broken up
the dimer.
Add about a shot glass of hardware store hydrochloric acid to the mixture and mix it in. This
will assure
that all the
ephedrine stays out of the toluene layer.
Now put the reaction into a sep funnel and shake it. Let this settle and the toluene layer on
top would
have crap and unreacted benzaldehye in it. Put it aside for further work, the water layer
underneath has
the product.
Next base the DMSO and water solution containing the
ephedrine and pseudoephedrine.
Add a
solution of lye to it with sirring and shaking until the pH is 13 plus. This should not take all
that much lye
to reach that level. Then add about 100 ml of toluene or xylene to extrtact the product.
Save it. Extract
again with 50 ml of toluene or xylene.
Wash the combined extracts with some water to rid them of DMSO, then let then sit to
shed water and
then transfer to a dry beaker minus the water droplets, and bubble with dry HCL to give
about 30 grams
of pure pseudoephedrine and
ephedrine mixture as hydrochloride crystals. Keep water out
of the dry HCI
bubbling mixture!
